[ { "id": "authors:dkpkd-37987", "collection": "authors", "collection_id": "dkpkd-37987", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220708-324478200", "type": "book_section", "title": "Functional photoacoustic tomography of the human brain", "author": [ { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "orcid": "0000-0002-9212-6211", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "abstract": "This Conference Presentation, \"Functional photoacoustic tomography of the human brain,\" was recorded at SPIE Photonics West held in San Francisco, California, United States.", "doi": "10.1117/12.2631529", "publisher": "Society of Photo-Optical Instrumentation Engineers", "publication_date": "2022-06-02" }, { "id": "authors:q68dr-tmq22", "collection": "authors", "collection_id": "q68dr-tmq22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220307-189711000", "type": "book_section", "title": "Integration of photoacoustic computed tomography with multitargeted polymer-based nanoparticles visualizes breast cancer intratumor heterogeneity", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Patil", "given_name": "Deepanjali", "clpid": "Patil-Deepanjali" }, { "family_name": "Petruncio", "given_name": "Greg", "orcid": "0000-0002-2527-1064", "clpid": "Petruncio-Greg" }, { "family_name": "Paige", "given_name": "Mikell", "clpid": "Paige-Mikell" }, { "family_name": "Salvador-Morales", "given_name": "Carolina", "orcid": "0000-0002-2588-6608", "clpid": "Salvador-Morales-Carolina" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "orcid": "0000-0002-9212-6211", "clpid": "Oraevsky-Alexander-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "abstract": "One of the primary challenges in breast cancer diagnosis and treatment is intratumor heterogeneity (ITH), i.e., the coexistence of different genetically and epigenetically distinct malignant cells within the same tumor. Identification of ITH is critical for designing better treatments and hence to increase patient survival rates. Here, we report a non-invasive approach that integrates photoacoustic computed tomography (PACT) with multitargeted and multiplexed patchy polymeric photoacoustic contrast agents (MTMPPPCAs). The target specificity of MTMPPPCAs to distinguish estrogen and progesterone receptor-positive in breast tumors was demonstrated through both fluorescence and photoacoustic measurements and validated by tissue pathology analysis.", "doi": "10.1117/12.2610584", "publisher": "Society of Photo-optical Instrumentation Engineers", "publication_date": "2022-03-03" }, { "id": "authors:wep0g-h5x27", "collection": "authors", "collection_id": "wep0g-h5x27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220307-189707000", "type": "book_section", "title": "Multiscale photoacoustic tomography of a genetically encoded near-infrared FRET biosensor", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Verkhusha", "given_name": "Vladislav V.", "orcid": "0000-0002-2083-8121", "clpid": "Verkhusha-Vladislav-V" }, { "family_name": "Shcherbakova", "given_name": "Daria M.", "orcid": "0000-0003-3384-6363", "clpid": "Shcherbakova-Daria-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "orcid": "0000-0002-9212-6211", "clpid": "Oraevsky-Alexander-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography with genetically encoded near-infrared probes enables visualization of specific cell populations in vivo at high resolution in deep tissues. Here, we report a near-infrared Forster resonance energy transfer biosensor based on a pair of the near-infrared fluorescent proteins, miRFP670-iRFP720, which enables dynamic photoacoustic imaging of active biological processes. Specifically, we detected apoptosis in single cells at a resolution of ~3 \u00b5m in a mouse ear and mouse brain tumors (>3 mm in depth) at a spatial resolution of ~150 \u00b5m. These results open the way for high-resolution photoacoustic imaging of dynamic biological processes in deep tissues.", "doi": "10.1117/12.2610587", "publisher": "Society of Photo-optical Instrumentation Engineers", "publication_date": "2022-03-03" }, { "id": "authors:46y6t-fwq96", "collection": "authors", "collection_id": "46y6t-fwq96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200220-132155264", "type": "book_section", "title": "In vivo super-resolution photoacoustic computed tomography by localization of single dyed droplets", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2020", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhang", "given_name": "Pengfei", "orcid": "0000-0002-4226-1394", "clpid": "Zhang-Pengfei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The spatial resolution of photoacoustic (PA) computed tomography (PACT) is limited by acoustic diffraction. Here, we report in vivo superresolution PACT, which breaks the acoustic diffraction limit by localizing the centers of single dyed droplets. The dyed droplets generate much stronger PA signals than blood and can flow smoothly in blood vessels; thus, they are excellent tracers for localization-based superresolution imaging. The flowing droplets were first localized, and then their center positions were used to construct a superresolution image that exhibits sharper features and more finely resolved vascular details. A 6-fold improvement in spatial resolution has been realized in vivo.", "doi": "10.1117/12.2547562", "isbn": "9781510632431", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "publication_date": "2020-02-17", "pages": "Art. No. 112402U" }, { "id": "authors:0x02h-n5047", "collection": "authors", "collection_id": "0x02h-n5047", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200220-134102759", "type": "book_section", "title": "Photoacoustic computed tomography guided microrobots for targeted navigation in intestines in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2020", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Wu", "given_name": "Zhiguang", "clpid": "Wu-Zhiguang" }, { "family_name": "Yang", "given_name": "Yiran", "orcid": "0000-0001-8770-8746", "clpid": "Yang-Yiran" }, { "family_name": "Hu", "given_name": "Peng", "orcid": "0000-0002-2933-1239", "clpid": "Hu-Peng" }, { "family_name": "Gao", "given_name": "Wei", "orcid": "0000-0002-8503-4562", "clpid": "Gao-Wei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Tremendous progress in synthetic micro/nanomotors has been made for potential biomedical applications. However, existing micro/nanomotor platforms are inefficient for deep tissue imaging and motion control in vivo. Here, we present a photoacoustic computed tomography (PACT) guided investigation of micromotors in intestines in vivo. The micromotors enveloped in microcapsules exhibit efficient propulsion in various biofluids once released. PACT has visualized the migration of micromotor capsules toward the targeted regions in real time in vivo. The integration of the developed microrobotic system and PACT enables deep imaging and precise control of the micromotors in vivo.", "doi": "10.1117/12.2547559", "isbn": "9781510632431", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "publication_date": "2020-02-17", "pages": "Art. No. 112402R" }, { "id": "authors:xmxf4-78688", "collection": "authors", "collection_id": "xmxf4-78688", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-151143100", "type": "book_section", "title": "International Photoacoustic Standardisation Consortium (IPASC): overview (Conference Presentation)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Bohndiek", "given_name": "Sarah", "clpid": "Bohndiek-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The International Photoacoustic Standardisation Consortium (IPASC) emerged from SPIE 2018, established to drive consensus on photoacoustic system testing. As photoacoustic imaging (PAI) matures from research laboratories into clinical trials, it is essential to establish best-practice guidelines for photoacoustic image acquisition, analysis and reporting, and a standardised approach for technical system validation. The primary goal of the IPASC is to create widely accepted phantoms for testing preclinical and clinical PAI systems. To achieve this, the IPASC has formed five working groups (WGs). The first and second WGs have defined optical and acoustic properties, suitable materials, and configurations of photoacoustic image quality phantoms. These phantoms consist of a bulk material embedded with targets to enable quantitative assessment of image quality characteristics including resolution and sensitivity across depth. The third WG has recorded details such as illumination and detection configurations of PAI instruments available within the consortium, leading to proposals for system-specific phantom geometries. This PAI system inventory was also used by WG4 in identifying approaches to data collection and sharing. Finally, WG5 investigated means for phantom fabrication, material characterisation and PAI of phantoms. Following a pilot multi-centre phantom imaging study within the consortium, the IPASC settled on an internationally agreed set of standardised recommendations and imaging procedures. This leads to advances in: (1) quantitative comparison of PAI data acquired with different data acquisition and analysis methods; (2) provision of a publicly available reference data set for testing new algorithms; and (3) technical validation of new and existing PAI devices across multiple centres.", "doi": "10.1117/12.2506044", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-03-04", "pages": "Art. No. 108781N" }, { "id": "authors:abj1j-wst80", "collection": "authors", "collection_id": "abj1j-wst80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-150016451", "type": "book_section", "title": "Multifocal photoacoustic microscopy through an ergodic relay (Conference Presentation)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Li", "given_name": "Yang", "orcid": "0000-0002-4939-8174", "clpid": "Li-Yang" }, { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Hsu", "given_name": "Hsun-Chia", "clpid": "Hsu-Hsun-Chia" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To date, most optical-resolution photoacoustic microscopy (OR-PAM) systems rely on mechanical scanning with confocally aligned optical excitation and ultrasonic detection. As a result, the imaging speed of these systems is limited by the scanning speed. Although several multifocal OR-PA computed tomography (MFOR-PACT) systems had been developed to address this limitation, they were hindered by the complex design in a constrained physical space. Here, we present a two-dimensional (2D) MFOR-PAM system based on a 2D microlens array and an acoustic ergodic relay. This system is able to detect PA signals generated from 400 optical foci in parallel with a single-element transducer, and then raster scan the optical foci patterns to form an image. This system has improved the imaging resolution of a conventional photoacoustic ergodic relay system from 220 \u03bcm to 13 \u03bcm. Moreover, this system has reduced the imaging time of a conventional OR-PAM system at the same resolution and laser repetition rate by 400 times. We demonstrated the ability of the system with both in vitro and in vivo experiments.", "doi": "10.1117/12.2513502", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-03-04", "pages": "Art. No. 108781C" }, { "id": "authors:ns4mb-7b458", "collection": "authors", "collection_id": "ns4mb-7b458", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-143835667", "type": "book_section", "title": "High-resolution high-contrast mid-infrared imaging of fresh biological samples with ultraviolet-localized photoacoustic microscopy (Conference Presentation)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "He", "given_name": "Yun", "clpid": "He-Yun" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Hwang", "given_name": "Jeeseong", "clpid": "Hwang-Jeeseong" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Label-free mid-infrared (MIR) imaging provides rich chemical and structural information of biological tissues without staining. Conventionally, the long MIR wavelength severely limits the lateral resolution owing to optical diffraction; moreover, the strong MIR absorption of water ubiquitous in fresh biological samples results in high background and low contrast. Here, we present a novel approach, called ultraviolet-localized MIR photoacoustic microscopy (ULM-PAM), to achieve high-resolution and water-background\u2013free MIR imaging of fresh biological samples. In our approach, a pulsed MIR laser thermally excites the sample at the focal spot, and a pulsed ultraviolet (UV) laser photoacoustically detects the resulting transient temperature rise owing to the Gr\u00fcneisen relaxation effect, thereby reporting the intensity of the MIR absorption by the sample. The imaging resolution of our method is determined by the wavelength of the UV laser, which is one order of magnitude shorter than that of the mid-IR laser (2.5 \u03bcm to 12 \u03bcm). In addition, in the UV region from 200 nm to 230 nm, most important organic molecules in biological tissues, including proteins, lipids and nuclei acids, have strong absorption, while water is transparent. Therefore, our method can achieve high resolution and water-background free IR imaging of fresh biological samples. For cell cultures, our method achieved high-resolution and high-contrast infrared imaging of lipids, proteins. The capability of label-free histology of this method is also demonstrated in thick biological tissues, such as brain slices. Our approach provides convenient high-resolution and high-contrast MIR imaging, which can benefit diagnosis of fresh biological samples.", "doi": "10.1117/12.2515616", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-03-04", "pages": "Art. No. 1087825" }, { "id": "authors:c575c-0cd87", "collection": "authors", "collection_id": "c575c-0cd87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-150606290", "type": "book_section", "title": "Dual-wavelength high-speed functional photoacoustic microscopy of mouse brain with a Raman laser at 1-MHz A-line rate (Conference Presentation)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "He", "given_name": "Yun", "clpid": "He-Yun" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Label-free functional photoacoustic microscopy (fPAM) has become a popular technology in small-animal hemodynamic studies. Here we report a stimulated-Raman-scattering-based (SRS) dual-wavelength high-speed fPAM that has achieved volumetric imaging at a 1 MHz A-line rate with capillary-level resolution. Potassium gadolinium tungstate (KGd(WO4)2) crystal is used as a Raman shifter to convert the pump 532 nm picosecond-pulsed laser to the first order Stokes line at 558 nm through the SRS effect with ~40% efficiency and a much narrower line width compared with previous fiber-based SRS PAMs. We also developed a water-immersible micro-electro-mechanical system scanner for scanning a ~4-mm range at a 500 Hz B-scan rate, while maintaining the optic-acoustic confocal alignment. This scanner is assembled entirely from commercially available components, facilitating replication. The detection sensitivity of our fPAM is also improved by employing a high numerical aperture polyvinylidene fluoride ultrasonic transducer, whose acoustic impedance matches better with tissue coupling medium than traditional ceramic transducers. The high sensitivity combined with ~2.4 \u00b5m resolution enabled our fPAM to image single red blood cells with a signal-to-noise ratio of ~27 dB. Compared with our previous laser-pulse-width based fPAM, we achieved simultaneous imaging of hemoglobin concentration and oxygenation with a 5-fold increase in imaging speed. Moreover, our system works in a convenient free-space manner compared to previous SRS-based PAMs. We applied it to imaging vasculature and blood oxygen saturation on mouse brains in both resting and stimulated states.", "doi": "10.1117/12.2510658", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-03-04", "pages": "Art. No. 1087824" }, { "id": "authors:b2rwr-r6906", "collection": "authors", "collection_id": "b2rwr-r6906", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-152902324", "type": "book_section", "title": "Exponential path of photoacoustic tomography to the largest conference at Photonics West: omniscale imaging from organelles to organisms (Conference Presentation)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography has been developed for in vivo functional, metabolic, molecular, and histologic imaging by physically combining optical and ultrasonic waves. Broad applications include early-cancer detection and brain imaging. High-resolution optical imaging\u2014such as confocal microscopy, two-photon microscopy, and optical coherence tomography\u2014is limited to superficial imaging within the optical diffusion limit (~1 mm in the skin) of the surface of scattering tissue. By synergistically combining light and sound, photoacoustic tomography conquers the optical diffusion limit and provides deep penetration at high ultrasonic resolution and high optical contrast. Photoacoustic tomography has two major embodiments: photoacoustic computed tomography and photoacoustic microscopy. In photoacoustic computed tomography, a pulsed broad laser beam illuminates the biological tissue to generate a small but rapid temperature rise, which leads to emission of ultrasonic waves due to thermoelastic expansion. The unscattered pulsed ultrasonic waves are then detected by ultrasonic transducers. High-resolution tomographic images of optical contrast are then formed through image reconstruction. In photoacoustic microscopy, a pulsed laser beam is delivered into the biological tissue to generate ultrasonic waves, which are then detected with a focused ultrasonic transducer to form a depth resolved 1D image. Raster scanning yields 3D high-resolution tomographic images. Super-depths beyond the optical diffusion limit have been reached with high spatial resolution. The annual conference on PAT has grown exponentially since early 2000 and become the largest in SPIE's 20,000-attendee Photonics West since 2010.", "doi": "10.1117/12.2515432", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-03-04", "pages": "Art. No. 108780W" }, { "id": "authors:xwv4f-c4k96", "collection": "authors", "collection_id": "xwv4f-c4k96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190408-105837786", "type": "book_section", "title": "In vivo photoacoustic multi-contrast imaging and detection of protein interactions using a small near-infrared photochromic protein", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Shemetov", "given_name": "Anton A.", "clpid": "Shemetov-A-A" }, { "family_name": "Hu", "given_name": "Peng", "orcid": "0000-0002-2933-1239", "clpid": "Hu-Peng" }, { "family_name": "Shcherbakova", "given_name": "Daria M.", "clpid": "Shcherbakova-D-M" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Verkhusha", "given_name": "Vladislav V.", "orcid": "0000-0002-2083-8121", "clpid": "Verkhusha-V-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic (PA) computed tomography (PACT) is a non-invasive imaging technique offering optical contrast, high resolution, and deep penetration in biological tissues. PACT, highly sensitive to optical absorption by molecules, is inherently suited for molecular imaging using optically absorbing probes. Genetically encoded probes with photochromic behavior dramatically increase detection sensitivity and specificity of PACT through photoswitching and differential imaging. Starting with a DrBphP bacterial phytochrome, we have engineered a near-infrared photochromic probe, DrBphP-PCM, which is superior to the full-length RpBphP1 phytochrome previously used in differential PACT. DrBphP-PCM has a smaller size, better folding, and higher photoswitching contrast. We have also developed an advanced PACT technique, which combines the reversibly-switchable photochromic probes with single-impulse panoramic PACT, termed RS-SIP-PACT. Using RS-SIP-PACT, we have characterized DrBphP-PCM both in vitro and in vivo as an advanced near-infrared photochromic probe for PACT. We introduce two phytochromes into the same mammalian cells, resulting in a distinctive decay characteristic in comparison with the cells expressing DrBphP-PCM only. By discriminating the different decay characteristics, we successfully separate multiple cell types in deep tissues. The simple structural organization of DrBphP-PCM allows engineering a bimolecular PA complementation reporter, a split version of DrBphP-PCM, termed DrSplit. DrSplit enables PA detection of protein-protein interactions in deepseated mouse tumors and livers, achieving 125-\u03bcm spatial resolution and 530-cell sensitivity in vivo. The combination of RS-SIP-PACT with DrBphP-PCM and DrSplit holds great potential for non-invasive multi-contrast deep-tissue functional imaging.", "doi": "10.1117/12.2509198", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-02-27", "pages": "Art. No. 1087818" }, { "id": "authors:darpf-32s21", "collection": "authors", "collection_id": "darpf-32s21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190404-110929115", "type": "book_section", "title": "Quantitative cell nuclear imaging by dual-view optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2019", "author": [ { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Cai", "given_name": "De", "clpid": "Cai-De" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Chen", "given_name": "Sung-Liang", "orcid": "0000-0002-0572-5110", "clpid": "Chen-Sung-Liang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "An estimated ~250,000 new cases of both invasive and non-invasive breast cancer were diagnosed in US women almost every year. To reduce the local recurrence rate, the breast conserving surgery (BCS) is widely used as the initial therapy, which is to excise the tumor with a rim of normal surrounding tissue such that no cancer cells remain at the cut margin, Patients with positive margin commonly require a second surgical procedure to obtain clear margins. To this end, optical-resolution photoacoustic microscopy (OR-PAM) with ultraviolet (UV) laser illumination (OR-UV-PAM) has been developed for providing label-free, high-resolution, and histology like imaging of fixed, unprocessed breast tissue. To further improve the performance of OR-UV-PAM, here, we introduce dual-view UV-PAM (DV-UV-PAM) to significantly improve the axial resolution, achieving three-dimensional (3D) resolution isotropy. We first use 0.5 \u03bcm polystyrene beads and carbon fibers to validate the resolution isotropy improvement. Imaging of mouse brain slices further demonstrates the improved resolution isotropy, revealing the 3D structure of cell nuclei in detail, which facilitates quantitative cell nuclear analysis.", "doi": "10.1117/12.2509219", "isbn": "9781510623989", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2019-02-27", "pages": "Art. No. 108780R" }, { "id": "authors:sem46-es964", "collection": "authors", "collection_id": "sem46-es964", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-144425867", "type": "book_section", "title": "Clinical photoacoustic computed tomography of the human breast in vivo within a single breath hold", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Lin", "given_name": "Li", "orcid": "0000-0002-0517-8436", "clpid": "Lin-Li" }, { "family_name": "Hu", "given_name": "Peng", "orcid": "0000-0002-2933-1239", "clpid": "Hu-Peng" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Appleton", "given_name": "Catherine M.", "clpid": "Appleton-C-M" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have developed a single-breath-hold photoacoustic computed tomography (SBH-PACT) system to detect tumors and reveal detailed angiographic information about human breasts. SBH-PACT provides high spatial and temporal resolutions with a deep in vivo penetration depth of over 4 cm. A volumetric breast image can be acquired by scanning the breast within a single breath hold (~15 sec). We imaged a healthy female volunteer and seven breast cancer patients. SBH-PACT clearly identified all tumors by revealing higher blood vessel densities and lower compliance associated with the tumors.", "doi": "10.1117/12.2290987", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-03-21", "pages": "Art. No. 104942X" }, { "id": "authors:6vtth-5mf13", "collection": "authors", "collection_id": "6vtth-5mf13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104552807", "type": "book_section", "title": "Imaging dichroism by photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Shen", "given_name": "Yuecheng", "orcid": "0000-0003-1990-8142", "clpid": "Shen-Yuecheng" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Qu", "given_name": "Yuan", "clpid": "Qu-Yuan" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Conventional photoacoustic computed tomography (PACT) images the spatial distribution of optical absorption, which is approximated as an isotropic optical property. The optical absorption of many biological tissues, however, is anisotropic. This anisotropy, known as dichroism or diattenuation, encodes rich information about molecular conformation and structural alignment. Here we report a novel imaging method called dichroism-sensitive PACT (DS-PACT). Using a lock-detection strategy, our method can measure the amplitude of tissue's dichroism and the orientation of the optic axis of uniaxial dichroic tissue, even at a depth of 3.25 transport mean free paths. We experimentally demonstrated DS-PACT by imaging plastic polarizers and ex vivo bovine tendons deep inside scattering media. Our method extends the functionality of PACT to include a new capability, imaging tissue absorption anisotropy.", "doi": "10.1117/12.2287432", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-03-15", "pages": "Art. No. 104941U" }, { "id": "authors:p9heb-qzj23", "collection": "authors", "collection_id": "p9heb-qzj23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104552942", "type": "book_section", "title": "Parameterized joint reconstruction of the initial pressure and sound speed distributions in photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Matthews", "given_name": "Thomas Paul", "clpid": "Matthews-T-P" }, { "family_name": "Poudel", "given_name": "Joemini", "clpid": "Poudel-J" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Accurate estimation of the initial pressure distribution in photoacoustic computed tomography (PACT) requires some knowledge of the sound speed distribution. However, the sound speed distribution is typically unknown. Further, the initial pressure and sound speed distributions cannot both, in general, be stably recovered from PACT measurements alone. In this work, a joint reconstruction method for the initial pressure distribution and a low-dimensional parameterized model of the sound speed distribution is proposed. By employing a priori information about the structure of the sound speed distribution, both the initial pressure and sound speed can be accurately recovered. The joint reconstruction problem is solved by use of a proximal optimization method that allows constraints and non-smooth regularization functions for initial pressure distribution. The gradients of the cost function with respect to the initial pressure and sound speed distributions are calculated by use of an adjoint state method that has the same per-iteration computational cost as calculating the gradient with respect to the initial pressure distribution alone. This approach is quantitatively evaluated through 2D computer-simulation studies for a small animal imaging model. The impact of the choice of the parameterized sound speed model is investigated. Even when the assumed parameterized sound speed model is inconsistent with the true sound speed distribution, the estimated initial pressure distribution is more accurate than that obtained by assuming a constant sound speed. The utility of the proposed approach is also demonstrated through application to experimental in vivo measurements of a mouse.", "doi": "10.1117/12.2291014", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-03-15", "pages": "Art. No. 104942V" }, { "id": "authors:qqv8t-3gy24", "collection": "authors", "collection_id": "qqv8t-3gy24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104553035", "type": "book_section", "title": "Label-free hypoxia measurement in a xenograft multiple myeloma model using optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Azab", "given_name": "Abdel K.", "orcid": "0000-0002-6371-2780", "clpid": "Azab-A-K" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Imai", "given_name": "Toru", "orcid": "0000-0002-9497-8549", "clpid": "Imai-Toru" }, { "family_name": "Muz", "given_name": "Barbara", "orcid": "0000-0003-4125-4624", "clpid": "Muz-B" }, { "family_name": "Yeh", "given_name": "Cheng-Hung", "clpid": "Yeh-Cheng-Hung" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In cancer research, regions of increasingly lowered oxygenation in tissue (hypoxia), which are due to tumor development, are considered to play an important role in activating various signaling pathways that facilitate further development of the cancer. However, devising a minimally invasive method to monitor tissue oxygenation has remained a challenge. Photoacoustic microscopy has been posed as a solution in a variety of preclinical research studies. Here, using optical-resolution photoacoustic microscopy (OR-PAM), for the first time, we non-invasively measured oxygenation and vascularization in vivo caused by multiple myeloma (MM) progression. Mice injected with MM cells tagged with green fluorescent protein were monitored with a fluorescence microscope for tumor progression over the course of 28 days. OR-PAM evaluated the oxygen saturation (sO2) and the blood vessel density in the cerebral bone marrow, where MM cells home. At 28 days after the injection of MM cells, the total sO2 had dropped by 50% in the developing tumor regions, while in the non-tumor developing regions it had dropped by 20% compared with the value at one day after MM injection. The blood vessel density had dropped by 35% in the tumor developing regions, while in the non-tumor developing regions it had dropped by 8% compared with the value at one day after MM injection. In summary, non-invasive measurement by OR-PAM correlated the development of hypoxia with to MM progression. It revealed decreased vascularization surrounding the tumor areas, which we feel can be ascribed to the rapid tumor progression.", "doi": "10.1117/12.2291782", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-03-15", "pages": "Art. No. 104942P" }, { "id": "authors:b3rt8-f1r02", "collection": "authors", "collection_id": "b3rt8-f1r02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104553589", "type": "book_section", "title": "Joint reconstruction of initial pressure distribution and acoustic skull parameters in transcranial photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Poudel", "given_name": "Joemini", "clpid": "Poudel-J" }, { "family_name": "Matthews", "given_name": "Thomas P.", "clpid": "Matthews-T-P" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The development of photoacoustic computed tomography (PACT) for neuroimaging in humans will fill an important void left by available imaging techniques. However, due to the presence of the skull, accurate image reconstruction in transcranial PACT remains challenging. Variations in the shear and longitudinal wave speed distributions due to the skull can induce strong aberrations in the measured photoacoustic wavefields. To mitigate these artifacts, image reconstruction methods in transcranial PACT require knowledge of these acoustic properties. However, such information may be difficult to obtain in practice. To circumvent this, we developed a joint reconstruction (JR) method for transcranial PACT where the longitudinal and shear speed distributions are reconstructed concurrently with the sought-after initial pressure distribution. The joint estimation of the initial pressure, longitudinal speed, and shear speed distributions from PACT data alone is unstable. To overcome this instability, we propose to incorporate prior information about the acoustic properties of the skull. Specifically, a low-dimensional parameterized acoustic representation of the skull is established with the aid of adjunct CT data. The use of a low-dimensional representation of the acoustic skull parameters effectively overcomes the instability of the JR problem and allows stable reconstruction of the acoustic skull parameters and the initial pressure distribution concurrently. To validate the proposed method, we conducted 3D numerical studies based on realistic human skull models derived from adjunct CT data. The efficacy of the proposed JR method was demonstrated through accurate reconstruction of the initial pressure, longitudinal speed, and shear speed distributions from PACT measurement data alone.", "doi": "10.1117/12.2290890", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-03-14", "pages": "Art. No. 104942U" }, { "id": "authors:438f3-gxf78", "collection": "authors", "collection_id": "438f3-gxf78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-155148719", "type": "book_section", "title": "Whole-organ atlas imaged by label-free high-resolution photoacoustic microscopy assisted by a microtome", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Hsu", "given_name": "Hsun-Chia", "clpid": "Hsu-Hsun-Chia" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In biomedical imaging, all optical techniques face a fundamental trade-off between spatial resolution and tissue penetration. Therefore, obtaining an organelle-level resolution image of a whole organ has remained a challenging and yet appealing scientific pursuit. Over the past decade, optical microscopy assisted by mechanical sectioning or chemical clearing of tissue has been demonstrated as a powerful technique to overcome this dilemma, one of particular use in imaging the neural network. However, this type of techniques needs lengthy special preparation of the tissue specimen, which hinders broad application in life sciences. Here, we propose a new label-free three-dimensional imaging technique, named microtomy-assisted photoacoustic microscopy (mPAM), for potentially imaging all biomolecules with 100% endogenous natural staining in whole organs with high fidelity. We demonstrate the first label-free mPAM, using UV light for label-free histology-like imaging, in whole organs (e.g., mouse brains), most of them formalin-fixed and paraffin- or agarose-embedded for minimal morphological deformation. Furthermore, mPAM with dual wavelength illuminations is also employed to image a mouse brain slice, demonstrating the potential for imaging of multiple biomolecules without staining. With visible light illumination, mPAM also shows its deep tissue imaging capability, which enables less slicing and hence reduces sectioning artifacts. mPAM could potentially provide a new insight for understanding complex biological organs.", "doi": "10.1117/12.2291056", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-02-19", "pages": "Art. No. 104942N" }, { "id": "authors:fzb3j-w0f38", "collection": "authors", "collection_id": "fzb3j-w0f38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-075329068", "type": "book_section", "title": "Photoacoustic microscopy enables multilayered histological imaging of human breast cancer without staining", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Aft", "given_name": "Rebecca L.", "clpid": "Aft-R-L" }, { "family_name": "Novack", "given_name": "Deborah V.", "clpid": "Novack-D-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In 2016, an estimated ~250,000 new cases of invasive and non-invasive breast cancer were diagnosed in US women. About 60\u201375% of these cases were treated with breast conserving surgery (BCS) as the initial therapy. To reduce the local recurrence rate, the goal of BCS is to excise the tumor with a rim of normal surrounding tissue, so that no cancer cells remain at the cut margin, while preserving as much normal breast tissue as possible. Therefore, patients with remaining cancer cells at the cut margin commonly require a second surgical procedure to obtain clear margins. Different approaches have been used to decrease the positive margin rate to avoid re-excision. However, these techniques are variously ineffective in reducing the re-operative rate, difficult to master by surgeons, or time-consuming for large specimens. Thus, 20-60% of patients undergoing BCS still require second surgeries due to positive surgical margins. The ideal tool for margin assessment would provide the same information as histological analysis, without the need for processing specimens. To achieve this goal, we have developed and refined label-free photoacoustic microscopy (PAM) for breast specimens. Exploiting the intrinsic optical contrast of tissue, ultraviolet (UV) laser illumination can highlight cell nuclei, thus providing the same contrast as hematoxylin labeling used in conventional histology and measuring features related to the histological landscape without the need for labels. We demonstrate that our UV-PAM system can provide label-free, high-resolution, and histology-like imaging of fixed, unprocessed breast tissue.", "doi": "10.1117/12.2291008", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-02-19", "pages": "Art. No. 1049443" }, { "id": "authors:q7z0k-zg347", "collection": "authors", "collection_id": "q7z0k-zg347", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-160453358", "type": "book_section", "title": "Linear-array based full-view high-resolution photoacoustic computed tomography of whole mouse brain functions in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2018", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhang", "given_name": "Pengfei", "orcid": "0000-0002-4226-1394", "clpid": "Zhang-Pengfei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) is a non-invasive imaging technique offering high contrast, high resolution, and deep penetration in biological tissues. We report a photoacoustic computed tomography (PACT) system equipped with a high frequency linear array for anatomical and functional imaging of the mouse whole brain. The linear array was rotationally scanned in the coronal plane to achieve the full-view coverage. We investigated spontaneous neural activities in the deep brain by monitoring the hemodynamics and observed strong interhemispherical correlations between contralateral regions, both in the cortical layer and in the deep regions.", "doi": "10.1117/12.2289118", "isbn": "9781510614734", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2018-02-19", "pages": "Art. No. 104941H" }, { "id": "authors:wyfgp-cmh74", "collection": "authors", "collection_id": "wyfgp-cmh74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104553675", "type": "book_section", "title": "In vivo rat deep brain imaging using photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Lin", "given_name": "Li", "orcid": "0000-0002-0517-8436", "clpid": "Lin-Li" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Hu", "given_name": "Peng", "orcid": "0000-0002-2933-1239", "clpid": "Hu-Peng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The brain has been likened to a great stretch of unknown territory consisting of a number of unexplored continents. Small animal brain imaging plays an important role charting that territory. By using 1064 nm illumination from the side, we imaged the full coronal depth of rat brains in vivo. The experiment was performed using a real-time full-ring-array photoacoustic computed tomography (PACT) imaging system, which achieved an imaging depth of 11 mm and a 100 \u03bcm radial resolution. Because of the fast imaging speed of the full-ring-array PACT system, no animal motion artifact was induced. The frame rate of the system was limited by the laser repetition rate (50 Hz). In addition to anatomical imaging of the blood vessels in the brain, we continuously monitored correlations between the two brain hemispheres in one of the coronal planes. The resting states in the coronal plane were measured before and after stroke ligation surgery at a neck artery.", "doi": "10.1117/12.2251213", "isbn": "9781510605695", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2017-04-24", "pages": "Art. No. 1006406" }, { "id": "authors:q54x0-xvw56", "collection": "authors", "collection_id": "q54x0-xvw56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104553761", "type": "book_section", "title": "Synthetic light-needle photoacoustic microscopy for extended depth of field", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Yang", "given_name": "Jiamiao", "orcid": "0000-0003-0006-8411", "clpid": "Yang-Jiamiao" }, { "family_name": "Gong", "given_name": "Lei", "orcid": "0000-0002-0995-5781", "clpid": "Gong-Lei" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic microscopy (PAM) has been extensively applied in biomedical study because of its ability to visualize tissue morphology and physiology in vivo in three dimensions (3D). However, conventional PAM suffers from a rapidly decreasing resolution away from the focal plane because of the limited depth of focus of an objective lens, which deteriorates the volumetric imaging quality inevitably. Here, we propose a novel method to synthesize an ultra-long light needle to extend a microscope's depth of focus beyond its physical limitations with wavefront engineering method. Furthermore, it enables an improved lateral resolution that exceeds the diffraction limit of the objective lens. The virtual light needle can be flexibly synthesized anywhere throughout the imaging volume without mechanical scanning. Benefiting from these advantages, we developed a synthetic light needle photoacoustic microscopy (SLN-PAM) to achieve an extended depth of field (DOF), sub-diffraction and motionless volumetric imaging. The DOF of our SLN-PAM system is up to 1800 \u00b5m, more than 30-fold improvement over that gained by conventional PAM. Our system also achieves the lateral resolution of 1.8 \u00b5m (characterized at 532 nm and 0.1 NA objective), about 50% higher than the Rayleigh diffraction limit. Its superior imaging performance was demonstrated by 3D imaging of both non-biological and biological samples. This extended DOF, sub-diffraction and motionless 3D PAM will open up new opportunities for potential biomedical applications.", "doi": "10.1117/12.2256082", "isbn": "9781510605695", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2017-04-24", "pages": "Art. No. 1006428" }, { "id": "authors:aqdx0-n9231", "collection": "authors", "collection_id": "aqdx0-n9231", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-081618851", "type": "book_section", "title": "Imaging small animal whole-body dynamics by single-impulse panoramic photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Ma", "given_name": "Cheng", "clpid": "Ma-Cheng" }, { "family_name": "Lin", "given_name": "Li", "orcid": "0000-0002-0517-8436", "clpid": "Lin-Li" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Chen", "given_name": "Wanyi", "clpid": "Chen-Wanyi" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Small animal whole-body imaging, providing physiological, pathological, and phenotypical insights into biological\nprocesses, is indispensable in preclinical research. With high spatiotemporal resolution and functional contrast, small\nanimal imaging can visualize biological dynamics in vivo at whole-body scale, which can advance both fundamental\nbiology and translational medicine. However, current non-optical imaging techniques lack either spatiotemporal\nresolution or functional contrasts, and pure optical imaging suffers from either shallow penetration (up to ~1 mm) or a\npoor resolution-to-depth ratio (~1/3). Here, we present a standalone system, termed single-impulse panoramic\nphotoacoustic computed tomography (SIP-PACT), which overcomes all the above limitations. Our technology, with\nunprecedented performance, is envisioned to complement existing modalities for imaging entire small animals. As an\noptical imaging modality, SIP-PACT captures the high molecular contrast of endogenous substances such as\nhemoglobin, melanin, and lipid, as well as exogenous biomarkers, at the whole animal scale with full-view fidelity.\nUnlike other optical imaging methods, SIP-PACT sees through ~5 cm of tissue in vivo, and acquires cross-sectional\nimages with an in-plane resolution of ~100 \u03bcm. Such capabilities allow us to image, for the first time, mouse wholebody\ndynamics in real time with clear sub-organ anatomical and functional details and without motion artifacts. SIPPACT\ncan capture transients of whole-body oxygen saturation and pulse wave propagation in vivo without labeling. In\nsum, we expect widespread applications of SIP-PACT as a whole-body imaging tool for small animals in fundamental\nbiology, pharmacology, pathology, oncology, and other areas.", "doi": "10.1117/12.2251593", "isbn": "978-1-5106-0569-5", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03-23", "pages": "Art. No. 100640M" }, { "id": "authors:h13mz-9a638", "collection": "authors", "collection_id": "h13mz-9a638", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-083659632", "type": "book_section", "title": "Real-time photoacoustic flow cytography and photothermolysis of single circulating melanoma cells in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "He", "given_name": "Yun", "clpid": "He-Yun" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Huang", "given_name": "Chih-Hsien", "clpid": "Huang-Chih-Hsien" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Metastasis is responsible for as many as 90% of cancer-related deaths, and the deadliest skin cancer, melanoma, has a high propensity for metastasis. Since hematogenous spread of circulating tumor cells (CTCs) is cancer's main route of metastasis, detecting and destroying CTCs can impede metastasis and improve patients' prognoses. Extensive studies employing exogenous agents to detect tumor-specific biomarkers and guide therapeutics to CTCs have achieved promising results, but biosafety remains a critical concern. Taking another approach, physical detection and destruction of CTCs is a safer way to evaluate and reduce metastasis risks. Melanoma cells strongly express melanosomes, providing a striking absorption contrast with the blood background in the red to near-infrared spectrum. Exploiting this intrinsic optical absorption contrast of circulating melanoma cells, we coupled dual-wavelength photoacoustic flow cytography with a nanosecond-pulsed laser killing mechanism that specifically targets melanoma CTCs. We have successfully achieved in vivo label-free imaging of rare single CTCs and CTC clusters in mice. Further, the photoacoustic signal from a CTC immediately hardware-triggers a lethal pinpoint laser irradiation that lyses it on the spot in a thermally confined manner. Our technology can facilitate early inhibition of metastasis by clearing circulating tumor cells from vasculature.", "doi": "10.1117/12.2255068", "isbn": "978-1-5106-0569-5", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03-23", "pages": "Art. No. 100641E" }, { "id": "authors:bs10h-0t003", "collection": "authors", "collection_id": "bs10h-0t003", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-084927387", "type": "book_section", "title": "Linear-array-based photoacoustic tomography for label-free high throughput detection and quantification of circulating melanoma tumor cell clusters", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Ma", "given_name": "Jun", "clpid": "Ma-Jun" }, { "family_name": "Li", "given_name": "Yang", "orcid": "0000-0002-4939-8174", "clpid": "Li-Yang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Circulating tumor cell (CTC) clusters arise from multicellular grouping in the primary tumor and elevate the metastatic potential by 23 to 50 fold compared to single CTCs. High throughout detection and quantification of CTC clusters is critical for understanding the tumor metastasis process and improving cancer therapy. In this work, we report a linear-array-based photoacoustic tomography (LA-PAT) system capable of label-free high-throughput CTC cluster detection and quantification in vivo. LA-PAT detects CTC clusters and quantifies the number of cells in them based on the contrast-to-noise ratios (CNRs) of photoacoustic signals. The feasibility of LA-PAT was first demonstrated by imaging CTC clusters ex vivo. LA-PAT detected CTC clusters in the blood-filled microtubes and computed the number of cells in the clusters. The size distribution of the CTC clusters measured by LA-PAT agreed well with that obtained by optical microscopy. We demonstrated the ability of LA-PAT to detect and quantify CTC clusters in vivo by imaging injected CTC clusters in rat tail veins. LA-PAT detected CTC clusters immediately after injection as well as when they were circulating in the rat bloodstreams. Similarly, the numbers of cells in the clusters were computed based on the CNRs of the photoacoustic signals. The data showed that larger CTC clusters disappear faster than the smaller ones. The results prove the potential of LA-PAT as a promising tool for both preclinical tumor metastasis studies and clinical cancer therapy evaluation.", "doi": "10.1117/12.2252819", "isbn": "978-1-5106-0569-5", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03-03", "pages": "Art. No. 100641P" }, { "id": "authors:ysrhg-83447", "collection": "authors", "collection_id": "ysrhg-83447", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-110718457", "type": "book_section", "title": "Early-stage tumor detection using photoacoustic microscopy: a pattern recognition approach", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Yeh", "given_name": "Chenghung", "clpid": "Yeh-Chenghung" }, { "family_name": "Wang", "given_name": "Liang", "clpid": "Wang-Liang" }, { "family_name": "Liang", "given_name": "Jinyang", "clpid": "Liang-Jinyang" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Sohn", "given_name": "Rebecca E.", "clpid": "Sohn-R-E" }, { "family_name": "Arbeit", "given_name": "Jeffrey M.", "clpid": "Arbeit-J-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report photoacoustic microscopy (PAM) of arteriovenous (AV) shunts in early stage tumors in vivo, and develop a pattern recognition framework for computerized tumor detection. Here, using a high-resolution photoacoustic microscope, we implement a new blood oxygenation (sO_2)-based disease marker induced by the AV shunt effect in tumor angiogenesis. We discovered a striking biological phenomenon: There can be two dramatically different sO_2 values in bloodstreams flowing side-by-side in a single vessel. By tracing abnormal sO_2 values in the blood vessels, we can identify a tumor region at an early stage. To further automate tumor detection based on our findings, we adopt widely used pattern recognition methods and develop an efficient computerized classification framework. The test result shows over 80% averaged detection accuracy with false positive contributing 18.52% of error test samples on a 50 PAM image dataset.", "doi": "10.1117/12.2253529", "isbn": "9781510605695", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03-03", "pages": "Art. No. 100644N" }, { "id": "authors:61q37-8h156", "collection": "authors", "collection_id": "61q37-8h156", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-084558232", "type": "book_section", "title": "Quantitative photoacoustic elastography of Young's modulus in humans", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "author": [ { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Gong", "given_name": "Lei", "orcid": "0000-0002-0995-5781", "clpid": "Gong-Lei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Elastography can noninvasively map the elasticity distribution of biological tissue, which is often altered in pathological states. In this work, we report quantitative photoacoustic elastography (QPAE), capable of measuring Young's modulus of human tissue in vivo. By combining photoacoustic elastography with a stress sensor having known stress-strain behavior, QPAE can simultaneously measure strain and stress, from which Young's modulus is calculated. We first applied QPAE to quantify the Young's modulus of tissue-mimicking agar phantoms with different concentrations. The measured values fitted well with both the empirical expectations based on the agar concentrations and those measured in independent standard compression tests. We then demonstrated the feasibility of QPAE by measuring the Young's modulus of human skeletal muscle in vivo. The data showed a linear relationship between muscle stiffness and loading. The results proved that QPAE can noninvasively quantify the absolute elasticity of biological tissue, thus enabling longitudinal imaging of tissue elasticity. QPAE can be exploited for both preclinical biomechanics studies and clinical applications.", "doi": "10.1117/12.2252790", "isbn": "9781510605701", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03-03", "pages": "Art. No. 100640B" }, { "id": "authors:tkwzr-0he53", "collection": "authors", "collection_id": "tkwzr-0he53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-094754939", "type": "book", "title": "Photons Plus Ultrasound: Imaging and Sensing 2017", "editor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "[No abtract]", "isbn": "978-1-5106-0569-5", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2017-03" }, { "id": "authors:xz4js-35592", "collection": "authors", "collection_id": "xz4js-35592", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104554290", "type": "book_section", "title": "Grueneisen relaxation photoacoustic microscopy in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Ma", "given_name": "Jun", "clpid": "Ma-Jun" }, { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical-resolution photoacoustic microscopy (OR-PAM) can achieve submicron lateral resolution by tightly focusing the excitation light, while the axial resolution is still limited by the frequency bandwidth of the ultrasonic transducer. The Grueneisen relaxation effect, in which the Grueneisen parameter changes within the thermal relaxation time following a laser impulse heating, can provide excellent axial resolution due to its optical sectioning property. Based on this effect, Grueneisen relaxation photoacoustic microscopy (GR-PAM) was developed and demonstrated ex vivo. Here, we present for the first time in vivo imaging of mouse brains with improved axial resolution based on GR-PAM. An intensity-modulated continuous-wave (CW) 532 nm laser thermally heated the in-focus absorber. Another 532 nm pulsed laser, which is aligned confocally with the CW laser, generated the photoacoustic (PA) signal from the absorber. The difference between the amplitudes of the photoacoustic signals with and without heating was used for image reconstruction. The achieved axial resolution is ~12.5 \u00b5m, which is fivefold better than the acoustically determined value for a 20 MHz-bandwidth ultrasound transducer. The system was demonstrated by imaging a blood-filled tube ex vivo and blood vessels of mouse brains in vivo. The blood-filled tube diameter obtained from the PA image by GR-PAM is 105 \u00b5m, which is much closer to its actual diameter (100 \u00b5m) than the value from conventional OR-PAM (160 \u00b5m). This axial resolution improvement was further validated in imaging mouse brains in vivo, and yielded significantly narrower axial profiles of the vessels. This in vivo demonstration of imaging by GR-PAM might inspire more applications in PA biomedical imaging and sensing.", "doi": "10.1117/12.2211196", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-04-27", "pages": "Art. No. 97082Q" }, { "id": "authors:cg46z-t9371", "collection": "authors", "collection_id": "cg46z-t9371", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104554103", "type": "book_section", "title": "In vivo photoacoustic neuronal imaging of odor-evoked calcium signals in the drosophila brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Rong", "given_name": "Haoyang", "clpid": "Rong-Haoyang" }, { "family_name": "Raman", "given_name": "Baranidharan", "clpid": "Raman-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Neural scientists can benefit greatly from imaging tools that can penetrate thick brain tissue. Compared with traditional optical microscopy methods, photoacoustic imaging can beat the optical diffusion limit and achieve such deep tissue imaging with high spatial resolution. In this study, we used an optical-resolution photoacoustic microscope to image the odor-evoked neuronal activities in a drosophila model. Drosophila brain neurons stably express GCaMP5G, a calcium-sensitive fluorescent protein whose optical absorption coefficient changes with calcium influx during action potentials. We recorded an ~20% odor-evoked fractional photoacoustic signal increase at all depths of the drosophila brain in vivo, with and without removal of the brain cuticle, at a recording rate of 1 kHz. Our results were confirmed by concurrent fluorescent recordings. Furthermore, by performing fast 2D scanning, we imaged the antenna lobe region, which is of particular interest in neuroscience, at a volumetric rate of ~1 Hz with a sub-neuron resolution of 3 \uf06dm. Unlike optical imaging, which requires surgical removal of the scattering brain cuticle, our photoacoustic system can image through the cuticle and measure neuronal signals of the whole drosophila brain without invasive surgery, enabling minimal disturbance to the animal's behaviors. In conclusion, we have demonstrated photoacoustic imaging of calcium signals in drosophila brains for the first time. Utilizing the deep imaging capability of photoacoustic tomography, our methods could potentially be extended to in vivo imaging of neuronal activities from deep brains in other animal models.", "doi": "10.1117/12.2235935", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-04-27", "pages": "Art. No. 97082V" }, { "id": "authors:jxenn-1pq04", "collection": "authors", "collection_id": "jxenn-1pq04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104554377", "type": "book_section", "title": "In vivo microwave-based thermoacoustic tomography of rats", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Lin", "given_name": "Li", "orcid": "0000-0002-0517-8436", "clpid": "Lin-Li" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Microwave-based thermoacoustic tomography (TAT), based on the measurement of ultrasonic waves induced by microwave pulses, can reveal tissue dielectric properties that may be closely related to the physiological and pathological status of the tissues. Using microwaves as the excitation source improved imaging depth because of their deep penetration into biological tissues. We demonstrate, for the first time, in vivo microwave-based thermoacoustic imaging in rats. The transducer is rotated around the rat in a full circle, providing a full two-dimensional view. Instead of a flat ultrasonic transducer, we used a virtual line detector based on a cylindrically focused transducer. A 3 GHz microwave source with 0.6 \u00b5s pulse width and an electromagnetically shielded transducer with 2.25 MHz central frequency provided clear cross-sectional images of the rat's body. The high imaging contrast, based on the tissue's rate of absorption, and the ultrasonically defined spatial resolution combine to reveal the spine, kidney, muscle, and other deeply seated anatomical features in the rat's abdominal cavity. This non-invasive and non-ionizing imaging modality achieved an imaging depth beyond 6 cm in the rat's tissue. Cancer diagnosis based on information about tissue properties from microwave band TAT can potentially be more accurate than has previously been achievable.", "doi": "10.1117/12.2211053", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-04-27", "pages": "Art. No. 97080U" }, { "id": "authors:et5nc-7hp13", "collection": "authors", "collection_id": "et5nc-7hp13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104554204", "type": "book_section", "title": "Photoacoustic imaging of voltage signals", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical imaging of brain voltage signals is significantly limited in depth due to optical scattering and the absorptive property of brain tissue. Photoacoustic (PA) imaging promises to break this hard limit by utilizing both ballistic and diffused photons. To demonstrate the feasibility of PA, we used an in vivo mouse model. The brain cortex tissue was stained with dipicrylamine dye, electrically stimulated, and imaged with a customized dual-isosbestic-wavelength PA microscope (DIW-PAM). DIW-PAM separates voltage-induced PA signals from blood-induced PA signals and thereby allows recording the voltage response of mouse cortex tissue without interference from hemoglobin responses. The resting state PA voltage response signal exhibited a noise-like signal in the frequency domain. Upon 3 Hz electrical stimulation, the PA voltage response signal showed frequency peaks of 3.2 Hz and 6.3 Hz (Fig. 1). Although dipicrylamine dye is not fast enough for recording neuron action potentials, it served well for the purpose of this feasibility study. In conclusion, we successfully demonstrated in vivo photoacoustic imaging of mouse brain voltage signals for the first time. If a fast voltage-sensitive dye is available, using photoacoustic computed tomography (PACT) instead of PA microscopy could allow acquiring full-field PA action potential images at a speed limited only by the laser pulse repetition rate.", "doi": "10.1117/12.2211747", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-04-27", "pages": "Art. No. 97081U" }, { "id": "authors:0dzcq-m9j36", "collection": "authors", "collection_id": "0dzcq-m9j36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-104554457", "type": "book_section", "title": "Multi-view Hilbert transformation in full-ring-transducer-array based photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography (PAT) exploits optical contrast and ultrasonic detection principles to form images of absorbed optical energy density within tissue. Based on the photoacoustic effect, PAT directly and quantitatively measures specific optical absorption. A full-ring ultrasonic transducer array based photoacoustic computed tomography (PACT) system was recently developed for small animal whole-body imaging with a full-view detection angle and high in-plane resolution (100 \u00b5m). However, due to the band-pass frequency response of the piezoelectric transducer elements, the reconstructed images present bipolar (both positive and negative) pixel values, which is artificial and counterintuitive for physicians and biologists seeking to interpret the image. Moreover, bipolar pixel values hinder quantification of physiological parameters, such as oxygen saturation and blood flow speed. Unipolar images can be obtained by deconvolving the raw channel data with the transducer's electrical impulse response and applying non-negativity during iteration, but this process requires complex transducer modeling and time-consuming computation. Here, we present a multi-view Hilbert transformation method to recover the unipolar initial pressure for full-ring PACT. Multi-view Hilbert transformation along the acoustic wave propagation direction minimizes reconstruction artifacts during envelope extraction and maintains the signal-to-noise ratio of the reconstructed images. The in-plane isotropic spatial resolution of this method was quantified to 168 \u03bcm within a 20 \u00d7 20 mm2 field of view. The effectiveness of the proposed algorithm was first validated by numerical simulations and then demonstrated with ex-vivo mouse brain structural imaging and in-vivo mouse wholebody imaging.", "doi": "10.1117/12.2212662", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-04-27", "pages": "Art. No. 97082C" }, { "id": "authors:7pxz6-ge654", "collection": "authors", "collection_id": "7pxz6-ge654", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-140924685", "type": "book_section", "title": "Reversibly switchable photoacoustic tomography using a genetically encoded near-infrared phytochrome", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Kaberniuk", "given_name": "Andrii A.", "clpid": "Kaberniuk-A-A" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Shcherbakova", "given_name": "Daria M.", "clpid": "Shcherbakova-D-M" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Verkhusha", "given_name": "Vladislav V.", "orcid": "0000-0002-2083-8121", "clpid": "Verkhusha-V-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical imaging of genetically encoded probes has revolutionized biomedical studies by providing valuable information about targeted biological processes. Here, we report a novel imaging technique, termed reversibly switchable photoacoustic tomography (RS-PAT), which exhibits large penetration depth, high detection sensitivity, and super-resolution. RS-PAT combines advanced photoacoustic imaging techniques with, for the first time, a nonfluorescent photoswitchable bacterial phytochrome. This bacterial phytochrome is the most near-infrared shifted genetically encoded probe reported so far. Moreover, this bacterial phytochrome is reversibly photoconvertible between its far-red and near-infrared light absorption states. Taking maximum advantage of the powerful imaging capability of PAT and the unique photochemical properties of the phytochrome, RS-PAT has broken through both the optical diffusion limit for deep-tissue imaging and the optical diffraction limit for super-resolution photoacoustic microscopy. Specifically, with RS-PAT we have achieved an unprecedented detection sensitivity of ~2 \u03bcM, or as few as ~20 tumor cells, at a centimeter depth. Such high sensitivity is fully demonstrated in our study by monitoring tumor growth and metastasis at whole-body level with ~100 \u03bcm resolution. Moreover, our microscopic implementation of RS-PAT is capable of imaging mammalian cells with a sub-diffraction lateral resolution of ~140 nm and axial resolution of ~400 nm, which are respectively ~2-fold and ~75-fold finer than those of our conventional photoacoustic microscopy. Overall, RS-PAT is a new and promising imaging technology for studying biological processes at different length scales.", "doi": "10.1117/12.2229156", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-18", "pages": "Art. No. 97082U" }, { "id": "authors:j7dj8-kg421", "collection": "authors", "collection_id": "j7dj8-kg421", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-143330495", "type": "book_section", "title": "Compensation for acoustic heterogeneities in photoacoustic computed tomography using a variable temporal data truncation reconstruction method", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Poudel", "given_name": "Joemini", "clpid": "Poudel-J" }, { "family_name": "Matthews", "given_name": "Thomas P.", "clpid": "Matthews-T-P" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. If the object possesses spatially variant acoustic properties that are unaccounted for by the reconstruction algorithm, the estimated image can contain distortions. While reconstruction algorithms have recently been developed for compensating for this effect, they generally require the objects acoustic properties to be known a priori. To circumvent the need for detailed information regarding an objects acoustic properties, we have previously proposed a half-time reconstruction method for PACT. A half-time reconstruction method estimates the PACT image from a data set that has been temporally truncated to exclude the data components that have been strongly aberrated. In this approach, the degree of temporal truncation is the same for all measurements. However, this strategy can be improved upon it when the approximate sizes and locations of strongly heterogeneous structures such as gas voids or bones are known. In this work, we investigate PACT reconstruction algorithms that are based on a variable temporal data truncation (VTDT) approach that represents a generalization of the half-time reconstruction approach. In the VTDT approach, the degree of temporal truncation for each measurement is determined by the distance between the corresponding transducer location and the nearest known bone or gas void location. Reconstructed images from a numerical phantom is employed to demonstrate the feasibility and effectiveness of the approach.", "doi": "10.1117/12.2213416", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 97083W" }, { "id": "authors:8hrt0-ppt70", "collection": "authors", "collection_id": "8hrt0-ppt70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-090249745", "type": "book_section", "title": "Compensation for air voids in photoacoustic computed tomography image reconstruction", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Matthews", "given_name": "Thomas P.", "clpid": "Matthews-T-P" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Most image reconstruction methods in photoacoustic computed tomography (PACT) assume that the acoustic properties of the object and the surrounding medium are homogeneous. This can lead to strong artifacts in the reconstructed images when there are significant variations in sound speed or density. Air voids represent a particular challenge due to the severity of the differences between the acoustic properties of air and water. In whole-body small animal imaging, the presence of air voids in the lungs, stomach, and gastrointestinal system can limit image quality over large regions of the object. Iterative reconstruction methods based on the photoacoustic wave equation can account for these acoustic variations, leading to improved resolution, improved contrast, and a reduction in the number of imaging artifacts. However, the strong acoustic heterogeneities can lead to instability or errors in the numerical wave solver. Here, the impact of air voids on PACT image reconstruction is investigated, and procedures for their compensation are proposed. The contributions of sound speed and density variations to the numerical stability of the wave solver are considered, and a novel approach for mitigating the impact of air voids while reducing the computational burden of image reconstruction is identified. These results are verified by application to an experimental phantom.", "doi": "10.1117/12.2213307", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 970841" }, { "id": "authors:m396p-3xs93", "collection": "authors", "collection_id": "m396p-3xs93", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-100350169", "type": "book_section", "title": "Vascular elastic photoacoustic tomography in humans", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Hai", "given_name": "Pengfei", "clpid": "Hai-Pengfei" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Liang", "given_name": "Jinyang", "clpid": "Liang-Jinyang" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Quantification of vascular elasticity can help detect thrombosis and prevent life-threatening conditions such as acute myocardial infarction or stroke. Here, we propose vascular elastic photoacoustic tomography (VE-PAT) to measure vascular elasticity in humans. VE-PAT was developed by incorporating a linear-array-based photoacoustic computed tomography system with a customized compression stage. By measuring the deformation of blood vessels under uniaxial loading, VE-PAT was able to quantify the vascular compliance. We first demonstrated the feasibility of VE-PAT in blood vessel phantoms. In large vessel phantoms, VE-PAT detected a decrease in vascular compliance due to simulated thrombosis, which was validated by a standard compression test. In small blood vessel phantoms embedded 3 mm deep in gelatin, VE-PAT detected elasticity changes at depths that are difficult to image using other elasticity imaging techniques. We then applied VE-PAT to assess vascular compliance in a human subject and detected a decrease in vascular compliance when an occlusion occurred downstream from the measurement point, demonstrating the potential of VE-PAT in clinical applications such as detection of deep venous thrombosis.", "doi": "10.1117/12.2219700", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 970803" }, { "id": "authors:8sbyh-er937", "collection": "authors", "collection_id": "8sbyh-er937", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-095437537", "type": "book_section", "title": "Detecting both melanoma depth and volume in vivo with a handheld photoacoustic probe", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Cornelius", "given_name": "Lynn A.", "clpid": "Cornelius-L-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We applied a linear-array-based photoacoustic probe to detect the tumor depth and volume of melanin-containing melanoma in nude mice in vivo. We demonstrated the ability of this linear-array-based system to measure both the depth and volume of melanoma through phantom, ex vivo, and in vivo experiments. The volume detection ability also enables us to accurately calculate the rate of growth of the tumor, which is important in quantifying tumor activity. Our results show that this system can be used for clinical melanoma diagnosis and treatment at the bedside.", "doi": "10.1117/12.2213245", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 970806" }, { "id": "authors:qxgph-shh49", "collection": "authors", "collection_id": "qxgph-shh49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-142432014", "type": "book_section", "title": "Bessel beam Grueneisen photoacoustic microscopy with extended depth of field", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Shi", "given_name": "Junhui", "orcid": "0000-0002-5741-2781", "clpid": "Shi-Junhui" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Noordam", "given_name": "Cedric", "clpid": "Noordam-C" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The short focal depth of a Gaussian beam limits the volumetric imaging speed of optical resolution photoacoustic microscopy (OR-PAM). A Bessel beam, which is diffraction-free, provides a long focal depth, but its side-lobes may deteriorate image quality when the Bessel beam is directly employed to excite photoacoustic signals in ORPAM. Here, we present a nonlinear approach based on the Grueneisen relaxation effect to suppress the side-lobe artifacts in photoacoustic imaging. This method extends the focal depth of OR-PAM and speeds up volumetric imaging. We experimentally demonstrated a 1-mm focal depth with a 7-\u03bcm lateral resolution and volumetrically imaged a carbon fiber and red blood cell samples.", "doi": "10.1117/12.2211198", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 97083H" }, { "id": "authors:cp6nt-9qp11", "collection": "authors", "collection_id": "cp6nt-9qp11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-140234611", "type": "book_section", "title": "In vivo photoacoustic flowmetry in the optical diffusive regime based on saline injection", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2016", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Poudel", "given_name": "Joemini", "clpid": "Poudel-J" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We propose a saline-injection-based method to quantify blood flow velocity in vivo with acoustic-resolution photoacoustic tomography. By monitoring the saline-blood-interface propagating in the blood vessel, we can resolve the flow velocity. In phantom experiments, a root-mean-squared error of prediction of 0.29 mm/s was achieved. By injecting saline into a mouse tail vein covered with 1 mm chicken tissue, we showed that the flow velocity in the tail vein could be measured at depth, which is especially pertinent to monitoring blood flow velocity in patients undergoing intravenous infusion.", "doi": "10.1117/12.2217468", "isbn": "9781628419429", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2016-03-15", "pages": "Art. No. 97084U" }, { "id": "authors:9wzqy-qgb25", "collection": "authors", "collection_id": "9wzqy-qgb25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-090451148", "type": "book_section", "title": "Photon-phonon synergy: photoacoustic tomography and beyond", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography is expected to impact biology and medicine broadly by providing multiscale in vivo functional and molecular imaging of structures ranging from subcellular organelles to organs, enabling a noninvasive look at subcutaneous tissue at a deep level. Lihong Wang holds the Gene K. Beare Distinguished Professorship of Biomedical Engineering at Washington University in St. Louis, and is Editor-in-Chief of the Journal of Biomedical Optics. Wang was awarded the 2015 Britton Chance Biomedical Optics Award for his pioneering technical contributions and visionary leadership in the development and application of photoacoustic tomography, photoacoustic microscopy, and photon transport modeling.", "doi": "10.1117/12.2197205", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-04-22", "pages": "Art. No. 93235K" }, { "id": "authors:k3gw5-61z02", "collection": "authors", "collection_id": "k3gw5-61z02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-101245704", "type": "book_section", "title": "In vivo deep brain imaging of rats using oral-cavity illuminated photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Lin", "given_name": "Li", "orcid": "0000-0002-0517-8436", "clpid": "Lin-Li" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wong", "given_name": "Terence T. W.", "orcid": "0000-0001-6399-758X", "clpid": "Wong-Terence-T-W" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We demonstrate, by means of internal light delivery, photoacoustic imaging of the deep brain of rats in vivo. With fiber illumination via the oral cavity, we delivered light directly into the bottom of the brain, much more than can be delivered by external illumination. The study was performed using a photoacoustic computed tomography (PACT) system equipped with a 512-element full-ring transducer array, providing a full two-dimensional view aperture. Using internal illumination, the PACT system provided clear cross sectional photoacoustic images from the palate to the middle brain of live rats, revealing deep brain structures such as the hypothalamus, brain stem, and cerebral medulla.", "doi": "10.1117/12.2076482", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93230G" }, { "id": "authors:xbp3z-dvq55", "collection": "authors", "collection_id": "xbp3z-dvq55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-161553096", "type": "book_section", "title": "Catheter-based photoacoustic endoscope for use in the instrument channel of a clinical video endoscope", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have successfully developed a fully-sheathed, flexible shaft-based, mechanical scanning photoacoustic endoscopy (PAE) system for imaging the human gastrointestinal tract via the instrument channel of a clinical video endoscope. The endoscopic system uses a single element ultrasonic transducer and flexible shaft-based proximal actuation mechanism, and it has a 2.5 m long and 3.2 mm diameter catheter section, which can be accommodated in the 3.7 mm diameter instrument channel of a clinical video endoscope. Here, we demonstrate the intra-instrument channel workability and in vivo imaging capability of the PAE system.", "doi": "10.1117/12.2080094", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93230Y" }, { "id": "authors:c13c7-c1q18", "collection": "authors", "collection_id": "c13c7-c1q18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-151246491", "type": "book_section", "title": "Photo-imprint super-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Combining the absorption-based photoacoustic effect and intensity-dependent photobleaching effect, we demonstrate a simple method for super-resolution photoacoustic imaging of both fluorescent and non-fluorescent samples. Our method is based on a double-excitation process, where the first excitation pulse partially and inhomogeneously bleaches the molecules in the diffraction-limited excitation volume, thus biasing the signal contributions from a second excitation pulse striking the same region. By scanning the excitation beam, we performed three-dimensional sub-diffraction imaging of varied fluorescent and non-fluorescent species. A lateral resolution of 80 nm and an axial resolution of 370 nm have been demonstrated. This technique has the potential to enable label-free super-resolution imaging, and can be transferred to other optical imaging modalities or combined with other super-resolution methods.", "doi": "10.1117/12.2077350", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932327" }, { "id": "authors:we4f5-ser14", "collection": "authors", "collection_id": "we4f5-ser14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-103744023", "type": "book_section", "title": "Photoacoustic computed tomography without accurate ultrasonic transducer responses", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Sheng", "given_name": "Qiwei", "clpid": "Sheng-Qiwei" }, { "family_name": "Wang", "given_name": "Kun", "clpid": "Wang-Kun" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Conventional photoacoustic computed tomography (PACT) image reconstruction methods assume that the object and surrounding medium are described by a constant speed-of-sound (SOS) value. In order to accurately recover fine structures, SOS heterogeneities should be quantified and compensated for during PACT reconstruction. To address this problem, several groups have proposed hybrid systems that combine PACT with ultrasound computed tomography (USCT). In such systems, a SOS map is reconstructed first via USCT. Consequently, this SOS map is employed to inform the PACT reconstruction method. Additionally, the SOS map can provide structural information regarding tissue, which is complementary to the functional information from the PACT image. We propose a paradigm shift in the way that images are reconstructed in hybrid PACT-USCT imaging. Inspired by our observation that information about the SOS distribution is encoded in PACT measurements, we propose to jointly reconstruct the absorbed optical energy density and SOS distributions from a combined set of USCT and PACT measurements, thereby reducing the two reconstruction problems into one. This innovative approach has several advantages over conventional approaches in which PACT and USCT images are reconstructed independently: (1) Variations in the SOS will automatically be accounted for, optimizing PACT image quality; (2) The reconstructed PACT and USCT images will possess minimal systematic artifacts because errors in the imaging models will be optimally balanced during the joint reconstruction; (3) Due to the exploitation of information regarding the SOS distribution in the full-view PACT data, our approach will permit high-resolution reconstruction of the SOS distribution from sparse array data.", "doi": "10.1117/12.2081056", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932313" }, { "id": "authors:xeapw-06y82", "collection": "authors", "collection_id": "xeapw-06y82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-102200187", "type": "book_section", "title": "Photoacoustic microscopy of complex regional pain syndrome type I (CRPS-1) after stellate ganglion blocks in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Yi", "given_name": "Xiaobin", "clpid": "Yi-Xiaobin" }, { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We used photoacoustic microscopy (PAM) to assist diagnoses and monitor the progress and treatment outcome of complex regional pain syndrome type 1 (CRPS-1). Blood vasculature and oxygen saturation (sO_2) were imaged by PAM in eight adult patients with CRPS-1. Patients' hands and cuticles were imaged both before and after stellate ganglion block (SGB) for comparison. For all patients, both the vascular structure and sO_2 could be assessed by PAM. In addition, more vessels and stronger signals were observed after SGB.", "doi": "10.1117/12.2076691", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932338" }, { "id": "authors:03ktp-5sp75", "collection": "authors", "collection_id": "03ktp-5sp75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-103014208", "type": "book_section", "title": "Photoacoustic imaging of single circulating melanoma cells in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Xu", "given_name": "Song", "clpid": "Xu-Song" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Melanoma, one of the most common types of skin cancer, has a high mortality rate, mainly due to a high propensity for tumor metastasis. The presence of circulating tumor cells (CTCs) is a potential predictor for metastasis. Label-free imaging of single circulating melanoma cells in vivo provides rich information on tumor progress. Here we present photoacoustic microscopy of single melanoma cells in living animals. We used a fast-scanning optical-resolution photoacoustic microscope to image the microvasculature in mouse ears. The imaging system has sub-cellular spatial resolution and works in reflection mode. A fast-scanning mirror allows the system to acquire fast volumetric images over a large field of view. A 500-kHz pulsed laser was used to image blood and CTCs. Single circulating melanoma cells were imaged in both capillaries and trunk vessels in living animals. These high-resolution images may be used in early detection of CTCs with potentially high sensitivity. In addition, this technique enables in vivo study of tumor cell extravasation from a primary tumor, which addresses an urgent pre-clinical need.", "doi": "10.1117/12.2076987", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93230A" }, { "id": "authors:q2zp9-fc360", "collection": "authors", "collection_id": "q2zp9-fc360", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-083752988", "type": "book_section", "title": "Synergistic image reconstruction for hybrid ultrasound and photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Matthews", "given_name": "Thomas P.", "clpid": "Matthews-T-P" }, { "family_name": "Wang", "given_name": "Kun", "clpid": "Wang-Kun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Conventional photoacoustic computed tomography (PACT) image reconstruction methods assume that the object and surrounding medium are described by a constant speed-of-sound (SOS) value. In order to accurately recover fine structures, SOS heterogeneities should be quantified and compensated for during PACT reconstruction. To address this problem, several groups have proposed hybrid systems that combine PACT with ultrasound computed tomography (USCT). In such systems, a SOS map is reconstructed first via USCT. Consequently, this SOS map is employed to inform the PACT reconstruction method. Additionally, the SOS map can provide structural information regarding tissue, which is complementary to the functional information from the PACT image. We propose a paradigm shift in the way that images are reconstructed in hybrid PACT-USCT imaging. Inspired by our observation that information about the SOS distribution is encoded in PACT measurements, we propose to jointly reconstruct the absorbed optical energy density and SOS distributions from a combined set of USCT and PACT measurements, thereby reducing the two reconstruction problems into one. This innovative approach has several advantages over conventional approaches in which PACT and USCT images are reconstructed independently: (1) Variations in the SOS will automatically be accounted for, optimizing PACT image quality; (2) The reconstructed PACT and USCT images will possess minimal systematic artifacts because errors in the imaging models will be optimally balanced during the joint reconstruction; (3) Due to the exploitation of information regarding the SOS distribution in the full-view PACT data, our approach will permit high-resolution reconstruction of the SOS distribution from sparse array data.", "doi": "10.1117/12.2081048", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93233A" }, { "id": "authors:n63rt-37p60", "collection": "authors", "collection_id": "n63rt-37p60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180907-085555777", "type": "book_section", "title": "DMD-based spatially Fourier-encoded photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Liang", "given_name": "Jinyang", "clpid": "Liang-Jinyang" }, { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device (DMD). The spatial fluence distribution of laser pulses is Fourier-encoded by the DMD, and a series of such encoded photoacoustic (PA) measurements enables decoding of the spatial distribution of optical absorption. By imaging a chromium target, we demonstrated the throughput and Fellgett advantages, which increased the PA signal-to-noise ratio (SNR) compared to raster scanning. The system was used to image two biological targets, a monolayer of red blood cells, and melanoma cells. The enhanced SNR benefited PA images by increasing the image's contrast-to-noise ratio and target identifiability.", "doi": "10.1117/12.2076783", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932324" }, { "id": "authors:m5q37-63047", "collection": "authors", "collection_id": "m5q37-63047", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-102322999", "type": "book_section", "title": "Image reconstruction in transcranial photoacoustic computed tomography of the brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Mitsuhashi", "given_name": "Kenji", "clpid": "Mitsuhashi-Kenji" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) holds great promise for transcranial brain imaging. However, the strong reflection, scattering, attenuation, and mode-conversion of photoacoustic waves in the skull pose serious challenges to establishing the method. The lack of an appropriate model of solid media in conventional PACT imaging models, which are based on the canonical scalar wave equation, causes a significant model mismatch in the presence of the skull and thus results in deteriorated reconstructed images. The goal of this study was to develop an image reconstruction algorithm that accurately models the skull and thereby ameliorates the quality of reconstructed images. The propagation of photoacoustic waves through the skull was modeled by a viscoelastic stress tensor wave equation, which was subsequently discretized by use of a staggered grid fourth-order finite-difference time-domain (FDTD) method. The matched adjoint of the FDTD-based wave propagation operator was derived for implementing a back-projection operator. Systematic computer simulations were conducted to demonstrate the effectiveness of the back-projection operator for reconstructing images in a realistic three-dimensional PACT brain imaging system. The results suggest that the proposed algorithm can successfully reconstruct images from transcranially-measured pressure data and readily be translated to clinical PACT brain imaging applications.", "doi": "10.1117/12.2081050", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93233B" }, { "id": "authors:m110n-kgh44", "collection": "authors", "collection_id": "m110n-kgh44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-155413834", "type": "book_section", "title": "In vivo melanoma depth detection by a handheld photoacoustic microscope", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Cornelius", "given_name": "Lynn A.", "clpid": "Cornelius-L-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We developed a handheld photoacoustic microscope (PAM) to detect melanoma and determine tumor depth in nude mice in vivo. Compared to our previous PAM system for melanoma imaging, a new light delivery mechanism is introduced to improve light penetration. We show that melanomas with 4.1 mm and 3.3 mm thicknesses can be successfully detected in phantom and in vivo experiments, respectively. With its deep melanoma imaging ability and novel handheld design, this system is promising for clinical melanoma diagnosis, prognosis, and surgical planning for patients at the bedside.", "doi": "10.1117/12.2076684", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932304" }, { "id": "authors:spng5-98s44", "collection": "authors", "collection_id": "spng5-98s44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-132431682", "type": "book_section", "title": "Noninvasive photoacoustic microscopy of methemoglobin in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Tang", "given_name": "Min", "clpid": "Tang-Min" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Various causes can lead to methemoglobinemia, and it has the potential to be confused with other diseases. In vivo measurements of methemoglobin have significant applications in the clinics. We quantified the average and the distributed percentage of methemoglobin both in vitro and in vivo using photoacoustic microscopy (PAM). Based on the absorption spectra of methemoglobin, oxyhemoglobin, and deoxyhemoglobin, three wavelengths were chosen to differentiate methemoglobin from the others. We imaged the methemoglobin percentage in microtubes that mimicked blood vessels as a phantom experiment. The methemoglobin concentrations calculated from the photoacoustic signals were in accordance with the preset concentrations. We also demonstrated the ability of PAM to quantitatively image methemoglobin distribution in vivo in a mouse ear.", "doi": "10.1117/12.2076692", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93233K" }, { "id": "authors:1dfsa-z7g72", "collection": "authors", "collection_id": "1dfsa-z7g72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-160424903", "type": "book_section", "title": "Isotropic-resolution linear-array-based photoacoustic computed tomography through inverse Radon transform", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Xian", "given_name": "Jun", "clpid": "Xian-Jun" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.", "doi": "10.1117/12.2076660", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93230I" }, { "id": "authors:snphd-8sk81", "collection": "authors", "collection_id": "snphd-8sk81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-151522956", "type": "book_section", "title": "Amplitude-masked photoacoustic wavefront shaping: theory and application in flowmetry", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Liang", "given_name": "Jinyang", "clpid": "Liang-Jinyang" }, { "family_name": "Tay", "given_name": "Jian Wei", "clpid": "Tay-Jian-Wei" }, { "family_name": "Hemphill", "given_name": "Ashton S.", "clpid": "Hemphill-A-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical diffusion in scattering media prevents focusing beyond shallow depths, causing optical imaging and sensing to suffer from low optical intensities, resulting in low signal-to-noise ratios (SNR). Here, we demonstrate focusing using a fast binary-amplitude digital micromirror device to characterize the transmission modes of the scattering medium. We then identify and selectively illuminate the transmission modes which contribute constructively to the intensity at the optical focus. Applying this method to photoacoustic flowmetry, we increased the optical intensity at the focus six-fold, and showed that the corresponding increase in SNR allows particle flow to be measured.", "doi": "10.1117/12.2081693", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932310" }, { "id": "authors:1nb3y-jxz02", "collection": "authors", "collection_id": "1nb3y-jxz02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-103207443", "type": "book_section", "title": "Three-dimensional photoacoustic and ultrasonic endoscopic imaging of two rabbit esophagi", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The addition of photoacoustic endoscopy to conventional endoscopic ultrasound offers imaging capabilities that may improve diagnosis and clinical care of gastrointestinal tract diseases. In this study, using a 3.8-mm diameter dual-mode photoacoustic and ultrasonic endoscopic probe, we investigated photoacoustic and ultrasonic image features of rabbit esophagi. Specifically, we performed ex vivo imaging of intact rabbit esophagi and correlated the acquired images with histology. Without motion artifact-based limitations, we were able to utilize the full resolving power of the endoscopic device and acquire the first three-dimensional vasculature map of the esophagus and mediastinum, along with coregistered tissue density information. Here, we present the experimental results and discuss potential clinical applications of the technique.", "doi": "10.1117/12.2080294", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932334" }, { "id": "authors:ej9n4-pnm14", "collection": "authors", "collection_id": "ej9n4-pnm14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-133542965", "type": "book_section", "title": "A micromachined silicon parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Cho", "given_name": "Young", "clpid": "Cho-Young" }, { "family_name": "Chang", "given_name": "Cheng-Chung", "clpid": "Chang-Cheng-Chung" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To achieve real-time photoacoustic tomography (PAT), massive transducer arrays and data acquisition (DAQ) electronics are needed to receive the PA signals simultaneously, which results in complex and high-cost ultrasound receiver systems. To address this issue, we have developed a new PA data acquisition approach using acoustic time delay. Optical fibers were used as parallel acoustic delay lines (PADLs) to create different time delays in multiple channels of PA signals. This makes the PA signals reach a single-element transducer at different times. As a result, they can be properly received by single-channel DAQ electronics. However, due to their small diameter and fragility, using optical fiber as acoustic delay lines poses a number of challenges in the design, construction and packaging of the PADLs, thereby limiting their performances and use in real imaging applications. In this paper, we report the development of new silicon PADLs, which are directly made from silicon wafers using advanced micromachining technologies. The silicon PADLs have very low acoustic attenuation and distortion. A linear array of 16 silicon PADLs were assembled into a handheld package with one common input port and one common output port. To demonstrate its real-time PAT capability, the silicon PADL array (with its output port interfaced with a single-element transducer) was used to receive 16 channels of PA signals simultaneously from a tissue-mimicking optical phantom sample. The reconstructed PA image matches well with the imaging target. Therefore, the silicon PADL array can provide a 16\u00d7 reduction in the ultrasound DAQ channels for real-time PAT.", "doi": "10.1117/12.2080178", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93232Z" }, { "id": "authors:4jjes-q4f58", "collection": "authors", "collection_id": "4jjes-q4f58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180910-161005322", "type": "book_section", "title": "Label-free structural photoacoustic tomography of intact mouse brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Capitalizing on endogenous hemoglobin contrast, photoacoustic computed tomography (PACT), a deep-tissue highresolution imaging modality, has drawn increasing interest in neuro-imaging. However, most existing studies are limited to functional imaging on the cortical surface, and the deep-brain structural imaging capability of PACT has never been demonstrated. Here, we explicitly studied the limiting factors of deep-brain PACT imaging. We found that the skull distorted the acoustic signal and blood suppressed the structural contrast from other chromophores. When the two effects are mitigated, PACT can provide high-resolution label-free structural imaging through the entire mouse brain. With 100 \u03bcm in-plane resolution, we can clearly identify major structures of the brain, and the image quality is comparable to that of magnetic resonance microscopy. Spectral PACT studies indicate that structural contrasts mainly originate from cytochrome and lipid. The feasibility of imaging the structure of the brain in vivo has also been discussed. Our results demonstrate that PACT is a promising modality for both structural and functional brain imaging.", "doi": "10.1117/12.2077236", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93230M" }, { "id": "authors:fsbtv-5v040", "collection": "authors", "collection_id": "fsbtv-5v040", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-084310940", "type": "book_section", "title": "Optical-resolution photoacoustic microscopy of the metabolic rate of oxygen in a mouse renal tumor model", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Yeh", "given_name": "Chenghung", "clpid": "Yeh-Chenghung" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Liang", "given_name": "Jinyang", "clpid": "Liang-Jinyang" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Soetikno", "given_name": "Brian", "clpid": "Soetikno-B" }, { "family_name": "Lu", "given_name": "Zhi Hong", "clpid": "Lu-Zhi-Hong" }, { "family_name": "Sohn", "given_name": "Rebecca E.", "clpid": "Sohn-R-E" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Arbeit", "given_name": "Jeffrey M.", "clpid": "Arbeit-J-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We propose using noninvasive longitudinal optical-resolution photoacoustic microscopy (L-ORPAM) to quantify blood flow flux, oxygen saturation (sO_2), and thereby the metabolic rate of oxygen (MRO_2), for a renal tumor model in the same mouse over weeks to months. Experiments showed that the sO2 difference between the artery and vein decreased greatly due to the arteriovenous shunting effect during tumor growth. Moreover, hypermetabolism was exhibited by an increase in MRO_2.", "doi": "10.1117/12.2082948", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 93233H" }, { "id": "authors:4ppy5-8ae78", "collection": "authors", "collection_id": "4ppy5-8ae78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180905-143111348", "type": "book_section", "title": "Label-free optical-resolution photoacoustic endomicroscopy in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2015", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Yeh", "given_name": "Cheng-Hung", "clpid": "Yeh-Cheng-Hung" }, { "family_name": "Danielli", "given_name": "Amos", "clpid": "Danielli-A" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Intravital microscopy techniques have become increasingly important in biomedical research because they can provide unique microscopic views of various biological or disease developmental processes in situ. Here we present an optical-resolution photoacoustic endomicroscopy (OR-PAEM) system that visualizes internal organs with a much finer resolution than conventional acoustic-resolution photoacoustic endoscopy systems. By combining gradient index (GRIN) lens-based optical focusing and ultrasonic ring transducer-based acoustic focusing, we achieved a transverse resolution as fine as ~10 \u03bcm at an optical working distance of 6.5 mm. The OR-PAEM system's high-resolution intravital imaging capability is demonstrated through animal experiments.", "doi": "10.1117/12.2080224", "isbn": "9781628414134", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2015-03-11", "pages": "Art. No. 932332" }, { "id": "authors:v2hzt-64h41", "collection": "authors", "collection_id": "v2hzt-64h41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-100734622", "type": "book_section", "title": "A handheld optical fiber parallel acoustic delay line (PADL) probe for photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Cho", "given_name": "Young", "clpid": "Cho-Young" }, { "family_name": "Chang", "given_name": "Cheung-Chung", "clpid": "Chang-Cheung-Chung" }, { "family_name": "Jeon", "given_name": "Mansik", "clpid": "Jeon-Mansik" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In current photoacoustic tomography (PAT), l-D or 2-D ultrasound arrays and multi-channel data acquisition (DAQ) electronics are used to detect the photoacoustic signals simultaneously for \"real-time\" image construction. However, as the number of transducer elements and DAQ channels increase, the construction and operation of the ultrasound receiving system will become complex and costly. This situation can be addressed by using parallel acoustic delay lines (PADLs) to create true time delays in multiple PA signal channels. The time-delayed PA signals will reach the ultrasound transducer at different times and therefore can be received by one single-element transducer without mixing with each other. In this paper, we report the development of the first miniaturized PADL probe suitable for handheld operations. Fusedsilica optical fibers with low acoustic attenuation were used to construct the 16 PADLs with specific time delays. The handheld probe structure was fabricated using precision laser-micromachining process to provide robust mechanical support and accurate alignment of the PADLs with minimal acoustic distortion and inter-channel coupling. The 16 optical-fiber PADLs were arranged to form one input port and two output ports. Photoacoustic imaging of a black-ink target embedded in an optically-scattering phantom was successfully conducted using the handheld PADL probe with two single-element transducers and two DAQ channels (equal to a channel reduction ratio of 8:1). Our results show that the PADL technique and the handheld probe could provide a promising solution for real-time PAT with significantly reduced complexity and cost of the ultrasound receiver system.", "doi": "10.1117/12.2037870", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89432W" }, { "id": "authors:rkz60-36z66", "collection": "authors", "collection_id": "rkz60-36z66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059756", "type": "book_section", "title": "Resting-state functional connectivity imaging of the mouse brain using photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Nasiriavanaki", "given_name": "Mohammadreza", "clpid": "Nasiriavanaki-M" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wan", "given_name": "Hanlin", "clpid": "Wan-Hanlin" }, { "family_name": "Bauer", "given_name": "Adam Q.", "clpid": "Bauer-A-Q" }, { "family_name": "Culver", "given_name": "Joseph P.", "clpid": "Culver-J-P" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Resting-state functional connectivity (RSFC) imaging is an emerging neuroimaging approach that aims to identify spontaneous cerebral hemodynamic fluctuations and their associated functional connections. Clinical studies have demonstrated that RSFC is altered in brain disorders such as stroke, Alzheimer's, autism, and epilepsy. However, conventional neuroimaging modalities cannot easily be applied to mice, the most widely used model species for human brain disease studies. For instance, functional magnetic resonance imaging (fMRI) of mice requires a very high magnetic field to obtain a sufficient signal-to-noise ratio and spatial resolution. Functional connectivity mapping with optical intrinsic signal imaging (fcOIS) is an alternative method. Due to the diffusion of light in tissue, the spatial resolution of fcOIS is limited, and experiments have been performed using an exposed skull preparation. In this study, we show for the first time, the use of photoacoustic computed tomography (PACT) to noninvasively image resting-state functional connectivity in the mouse brain, with a large field of view and a high spatial resolution. Bilateral correlations were observed in eight regions, as well as several subregions. These findings agreed well with the Paxinos mouse brain atlas. This study showed that PACT is a promising, non-invasive modality for small-animal functional brain imaging.", "doi": "10.1117/12.2036606", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89432O" }, { "id": "authors:q63tb-49h08", "collection": "authors", "collection_id": "q63tb-49h08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-101331425", "type": "book_section", "title": "Co-registered spectral photoacoustic tomography and ultrasonography of breast cancer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Jacobs", "given_name": "Eileen", "clpid": "Jacobs-E" }, { "family_name": "Holley", "given_name": "Susan", "clpid": "Holley-S" }, { "family_name": "Monsees", "given_name": "Barbara", "clpid": "Monsees-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Many breast cancer patients receive neoadjuvant treatment to reduce tumor size and enable breast conserving therapy. Most imaging methods used to monitor response to neoadjuvant chemotherapy or hormone therapy depend on overall gross tumor morphology and size measurements, which may not be sensitive or specific, despite tumor response on a cellular level. A more sensitive and specific method of detecting response to therapy might allow earlier adjustments in treatment, and thus result in better outcomes while avoiding unnecessary morbidity. We developed an imaging system that combines spectral photoacoustic tomography and ultrasonography to predict breast neoadjuvant therapeutic response based on blood volume and blood oxygenation contrast. The system consists of a tunable dye laser pumped by a Nd:YAG laser, a commercial ultrasound imaging system (Philips iU22), and a multichannel data acquisition system which displays co-registered photoacoustic and ultrasound images in real time. Early studies demonstrate functional imaging capabilities, such as oxygen saturation and total concentration of hemoglobin, in addition to ultrasonography of tumor morphology. Further study is needed to determine if the co-registered photoacoustic tomography and ultrasonography system may provide an accurate tool to assess treatment efficacy by monitoring tumor response in vivo.", "doi": "10.1117/12.2040591", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89434G" }, { "id": "authors:ypsmf-8pw92", "collection": "authors", "collection_id": "ypsmf-8pw92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-092401698", "type": "book_section", "title": "Mouse brain imaging using photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Lou", "given_name": "Yang", "clpid": "Lou-Yang" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) provides structural and functional information when used in small animal brain imaging. Acoustic distortion caused by bone structures largely limits the deep brain image quality. In our work, we present ex vivo PACT images of freshly excised mouse brain, intending that can serve as a gold standard for future PACT in vivo studies on small animal brain imaging. Our results show that structures such as the striatum, hippocampus, ventricles, and cerebellum can be clearly di erentiated. An artery feature called the Circle of Willis, located at the bottom of the brain, can also be seen. These results indicate that if acoustic distortion can be accurately accounted for, PACT should be able to image the entire mouse brain with rich structural information.", "doi": "10.1117/12.2039669", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894340" }, { "id": "authors:s82sp-mta62", "collection": "authors", "collection_id": "s82sp-mta62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-110305827", "type": "book_section", "title": "Broadening the detection view of high-frequency linear-array-based photoacoustic computed tomography by using planar acoustic reflectors", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) with a linear transducer array suffers from limited detection view. To increase the detection aperture, it is possible to circularly scan the linear transducer array around the object at the expense of imaging speed. Here we propose an alternative method to double or triple the detection view angle without sacrificing the imaging speed. By using a planar acoustic reflector which creates a virtual linear transducer array, the detection view angle is doubled. Similarly, by using two planar acoustic reflectors placed at 120 degrees to each other, we can form two virtual linear transducer arrays, and the detection view angle is tripled. This paper comparatively studies the two cases. We found that the planar acoustic reflectors greatly increase the detection aperture and thus significantly enhance the image quality of linear-array-base PACT systems.", "doi": "10.1117/12.2042725", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89430H" }, { "id": "authors:nee0j-yw382", "collection": "authors", "collection_id": "nee0j-yw382", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059859", "type": "book_section", "title": "Photothermal bleaching and recovery analysis in photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A novel method \u2013 photoacoustic recovery after photothermal bleaching (PRAP) \u2013 is proposed and implemented to study particle dynamics and medium properties at the micron scale via photoacoustic imaging. PRAP is an intuitive way to visualize as well as quantify dynamic processes in many kinds of media. We demonstrate PRAP first in a phantom study, and then in live cells. PRAP provides high signal-to-noise ratio imaging with minimal bleaching-induced artifacts during the recovery stage, ideal for monitoring the diffusive and kinetic phenomena inside a cell.", "doi": "10.1117/12.2040936", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89435Q" }, { "id": "authors:0ydez-g9z26", "collection": "authors", "collection_id": "0ydez-g9z26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-093051932", "type": "book_section", "title": "High-speed time-reversed ultrasonically encoded (TRUE) optical focusing inside dynamic scattering media at 793 nm", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Liu", "given_name": "Yan", "orcid": "0000-0002-5837-4908", "clpid": "Liu-Yan" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Ma", "given_name": "Cheng", "clpid": "Ma-Cheng" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Grabar", "given_name": "Alexander A.", "clpid": "Grabar-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Time-reversed ultrasonically encoded (TRUE) optical focusing is an emerging technique that focuses light deep into scattering media by phase-conjugating ultrasonically encoded diffuse light. In previous work, the speed of TRUE focusing was limited to no faster than 1 Hz by the response time of the photorefractive phase conjugate mirror, or the data acquisition and streaming speed of the digital camera; photorefractive-crystal-based TRUE focusing was also limited to the visible spectral range. These time-consuming schemes prevent this technique from being applied in vivo, since living biological tissue has a speckle decorrelation time on the order of a millisecond. In this work, using a Tedoped Sn_2P_2S_6 photorefractive crystal at a near-infrared wavelength of 793 nm, we achieved TRUE focusing inside dynamic scattering media having a speckle decorrelation time as short as 7.7 ms. As the achieved speed approaches the tissue decorrelation rate, this work is an important step forward toward in vivo applications of TRUE focusing in deep tissue imaging, photodynamic therapy, and optical manipulation.", "doi": "10.1117/12.2039815", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894339" }, { "id": "authors:kxcwp-zh492", "collection": "authors", "collection_id": "kxcwp-zh492", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059036", "type": "book_section", "title": "Photoacoustic correlation spectroscopy for calibration-free absolute quantification of particle concentration", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Currently, laser fluence calibration is typically required for quantitative measurement of particle concentration in photoacoustic microscopy. In this paper, we present another quantitative approach to measure absolute absorber concentrations by photoacoustic correlation spectroscopy. The proposed method is based on the fact that the Brownian motion induces particle count fluctuation in the detection volume. We first derived a theoretical model for photoacoustic signals and then applied our method to quantitative measurement of different concentrations of various particles. The experimental results agreed well with the predictions from the theoretical model, suggesting that our method can be used for absolute particle concentrations measurement.", "doi": "10.1117/12.2036635", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89431W" }, { "id": "authors:3tta7-2fr21", "collection": "authors", "collection_id": "3tta7-2fr21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-091734762", "type": "book_section", "title": "Localized fluorescence excitation in opaque media by time-reversed ultrasonically encoded (TRUE) optical focusing", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To focus light beyond one transport mean free path, time-reversed ultrasonically encoded (TRUE) optical focusing has previously been implemented by both analog and digital devices. By allowing wavefront recording with finer resolution and larger aperture, the analog scheme, which uses photorefractive materials as the phase-conjugate mirror, generates a more complete set of time-reversed optical modes than the digital scheme. Here, we report the direct visualization of localized fluorescence excitation inside a turbid medium by photorefractive time reversal. Further, we imaged fluorescent targets embedded in a turbid phantom whose thickness was four transport mean free paths.", "doi": "10.1117/12.2037947", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894358" }, { "id": "authors:jwxv4-a0084", "collection": "authors", "collection_id": "jwxv4-a0084", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-104942705", "type": "book_section", "title": "Low-rank matrix estimation-based spatio-temporal image reconstruction for dynamic photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Wang", "given_name": "Kun", "clpid": "Wang-Kun" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In order to monitor dynamic physiological events in near-real time, a variety of photoacoustic computed tomography (PACT) systems have been developed that can rapidly acquire data. Previously reported studies of dynamic PACT have employed conventional static methods to reconstruct a temporally ordered sequence of images on a frame-by-frame basis. Frame-by-frame image reconstruction (FBFIR) methods fail to exploit correlations between data frames and are known to be statistically and computationally suboptimal. In this study, a low-rank matrix estimation-based spatio-temporal image reconstruction (LRME-STIR) method is investigated for dynamic PACT applications. The LRME-STIR method is based on the observation that, in many PACT applications, the number of frames is much greater than the rank of the ideal noiseless data matrix. Using computer-simulated photoacoustic data, the performance of the LRME-STIR method is compared with that of conventional FBFIR method. The results demonstrate that LRME-STIR method is not only computationally more efficient but also produces more accurate dynamic PACT images than a conventional FBFIR method.", "doi": "10.1117/12.2041850", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89432I" }, { "id": "authors:vqhng-89c14", "collection": "authors", "collection_id": "vqhng-89c14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-093609284", "type": "book_section", "title": "Photoacoustic microscopy with enhanced resolution and imaging depth aided by optical clearing", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Both the spatial resolution and maximum penetration depth of optical-resolution photoacoustic microscopy (ORPAM) deteriorate sharply with depth due to strong light scattering in tissue. To reduce tissue scattering, we propose to use glycerol as an optical clearing agent in OR-PAM. Our results show that the imaging performance of OR-PAM can be greatly enhanced by optical clearing both in vitro and in vivo.", "doi": "10.1117/12.2036636", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89433A" }, { "id": "authors:0cq1g-qjs88", "collection": "authors", "collection_id": "0cq1g-qjs88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-073236986", "type": "book_section", "title": "Functional connectivity in the mouse brain imaged by B-mode photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Nasiriavanaki", "given_name": "Mohammadreza", "clpid": "Nasiriavanaki-M" }, { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The increasing use of mouse models for human brain disease studies, coupled with the fact that existing functional imaging modalities cannot be easily applied to mice, presents an emerging need for a new functional imaging modality. Utilizing acoustic-resolution photoacoustic microscopy (AR-PAM), we imaged spontaneous cerebral hemodynamic fluctuations and their associated functional connections in the mouse brain. The images were acquired noninvasively in B-scan mode with a fast frame rate, a large field of view, and a high spatial resolution. At a location relative to the bregma 0, correlations were investigated inter-hemispherically between bilaterally homologous regions, as well as intra-hemispherically within the same functional regions. The functional connectivity in different functional regions was studied. The locations of these regions agreed well with the Paxinos mouse brain atlas. The functional connectivity map obtained in this study can then be used in the investigation of brain disorders such as stroke, Alzheimer's, schizophrenia, multiple sclerosis, autism, and epilepsy. Our experiments show that photoacoustic microscopy is capable to detect connectivities between different functional regions in B-scan mode, promising a powerful functional imaging modality for future brain research.", "doi": "10.1117/12.2036638", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894364" }, { "id": "authors:krm2w-4qp30", "collection": "authors", "collection_id": "krm2w-4qp30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059460", "type": "book_section", "title": "Digital reflection-mode time-reversed ultrasonically encoded (TRUE) optical focusing", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Tay", "given_name": "Jian Wei", "clpid": "Tay-Jian-Wei" }, { "family_name": "Yang", "given_name": "Qiang", "clpid": "Yang-Qiang" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To achieve localized light delivery beyond turbid layers, TRUE optical focusing has been previously implemented by both analog and digital devices. The digital scheme offers a higher energy gain than the analog version. In many biological applications, the reflection-mode configuration, which uses backscattered light from the sample, is more suitable than the transmission-mode configuration. Although reflection-mode analog TRUE focusing has been demonstrated, its digital implementation has not been explored. Here, we report a reflection-mode digital TRUE focusing to concentrate light through a turbid layer. Further, by simply moving the ultrasound focus, we show the system's dynamic focusing capability.", "doi": "10.1117/12.2037952", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89431B" }, { "id": "authors:5brar-k8565", "collection": "authors", "collection_id": "5brar-k8565", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160622-092424136", "type": "book_section", "title": "A Dual-Modality Photoacoustic and Ultrasound Imaging System for Noninvasive Sentinel Lymph Node Detection: Preliminary Clinical Results", "author": [ { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Krumholz", "given_name": "Arie", "clpid": "Krumholz-A" }, { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Appleton", "given_name": "Catherine", "clpid": "Appleton-C" }, { "family_name": "Margenthaler", "given_name": "Julie", "clpid": "Margenthaler-J" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Sentinel lymph node biopsy (SLNB) has emerged as an accurate, less invasive alternative to\naxillary lymph node dissection, and it has rapidly become the standard of care for patients with\nclinically node-negative breast cancer. The sentinel lymph node (SLN) hypothesis states that the\npathological status of the axilla can be accurately predicted by determining the status of the first\n(i.e., sentinel) lymph nodes that drain from the primary tumor. Physicians use radio-labeled\nsulfur colloid and/or methylene blue dye to identify the SLN, which is most likely to contain\nmetastatic cancer cells. However, the surgical procedure causes morbidity and associated\nexpenses. To overcome these limitations, we developed a dual-modality photoacoustic and\nultrasound imaging system to noninvasively detect SLNs based on the accumulation of\nmethylene blue dye. Ultimately, we aim to guide percutaneous needle biopsies and provide a\nminimally invasive method for axillary staging of breast cancer. The system consists of a tunable\ndye laser pumped by a Nd:YAG laser, a commercial ultrasound imaging system (Philips iU22),\nand a multichannel data acquisition system which displays co-registered photoacoustic and\nultrasound images in real-time. Our clinical results demonstrate that real-time photoacoustic\nimaging can provide sensitive and specific detection of methylene blue dye in vivo. While\npreliminary studies have shown that in vivo detection of SLNs by using co-registered\nphotoacoustic and ultrasound imaging is feasible, further investigation is needed to demonstrate\nrobust SLN detection.", "doi": "10.1117/12.2040475", "publisher": "Society of Photo-Optical Instrumentation Engineers", "publication_date": "2014-03-03" }, { "id": "authors:629pf-8sg23", "collection": "authors", "collection_id": "629pf-8sg23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-100407993", "type": "book_section", "title": "Intracellular temperature mapping with fluorescence-assisted photoacoustic thermometry", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Measuring intracellular temperature is critical to understanding many cellular functions but still remains challenging. Here we present a technique \u2013 fluorescence-assisted photoacoustic thermometry (FAPT) \u2013 for intracellular temperature mapping applications. To demonstrate FAPT, we monitored the intracellular temperature distribution of HeLa cells with sub-degree (0.7 \u00b0C) temperature resolution and sub-micron (0.23 \u03bcm) spatial resolution at a sampling rate of 1 kHz. Compared to traditional fluorescence-based methods, FAPT features the unique capability of transforming a regular fluorescence probe into a concentration- and excitation-independent temperature sensor, bringing a large collection of commercially available generic fluorescent probes into the realm of intracellular temperature sensing.", "doi": "10.1117/12.2038569", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894309" }, { "id": "authors:j7zy9-22j46", "collection": "authors", "collection_id": "j7zy9-22j46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-084804131", "type": "book_section", "title": "Simultaneous reconstruction of absorbed optical energy density and speed of sound distributions in photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Huang", "given_name": "Chao", "clpid": "Huang-Chao" }, { "family_name": "Wang", "given_name": "Kun", "clpid": "Wang-Kun" }, { "family_name": "Schoonover", "given_name": "Robert W.", "clpid": "Schoonover-R-W" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "An important and interesting question in photoacoustic computed tomography (PACT) is whether the absorbed optical energy density distribution, A(r), and the speed of sound distribution, c(r), can both be accurately determined from the measured photoacoustic data alone. However, in many cases c(r) is unknown or cannot be accurately estimated. Therefore, it would be practically beneficial if A(r) and c(r) can be jointly reconstructed from the measurements. In this work, we propose a reconstruction approach to the joint reconstruction of both properties in PACT.", "doi": "10.1117/12.2041825", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894360" }, { "id": "authors:0pb76-cp433", "collection": "authors", "collection_id": "0pb76-cp433", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059355", "type": "book_section", "title": "Noninvasive measurement of internal jugular venous oxygen saturation by photoacoustic imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Reddy", "given_name": "Kavya", "clpid": "Reddy-K" }, { "family_name": "Sharma", "given_name": "Anshuman", "clpid": "Sharma-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The metabolic rate and oxygen consumption of the brain is reflected in jugular venous oxygen saturation. In many clinical conditions, such as head trauma, stroke, and low cardiac output states, the brain is at risk for hypoxic-ischemic injury. The current gold standard for monitoring brain oxygenation is invasive and requires jugular vein catheterization under fluoroscopic guidance; and therefore it is rarely used. Photo-acoustic tomography in combination with ultrasound can be used to estimate oxygen saturation of the internal jugular vein in real-time. This noninvasive method will enable earlier detection and prevention of impending hypoxic brain injury. A wavelength-tunable dye laser pumped by a Nd:YAG laser delivers light through an optical fiber bundle, and a modified commercial ultrasound imaging system (Philips iU22) detects both the pulse-echo ultrasound (US) and photoacoustic (PA) signals. A custom-built multichannel data acquisition system renders co-registered ultrasound and photoacoustic images at 5 frames per second. After the jugular vein was localized in healthy volunteers, dualwavelength PA images were used to calculate the blood hemoglobin oxygen saturation from the internal jugular vein in vivo. The preliminary results raise confidence that this emerging technology can be used clinically as an accurate, noninvasive indicator of cerebral oxygenation.", "doi": "10.1117/12.2040589", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89431M" }, { "id": "authors:x68dy-9sc38", "collection": "authors", "collection_id": "x68dy-9sc38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-164454399", "type": "book_section", "title": "Cross-optical-beam nonlinear photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhu", "given_name": "Liren", "orcid": "0000-0002-6338-9338", "clpid": "Zhu-Liren" }, { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Ma", "given_name": "Teng", "clpid": "Ma-Teng" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a photoacoustic microscopy (PAM) technique with an optical sectioning capability. By combining crossoptical- beam illumination with nonlinear PAM, an axial resolution of 8.7 \u03bcm was measured, demonstrating a fourfold improvement over the acoustically determined value. Compared to methods relying on high-frequency ultrasound transducers to improve the axial resolution, our approach offers a greater working distance and a higher signal-to-noise ratio.", "doi": "10.1117/12.2037926", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89433H" }, { "id": "authors:hb0jh-nwr16", "collection": "authors", "collection_id": "hb0jh-nwr16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-094150179", "type": "book_section", "title": "Improving the axial resolution in time-reversed ultrasonically encoded (TRUE) optical focusing with dual ultrasonic waves", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Yang", "given_name": "Qiang", "clpid": "Yang-Qiang" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Sang", "given_name": "Xinzhu", "clpid": "Sang-Xinzhu" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Focusing light inside highly scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging, manipulation, and therapy. This challenge can be overcome by time reversing ultrasonically encoded (TRUE) diffuse light to the ultrasonic focus inside a turbid medium. In TRUE optical focusing, a photorefractive crystal or polymer is used as the phase conjugate mirror for optical time reversal. Accordingly, a relatively long ultrasound burst, whose duration matches the response time of the photorefractive material, is used to encode the diffuse light. With this long ultrasound burst, the resolution of the TRUE focus along the acoustic axis is poor. In this work, we used two transducers, emitting two intersecting ultrasound beams at 3.4 MHz and 3.6 MHz respectively, to modulate the diffuse light within their intersection volume at the beat frequency. We show that light encoded at the beat frequency can be time-reversed and converge to the intersection volume. Experimentally, TRUE focusing with an acoustic axial resolution of ~1.1 mm was demonstrated inside turbid media, agreeing with the theoretical estimation.", "doi": "10.1117/12.2038797", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894338" }, { "id": "authors:7jjdn-fzd27", "collection": "authors", "collection_id": "7jjdn-fzd27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-095129423", "type": "book_section", "title": "Optical focusing in scattering media with photoacoustic wavefront shaping (PAWS)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Tay", "given_name": "Jian Wei", "clpid": "Tay-Jian-Wei" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Controllable light delivery to the region of interest is essential to biomedical optical imaging methods like photoacoustic microscopy. It is, however, challenging beyond superficial depths in biological tissue (~1 mm beneath human skin) due to the strong scattering of light that scrambles the photon propagation paths. Recently, optical wavefront shaping has been proposed to modulate the incident light wavefront to compensate for the scattering-induced phase distortions, and consequentially, convey light optimally to a desired location behind or inside turbid media. To reach an optimum wavefront, a searching algorithm is usually required to optimize a feedback signal. In this work, we present our latest explorations, which use photoacoustic signals as the feedback to remotely and non-invasively guide the wavefront shaping process. Our method does not require direct optical access to the target region or the invasive embedding of fluorescence probes inside turbid media. Experimentally, we have demonstrated that diffuse light can be converged to the ultrasound focus by maximizing the amplitude of photoacoustic emissions from the intended absorbing site. Moreover, we show that wavefront-shaped light focusing can enhance existing optical imaging modalities like photoacoustic microscopy, in regard to signal-to-noise ratio, imaging depth, and potentially, resolution.", "doi": "10.1117/12.2036510", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894318" }, { "id": "authors:tfy6g-rye96", "collection": "authors", "collection_id": "tfy6g-rye96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-161800611", "type": "book_section", "title": "Investigation of effective system designs for transcranial photoacoustic tomography of the brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Mitsuhashi", "given_name": "Kenji", "clpid": "Mitsuhashi-Kenji" }, { "family_name": "Schoonover", "given_name": "Robert W.", "clpid": "Schoonover-R-W" }, { "family_name": "Huang", "given_name": "Chao", "clpid": "Huang-Chao" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) holds great promise for transcranial brain imaging. However, the strong reflection, scattering and attenuation of acoustic waves in the skull present significant challenges to developing this method. We report on a systematic computer-simulation study of transcranial brain imaging using PACT. The goal of this study was to identify an effective imaging system design that can be translated for clinical use. The propagation of photoacoustic waves through a model skull was studied by use of an elastic finite-difference time-domain (FDTD) method. The acoustic radiation pattern from a photoacoustic source just beneath the skull was observed with a ring transducer array that was level with the source. The observed radiation pattern was found to contain stronger contributions from waves that were converted to shear waves in skull than longitudinal waves that did not undergo mode conversion. Images reconstructed from the pressure data that contain shear wave components possess better resolution than images reconstructed from the data that only contain the longitudinal wave signals. These observations revealed that the detection system should be designed to capture photoacoustic signals that travel through the skull in the form of shear waves as well as in the form of longitudinal waves. A preliminary investigation on the effect of the presence of absorption in the skull is also reported. This study provides an insight into the wave phenomena in transcranial PACT imaging, as well as a concrete detection design strategy that mitigates the degraded resolution of reconstructed images.", "doi": "10.1117/12.2041998", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894369" }, { "id": "authors:gbk70-szm05", "collection": "authors", "collection_id": "gbk70-szm05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160809-080427619", "type": "book_section", "title": "Photothermal bleaching in time-lapse photoacoustic microscopy", "author": [ { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We studied the phenomenon of photothermal bleaching \u2014 a gradual reduction of contrast agent particles during repeated scans in photoacoustic microscopy. The dependence of the photothermal bleaching rate on the excitation pulse energy was determined while the laser focal diameter was held constant. Our results showed that, the dependence of the photothermal bleaching rate on the excitation pulse energy differed before and after the absorbers were raised to their melting point by the deposited laser energy. Based on this finding, we suggested an optimal excitation pulse energy, which balances the photothermal bleaching rate and signal amplitude, for time-lapse imaging applications.", "doi": "10.1117/12.2038564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "publication_date": "2014-03-03" }, { "id": "authors:g58a0-1zy69", "collection": "authors", "collection_id": "g58a0-1zy69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-094818431", "type": "book_section", "title": "Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A decade of research has pushed photoacoustic computed tomography to the forefront of molecular-level imaging, notes SPIE Fellow Lihong Wang (Washington University, St. Louis) in his plenary talk, \"Photoacoustic Tomography: Ultrasonically Beating Optical Diffusion and Diffraction.\" Modern optical microscopy has resolution and diffraction limitations. But noninvasive functional photoacoustic computed tomography has overcome this limit, offering deep penetration with optical contrast and ultrasonic resolution of 1 cm depth or more -- up to 7 cm of penetration in some cases, such as evaluating sentinel lymph nodes for breast cancer staging. This opens up applications in whole body imaging, brain function, oxygen saturation, label-free cell analysis, and noninvasive cancer biopsies.", "doi": "10.1117/12.2064189", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894334" }, { "id": "authors:g8xeb-azw35", "collection": "authors", "collection_id": "g8xeb-azw35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180911-164454484", "type": "book_section", "title": "Focusing light in scattering media by ultrasonically encoded wavefront shaping (SEWS)", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Tay", "given_name": "Jian Wei", "clpid": "Tay-Jian-Wei" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Wavefront distortion in scattering media can be compensated for using optical wavefront shaping. In this technique, a spatial light modulator (SLM) is used to apply a spatially distributed phase shift to the optical field. A genetic optimization algorithm was used to obtain the SLM pattern which best focuses light within the medium. The target volume is defined by using a focused ultrasound beam to encode light travelling within the acoustic focus. The ultrasonically-encoded light is measured and used as feedback to the algorithm, which then searches for the pattern which maximizes the encoded light intensity. We call this technique ultrasonically-encoded wavefront shaping (SEWS). Using SEWS, we focused light into a scattering medium consisting of ground glass diffuser and a gelatin phantom. The optical intensity at the target was increased by 11 times over the original intensity. These results were validated using fluorescent imaging at the ultrasonic focus.", "doi": "10.1117/12.2037037", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89434P" }, { "id": "authors:cna5y-n6s26", "collection": "authors", "collection_id": "cna5y-n6s26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059240", "type": "book_section", "title": "Combined optical and mechanical scanning in optical-resolution photoacoustic microscopy", "author": [ { "family_name": "Li", "given_name": "Lei", "orcid": "0000-0001-6164-2646", "clpid": "Li-Lei" }, { "family_name": "Yeh", "given_name": "Chenghung", "clpid": "Yeh-Chenghung" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Soetikno", "given_name": "Brian T.", "clpid": "Soetikno-B-T" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Combined optical and mechanical scanning (COMS) in optical-resolution photoacoustic microscopy (OR-PAM) has provided five scanning modes with fast imaging speed and wide field of view (FOV). With two-dimensional (2D) galvanometer-based optical scanning, we have achieved a 2 KHz B-scan rate and 50 Hz volumetric-scan rate, which enables real-time tracking of cell activities in vivo. With optical-mechanical hybrid 2D scanning, we are able to image a wide FOV (10\u00d78 mm2) within 150 seconds, which is 20 times faster than the conventional mechanical scan in our second-generation OR-PAM. With three-dimensional mechanical-based contour scanning, we can maintain the optimal signal-to-noise ratio and spatial resolution of OR-PAM while imaging objects with uneven surfaces, which is ideal for fast and quantitative studies of tumors and the brain.", "doi": "10.1117/12.2038693", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "publication_date": "2014-03-03" }, { "id": "authors:csnxx-65n02", "collection": "authors", "collection_id": "csnxx-65n02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-103856411", "type": "book_section", "title": "Acoustic-speed correction of photoacoustic tomography by ultrasonic computed tomography based on optical excitation of elements of a full-ring transducer array", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Huang", "given_name": "Chao", "clpid": "Huang-Chao" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) is a hybrid technique that combines optical excitation and ultrasonic detection to provide high resolution images in deep tissues. In the image reconstruction, a constant speed of sound (SOS) is normally assumed. This assumption, however, is often not strictly satisfied in deep tissue imaging, due to acoustic heterogeneities within the object and between the object and coupling medium. If these heterogeneities are not accounted for, they will cause distortions and artifacts in the reconstructed images. In this paper, we incorporated ultrasonic computed tomography (USCT), which measures the SOS distribution within the object, into our full-ring array PACT system. Without the need for ultrasonic transmitting electronics, USCT was performed using the same laser beam as for PACT measurement. By scanning the laser beam on the array surface, we can sequentially fire different elements. As a first demonstration of the system, we studied the effect of acoustic heterogeneities on photoacoustic vascular imaging. We verified that constant SOS is a reasonable approximation when the SOS variation is small. When the variation is large, distortion will be observed in the periphery of the object, especially in the tangential direction.", "doi": "10.1117/12.2036615", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89432G" }, { "id": "authors:9g7ay-vjy18", "collection": "authors", "collection_id": "9g7ay-vjy18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-105618810", "type": "book_section", "title": "Photoacoustic molecular imaging of angiogenesis using theranostic \u03b1_\u03bd\u03b2_3-targeted copper nanoparticles incorporating a sn-2 lipase-labile fumagillin prodrug", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Yang", "given_name": "Xiaoxia", "clpid": "Yang-Xiaoxia" }, { "family_name": "Senpan", "given_name": "Angana", "clpid": "Senpan-A" }, { "family_name": "Allen", "given_name": "John S.", "clpid": "Allen-J-S" }, { "family_name": "Pan", "given_name": "Dipanjan", "clpid": "Pan-Dipanjan" }, { "family_name": "Lanza", "given_name": "Gregory M.", "clpid": "Lanza-G-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic (PA) tomography imaging is an emerging, versatile, and noninvasive imaging modality, which combines the advantages of both optical imaging and ultrasound imaging. It opens up opportunities for noninvasive imaging of angiogenesis, a feature of skin pathologies including cancers and psoriasis. In this study, high-density copper oleate encapsulated within a phospholipid surfactant (CuNPs) generated a soft nanoparticle with PA contrast comparable to gold. Within the near-infrared window, the copper nanoparticles can provide a signal more than 7 times higher that of blood. \u0391_\u03bd\u03b2_3-targeted of CuNPs in a Matrigel mouse model demonstrated prominent PA contrast enhancement of the neovasculature compared to mice given nontargeted or competitively inhibited CuNPs. Incorporation of a sn-2 lipase-labile fumagillin prodrug into the CuNPs produced marked antiangiogenesis in the same model, demonstrating the theranostic potential of a PA agent for the first time in vivo. With a PA signal comparable to gold-based nanoparticles yet a lower cost and demonstrated drug delivery potential, \u03b1_\u03bd\u03b2_3-targeted CuNPs hold great promise for the management of skin pathologies with neovascular features.", "doi": "10.1117/12.2041120", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89435I" }, { "id": "authors:aydrv-xqw11", "collection": "authors", "collection_id": "aydrv-xqw11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180912-095829705", "type": "book_section", "title": "Photoacoustic microscopy with an enhanced axial resolution of 5.8 \u03bcm", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The axial resolution of photoacoustic microscopy (PAM) can be enhanced by reducing the speed of sound within the imaging region of interest. This principle was demonstrated on a previously-reported PAM system, which utilized a 125 MHz ultrasonic transducer for signal detection and the Wiener deconvolution for signal processing. With sound slowed by silicone oil immersion, we have achieved a finest axial resolution of 5.8 \u03bcm for PAM, as validated by phantom experiments. The axial resolution was also enhanced in vivo when mouse ears injected with silicone oil were imaged. After injection of silicone oil, the blood vessels were resolved more clearly. When tissue-compatible low-speed liquids become available, this approach may find applications in PAM as well as in other imaging modalities, such as photoacoustic computed tomography and ultrasound imaging.", "doi": "10.1117/12.2036832", "isbn": "9780819498564", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 894316" }, { "id": "authors:rkg55-rr562", "collection": "authors", "collection_id": "rkg55-rr562", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-151059543", "type": "book_section", "title": "Photoacoustic Doppler axial flow measurement of homogenous media using structured illumination", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2014", "author": [ { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We propose time and frequency domain methods for homogenous flow measurement based on the photoacoustic Doppler effect. Excited by spatially modulated laser pulses, the flowing medium induces a Doppler frequency shift in the received photoacoustic signals. The frequency shift is proportional to the component of the flow speed projected onto the acoustic beam axis. These methods do not rely on particle heterogeneity in the medium. A red-ink phantom flowing in a tube immersed in water was used to validate the methods in both frequency and time domains.", "doi": "10.1117/12.2038356", "isbn": "9780819498564", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2014-03-03", "pages": "Art. No. 89431U" }, { "id": "authors:7mzvt-1qk33", "collection": "authors", "collection_id": "7mzvt-1qk33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421069", "type": "book_section", "title": "Photoacoustic endoscopic imaging study of melanoma tumor growth in a rat colorectum in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Zhang", "given_name": "Yu", "orcid": "0000-0001-8938-1927", "clpid": "Zhang-Yu" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We performed a photoacoustic endoscopic imaging study of melanoma tumor growth in a nude rat in vivo. After inducing the tumor at the colorectal wall of the animal, we monitored the tumor development in situ by using a photoacoustic endoscopic system. This paper introduces our experimental method for tumor inoculation and presents imaging results showing the morphological changes of the blood vasculature near the tumor region according to the tumor progress. Our study could provide insights for future studies on tumor development in small animals.", "doi": "10.1117/12.2005470", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85810D" }, { "id": "authors:gk252-ykd06", "collection": "authors", "collection_id": "gk252-ykd06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421376", "type": "book_section", "title": "A parabolic mirror-based proximally actuated photoacoustic endoscope", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have developed a new photoacoustic endoscopic probe specifically designed for human urogenital imaging. The endoscopic probe uses a parabolic mirror-based mechanical scanning mechanism, providing an angular field of view of 270\u00b0. And it has a rigid, dome shaped end section for smooth cavity introduction. Here we introduce the new endoscope's design and imaging principle, and present experimental results validating its in vivo imaging ability.", "doi": "10.1117/12.2005494", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858148" }, { "id": "authors:4nerv-61v52", "collection": "authors", "collection_id": "4nerv-61v52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-101020076", "type": "book_section", "title": "Multifocal optical-resolution photoacoustic microscopy in reflection mode", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Li", "given_name": "Guo", "clpid": "Li-Guo" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Compared with single-focus optical-resolution photoacoustic microscopy (OR-PAM), multifocal OR-PAM utilizes both multifocal optical illumination and an ultrasonic array transducer, significantly increasing the imaging speed. Here we present a reflection-mode multifocal OR-PAM system based on a microlens array that provides multiple foci and an ultrasonic array transducer that receives the excited photoacoustic waves from all foci simultaneously. By using a customized microprism to reflect the incident laser beam to the microlens array, we align the multiple optical foci confocally with the focal zone of the ultrasonic array transducer. Experiments show our reflection-mode multifocal ORPAM system is capable of imaging microvessels in vivo, and it can image a 9 mm x 5 mm x 2.5 mm volume at 16 \u03bcm lateral resolution in ~4 min, limited by the signal multiplexing ratio and laser pulse repetition rate.", "doi": "10.1117/12.2005673", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858126" }, { "id": "authors:dqyf4-jrp74", "collection": "authors", "collection_id": "dqyf4-jrp74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549342", "type": "book_section", "title": "Towards single molecule detection using photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Winkler", "given_name": "Amy M.", "clpid": "Winkler-A-M" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Recently, a number of optical imaging modalities have achieved single molecule sensitivity, including photothermal imaging, stimulated emission microscopy, ground state depletion microscopy, and transmission microscopy. These optical techniques are based on optical absorption contrast, extending single-molecule detection to non-fluorescent chromophores. Photoacoustics is a hybrid technique that utilizes optical excitation and ultrasonic detection, allowing it to scale both the optical and acoustic regimes with 100% sensitivity to optical absorption. However, the sensitivity of photoacoustics is limited by thermal noise, inherent in the medium itself in the form of acoustic black body radiation. In this paper, we investigate the molecular sensitivity of photoacoustics in the context of the thermal noise limit. We show that single molecule sensitivity is achievable theoretically at room temperature for molecules with sufficiently fast relaxation times. Hurdles to achieve single molecule sensitivity in practice include development of detection schemes that work at short working distance, <100 microns, high frequency, <100 MHz, and low loss, <10 dB.", "doi": "10.1117/12.2004265", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85811A" }, { "id": "authors:w84ze-eb717", "collection": "authors", "collection_id": "w84ze-eb717", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421647", "type": "book_section", "title": "Video-rate photoacoustic microscopy of micro-vasculatures", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Garcia-Uribe", "given_name": "Alejandro", "clpid": "Garcia-Uribe-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report the development of photoacoustic microscopy capable of video-rate high-resolution in-vivo imaging in deep tissue. A lightweight photoacoustic probe is made of a single-element broadband ultrasound transducer, a compact photoacoustic beam combiner, and a bright-field light delivery system. Focused broadband ultrasound detection provides a 44-\u03bcm lateral resolution and a 28-\u03bcm axial resolution. A multimode optical fiber is used to deliver laser pulses. The bright-field light delivery system can effectively improve the illumination efficiency. The photoacoustic probe weighs less than 40 grams and is mounted on a voice-coil scanner to acquire 40 cross-sectional images per second over several-mm range. The fast speed can effectively improve imaging throughput, reduce motion artifacts, and enable the visualization of highly dynamic biomedical processes. High-resolution micro-vascular imaging is successfully demonstrated.", "doi": "10.1117/12.2004714", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85811T" }, { "id": "authors:n2x2j-zw589", "collection": "authors", "collection_id": "n2x2j-zw589", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421466", "type": "book_section", "title": "Image reconstruction in photoacoustic tomography with heterogeneous media using an iterative method", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Huang", "given_name": "Chao", "clpid": "Huang-Chao" }, { "family_name": "Wang", "given_name": "Kun", "clpid": "Wang-Kun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "There remains an urgent need to develop effective photoacoustic computed tomography (PACT) image recon- struction methods for use with acoustically inhomogeneous media. Transcranial PACT brain imaging is an im- portant example of an emerging imaging application that would benefit greatly from this. Existing approaches to PACT image reconstruction in acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or make impractical assumptions regarding the measurement geometry. In this work, we develop and investigate a full-wave approach to iterative image reconstruction in PACT for media possessing inhomogeneous speed-of-sound and mass density distributions. A key contribution of the work is the formulation of a procedure to implement a matched discrete forward and backprojection operator pair, which facilitates the application of a wide range of modern iterative image reconstruction algorithms. This presents the opportunity to employ application-specific regularization methods to mitigate image artifacts due to mea- surement data incompleteness and noise. Our results establish that the proposed image reconstruction method can effectively compensate for acoustic aberration and reduces artifacts in the reconstructed image.", "doi": "10.1117/12.2007072", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858106" }, { "id": "authors:sj911-thd41", "collection": "authors", "collection_id": "sj911-thd41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549257", "type": "book_section", "title": "F\u00f6rster resonance energy transfer photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "F\u00f6rster resonance energy transfer (FRET) provides fluorescence signals sensitive to intra- and inter-molecular distances in the 1-10 nm range. Widely applied in the optical imaging environment, FRET enables visualization of physicochemical processes in molecular interactions and conformation changes. We reported photoacoustic imaging of FRET, based on non-radiative decay that produces heat and subsequent acoustic waves. The experimental results show that photoacoustic imaging offers better penetration into scattering biological tissue. Through its ability to three-dimensionally image tissue with scalable resolution, photoacoustic microscopy provides a beneficial biomedical tool to broaden the in vivo application of the FRET technique.", "doi": "10.1117/12.2004150", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. no. 85812E" }, { "id": "authors:194d7-7vp78", "collection": "authors", "collection_id": "194d7-7vp78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421286", "type": "book_section", "title": "Photoacoustic microscopy with 7.6-\u03bcm axial resolution", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The axial resolution of photoacoustic microscopy (PAM) is much lower than its lateral resolution, which resolves down to the submicron level. Here we achieved so far the highest axial resolution of 7.6 \u03bcm by using a commercial 125 MHz ultrasonic transducer for signal detection, followed by the Wiener deconvolution for signal processing. The axial resolution was validated by imaging two layers of red ink in a wedge shape. Melanoma cells were imaged ex vivo with high axial resolution. Compared with a PAM system with a 50 MHz ultrasonic transducer, our high-axial-resolution PAM system resolved the blood vessels in mouse ears in vivo much more clearly in the depth direction.", "doi": "10.1117/12.2003248", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85812W" }, { "id": "authors:z38mv-93h76", "collection": "authors", "collection_id": "z38mv-93h76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421183", "type": "book_section", "title": "Novel micromachined silicon acoustic delay line systems for real-time photoacoustic tomography applications", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Chang", "given_name": "C.-C.", "clpid": "Chang-Cheng-Chung" }, { "family_name": "Cho", "given_name": "Y.", "clpid": "Cho-Y" }, { "family_name": "Wang", "given_name": "L. V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zou", "given_name": "J.", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In current photoacoustic tomography (PAT) systems, ultrasound transducer arrays and multi-channel data acquisition (DAQ) electronics are used to receive the PA signals. To achieve real-time PA imaging, massive 1D or even 2D transducer arrays and large number of DAQ channels are necessary. As a result, the ultrasound receiver becomes very complex, bulky and also costly. In this paper, we report the development of novel micromachined silicon acoustic delay line systems, which are expected to provide a new approach to address the above issue. First, fundamental building block structures of the acoustic delay line systems were designed and fabricated. Their acoustic properties were characterized with ultrasound and photoacoustic measurements. Second, two different acoustic delay line systems (parallel and serial) were designed and fabricated using advanced micromachining processes to ensure compact size, high accuracy, and good repeatability. The transmission of multiple acoustic signals in the acoustic delay line systems were studied with ultrasound experiment. Experimental results show that the silicon acoustic delay line systems can guide multiple channels of acoustic signals with low loss and distortion. With the addition of a set of suitable time delays, the time-delay acoustic signals arrived at a single-element transducer at different times and were unambiguously received and processed by the following DAQ electronics. Therefore, the micromachined silicon acoustic delay line systems could be used to combine multiple signal channels into a single one (without the involvement of electronic multiplexing), thereby reducing the complexity and cost of the ultrasound receiver for real-time PAT application.", "doi": "10.1117/12.2004573", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85813B" }, { "id": "authors:2cy14-0g437", "collection": "authors", "collection_id": "2cy14-0g437", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549538", "type": "book_section", "title": "Parallel acoustic delay lines for photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Yapici", "given_name": "Murat Kaya", "clpid": "Yapici-M-K" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Chang", "given_name": "Cheng-Chung", "clpid": "Chang-Cheng-Chung" }, { "family_name": "Jeon", "given_name": "Mansik", "clpid": "Jeon-Mansik" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Achieving real-time photoacoustic (PA) tomography typically requires massive ultrasound transducer arrays and data acquisition (DAQ) electronics to receive PA waves simultaneously. In this paper, we report the first demonstration of a photoacoustic tomography (PAT) system using optical fiber-based parallel acoustic delay lines (PADLs). By employing PADLs to introduce specific time delays, the PA signals (on the order of a few micro seconds) can be forced to arrive at the ultrasonic transducers at different times. As a result, time-delayed PA signals in multiple channels can be ultimately received and processed in a serial manner with a single-element transducer, followed by single\u2010channel DAQ electronics. Our results show that an optically absorbing target in an optically scattering medium can be photoacoustically imaged using the newly developed PADL-based PAT system. Potentially, this approach could be adopted to significantly reduce the complexity and cost of ultrasonic array receiver systems.", "doi": "10.1117/12.2003289", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85811C" }, { "id": "authors:q7c8g-dhw44", "collection": "authors", "collection_id": "q7c8g-dhw44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-154406554", "type": "book_section", "title": "Quantitative imaging of bilirubin by photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Zhou", "given_name": "Yong", "clpid": "Zhou-Yong" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Yao", "given_name": "Da-Kang", "clpid": "Yao-Da-Kang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Noninvasive detection of both bilirubin concentration and its distribution is important for disease diagnosis. Here we implemented photoacoustic microscopy (PAM) to detect bilirubin distribution. We first demonstrate that our PAM system can measure the absorption spectra of bilirubin and blood. We also image bilirubin distributions in tissue-mimicking samples, both without and with blood mixed. Our results show that PAM has the potential to quantitatively image bilirubin in vivo for clinical applications.", "doi": "10.1117/12.2004394", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85813A" }, { "id": "authors:j16yc-tks58", "collection": "authors", "collection_id": "j16yc-tks58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549439", "type": "book_section", "title": "Single-cell photoacoustic thermometry", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Liu", "given_name": "Yan", "orcid": "0000-0002-5837-4908", "clpid": "Liu-Yan" }, { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A novel photoacoustic thermometric method is presented for simultaneously imaging cells and sensing their temperature. With 3 seconds per frame imaging speed, a temperature resolution of 0.2 \u00b0C was achieved in a photo-thermal cell heating experiment. Compared to other approaches, the photoacoustic thermometric method has the advantage of not requiring custom-developed temperature-sensitive biosensors. This feature should facilitate the conversion of single-cell thermometry into a routine lab tool and make it accessible to a much broader biological research community.", "doi": "10.1117/12.2004063", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858118" }, { "id": "authors:w7mc4-xen67", "collection": "authors", "collection_id": "w7mc4-xen67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094548927", "type": "book_section", "title": "Photoacoustic microscopy of neovascularization in three-dimensional porous scaffolds in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Zhang", "given_name": "Yu", "orcid": "0000-0001-8938-1927", "clpid": "Zhang-Yu" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Choi", "given_name": "Sung-Wook", "clpid": "Choi-Sung-Wook" }, { "family_name": "MacEwan", "given_name": "Matthew R.", "clpid": "MacEwan-M-R" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "It is a challenge to non-invasively visualize in vivo the neovascularization in a three-dimensional (3D) scaffold with high spatial resolution and deep penetration depth. Here we used photoacoustic microscopy (PAM) to chronically monitor neovascularization in an inverse opal scaffold implanted in a mouse model for up to six weeks. The neovasculature was observed to develop gradually in the same mouse. These blood vessels not only grew on top of the implanted scaffold but also penetrated into the scaffold. The PAM system offered a lateral resolution of ~45 \u03bcm and a penetration depth of ~3 mm into the scaffold/tissue construct. By using the 3D PAM data, we further quantified the vessel area as a function of time.", "doi": "10.1117/12.2005236", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858128" }, { "id": "authors:aa56d-4j402", "collection": "authors", "collection_id": "aa56d-4j402", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421730", "type": "book_section", "title": "High-efficiency time-reversed ultrasonically encoded optical focusing using a large-area photorefractive polymer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Time-reversed ultrasonically encoded (TRUE) optical focusing focuses light beyond one transport mean free path by phase-conjugating the ultrasonically tagged light. However, in previous works, only a small portion of the tagged light was phase-conjugated by using a photorefractive Bi_(12)SiO_(20) crystal, due to its small active area (1x1 cm^2). In this work, we report high-efficiency TRUE focusing using a large-area photorefractive polymer (5x5 cm^2), which demonstrated ~40 times increase in focused energy. Further, we imaged absorbers embedded in a turbid sample of thickness of ~12 transport mean free paths.", "doi": "10.1117/12.2005021", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85811G" }, { "id": "authors:fn8h4-8ny17", "collection": "authors", "collection_id": "fn8h4-8ny17", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150420938", "type": "book_section", "title": "Measurement of Gr\u00fcneisen parameter of tissue by photoacoustic spectrometry", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Yao", "given_name": "Da-Kang", "clpid": "Yao-Da-Kang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The Gr\u00fcneisen parameter of tissue is a constitutive parameter in photoacoustic tomography. Here, we applied photoacoustic spectrometry (PAS) to directly measure the Gr\u00fcneisen parameter. In our PAS system, laser pulses at wavelengths between 460 and 1600 nm were delivered to tissue samples, and photoacoustic signals were detected by a 20 MHz flat water-immersion ultrasonic transducer. By fitting photoacoustic spectra to light absorption spectra, we found that the Gr\u00fcneisen parameter was 0.73 for porcine subcutaneous fat tissue, and 0.15 for oxygenated bovine red blood cells at room temperature (24\u00b0C).", "doi": "10.1117/12.2004117", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858138" }, { "id": "authors:a6fvg-fp513", "collection": "authors", "collection_id": "a6fvg-fp513", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-101020177", "type": "book_section", "title": "Noninvasive photoacoustic computed tomography of mouse brain metabolism in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Avanaki", "given_name": "Mohammadreza", "clpid": "Avanaki-M-R-N" }, { "family_name": "Tsytsarev", "given_name": "Vassiliy", "clpid": "Tsytsarev-V" }, { "family_name": "Demchenko", "given_name": "Alexei V.", "clpid": "Demchenko-A-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To control the overall action of the body, brain consumes a large amount of energy in proportion to its volume. In humans and many other species, the brain gets most of its energy from oxygen-dependent metabolism of glucose. An abnormal metabolic rate of glucose and/or oxygen usually reflects a diseased status of brain, such as cancer or Alzheimer's disease. We have demonstrated the feasibility of imaging mouse brain metabolism using photoacoustic computed tomography (PACT), a fast, noninvasive and functional imaging modality with optical contrast and acoustic resolution. Brain responses to forepaw stimulations were imaged transdermally and transcranially. 2-NBDG, which diffuses well across the blood-brain-barrier, provided exogenous contrast for photoacoustic imaging of glucose response. Concurrently, hemoglobin provided endogenous contrast for photoacoustic imaging of hemodynamic response. Glucose and hemodynamic responses were quantitatively unmixed by using two-wavelength measurements. We found that glucose uptake and blood perfusion around the somatosensory region of the contralateral hemisphere were both increased by stimulations, indicating elevated neuron activity. The glucose response amplitude was about half that of the hemodynamic response. While the glucose response area was more homogenous and confined within the somatosensory region, the hemodynamic response area showed a clear vascular pattern and spread about twice as wide as that of the glucose response. The PACT of mouse brain metabolism was validated by high-resolution open-scalp OR-PAM and fluorescence imaging. Our results demonstrate that 2-NBDG-enhanced PACT is a promising tool for noninvasive studies of brain metabolism.", "doi": "10.1117/12.2005645", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85814A" }, { "id": "authors:bza1j-e1x29", "collection": "authors", "collection_id": "bza1j-e1x29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-154406451", "type": "book_section", "title": "Anatomical and metabolic small-animal whole-body imaging using ring-shaped confocal photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Chatni", "given_name": "Muhammad", "clpid": "Chatni-M-R" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Due to the wide use of animals for human disease studies, small animal whole-body imaging plays an increasingly important role in biomedical research. Currently, none of the existing imaging modalities can provide both anatomical and glucose metabolic information, leading to higher costs of building dual-modality systems. Even with image coregistration, the spatial resolution of the metabolic imaging modality is not improved. We present a ring-shaped confocal photoacoustic computed tomography (RC-PACT) system that can provide both assessments in a single modality. Utilizing the novel design of confocal full-ring light delivery and ultrasound transducer array detection, RC-PACT provides full-view cross-sectional imaging with high spatial resolution. Scanning along the orthogonal direction provides three-dimensional imaging. While the mouse anatomy was imaged with endogenous hemoglobin contrast, the glucose metabolism was imaged with a near-infrared dye-labeled 2-deoxyglucose. Through mouse tumor models, we demonstrate that RC-PACT may be a paradigm shifting imaging method for preclinical research.", "doi": "10.1117/12.2004937", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85810K" }, { "id": "authors:j7bmt-b8596", "collection": "authors", "collection_id": "j7bmt-b8596", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421560", "type": "book_section", "title": "Combined optical- and acoustic-resolution photoacoustic microscopy based on an optical fiber bundle", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic microscopy (PAM), whose spatial resolution and penetration depth are both scalable, has made great progress in recent years. According to their different lateral resolutions, PAM systems can be categorized into either optical-resolution (OR) PAM, with optical-diffraction-limited lateral resolution, or acoustic-resolution (AR) PAM, with acoustically limited resolution and a deeper maximum imaging depth. In this report, we present a combined OR and AR PAM system with resolutions of 2.2 \u03bcm and 40 \u03bcm, respectively. Sharing most components between the OR and AR implementations, the system achieves separated illumination for OR and AR imaging by an optical fiber bundle through different channels, and two discrete lasers are used to provide either high-power energy for AR imaging or highrepetition- rate pulses for OR imaging. The design enables automatically co-registered OR and AR photoacoustic imaging in one single system, which extends the usability of current photoacoustic systems and simplifies the imaging procedure.", "doi": "10.1117/12.2005259", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858142" }, { "id": "authors:hfnhy-4ne42", "collection": "authors", "collection_id": "hfnhy-4ne42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-150421816", "type": "book_section", "title": "Photoacoustic endoscopic imaging of the rabbit mediastinum", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Li", "given_name": "Chiye", "clpid": "Li-Chiye" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Like ultrasound endoscopy, photoacoustic endoscopy (PAE) could become a valuable addition to clinical practice due to its deep imaging capability. Results from our recent in vivo transesophageal endoscopic imaging study on rabbits demonstrate the technique's capability to image major organs in the mediastinal region, such as the lung, trachea, and cardiovascular systems. Here, we present various features from photoacoustic images from the mediastinal region of several rabbits and discuss possible clinical contributions of this technique and directions of future technology development.", "doi": "10.1117/12.2004980", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "publication_date": "2013-03-04" }, { "id": "authors:78ps5-q2906", "collection": "authors", "collection_id": "78ps5-q2906", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549046", "type": "book_section", "title": "Carbon nanoparticles as a multimodal thermoacoustic and photoacoustic contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Wu", "given_name": "Lina", "clpid": "Wu-Lina" }, { "family_name": "Xing", "given_name": "Wenxin", "clpid": "Xing-Wenxin" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Nie", "given_name": "Liming", "clpid": "Nie-Liming" }, { "family_name": "Zhang", "given_name": "Ruiying", "orcid": "0000-0002-0092-0814", "clpid": "Zhang-Ruiying" }, { "family_name": "Lanza", "given_name": "Gregory M.", "clpid": "Lanza-G-M" }, { "family_name": "Shen", "given_name": "Baozhong", "clpid": "Shen-Baozhong" }, { "family_name": "Pan", "given_name": "Dipanjan", "clpid": "Pan-Dipanjan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We demonstrated the potential of carbon nanoparticles (CNPs) as exogenous contrast agents for both thermoacoustic (TA) tomography (TAT) and photoacoustic (PA) tomography (PAT). In comparison to deionized water, the CNPs provided a four times stronger signal in TAT at 3 GHz. In comparison to blood, The CNPs provided a much stronger signal in PAT over a broad wavelength range of 450-850 nm. Specifically, the maximum signal enhancement in PAT was 9.4 times stronger in the near-infrared window of 635-670 nm. In vivo blood-vessel PA imaging was performed non-invasively on a mouse femoral area. The images, captured after the tail vein injection of CNPs, show a gradual enhancement of the optical absorption in the vessels by up to 230%. The results indicate that CNPs can be potentially used as contrast agents for TAT and PAT to monitor the intravascular or extravascular pathways in clinical applications.", "doi": "10.1117/12.2005064", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858140" }, { "id": "authors:51c40-r5a34", "collection": "authors", "collection_id": "51c40-r5a34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094548257", "type": "book_section", "title": "High resolution functional photoacoustic computed tomography of the mouse brain during electrical stimulation", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Avanaki", "given_name": "Mohammad R. N.", "clpid": "Avanaki-M-R-N" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic computed tomography (PACT) is an emerging imaging technique which is based on the acoustic detection of optical absorption from tissue chromophores, such as oxy-hemoglobin and deoxy-hemoglobin. An important application of PACT is functional brain imaging of small animals. The conversion of light to acoustic waves allows PACT to provide high resolution images of cortical vasculatures through the intact scalp. Here, PACT was utilized to study the activated areas of the mouse brain during forepaw and hindpaw stimulations. Temporal PACT images were acquired enabling computation of hemodynamic changes during stimulation. The stimulations were performed by trains of pulses at different stimulation currents (between 0.1 to 2 mA) and pulse repetition rates (between 0.05 Hz to 0.01Hz). The response at somatosensory cortex-forelimb, and somatosensory cortex-hindlimb, were investigated. The Paxinos mouse brain atlas was used to confirm the activated regions. The study shows that PACT is a promising new technology that can be used to study brain functionality with high spatial resolution.", "doi": "10.1117/12.2004737", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85813K" }, { "id": "authors:1weka-1hg67", "collection": "authors", "collection_id": "1weka-1hg67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-101020280", "type": "book_section", "title": "Water-Immersible MEMS scanning mirror designed for wide-field fast-scanning photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Huang", "given_name": "Chih-Hsien", "clpid": "Huang-Chih-Hsien" }, { "family_name": "Martel", "given_name": "Catherine", "clpid": "Martel-C" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Gao", "given_name": "Liang", "clpid": "Gao-Liang" }, { "family_name": "Randolph", "given_name": "Gwendalyn", "clpid": "Randolph-G-J" }, { "family_name": "Zou", "given_name": "Jun", "orcid": "0000-0002-9543-6135", "clpid": "Zou-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have sacrificed either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible MEMS scanning mirror (MEMS-ORPAM). Made of silicon with a gold coating, the MEMS mirror plate can reflect both optical and acoustic beams. Because it uses an electromagnetic driving force, the whole MEMS scanning system can be submerged in water. In MEMS-ORPAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. A diffraction-limited lateral resolution of 2.4 \u03bcm in water and a maximum imaging depth of 1.1 mm in soft tissue have been experimentally determined. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. By using Evans blue dye as the contrast agent, we also imaged the flow dynamics of lymphatic vessels in a mouse tail in vivo. The results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.", "doi": "10.1117/12.2005669", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 858127" }, { "id": "authors:28wt8-rt007", "collection": "authors", "collection_id": "28wt8-rt007", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180917-094549168", "type": "book_section", "title": "Blood pulse wave velocity measured by photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Yeh", "given_name": "Chenghung", "clpid": "Yeh-Chenghung" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Blood pulse wave velocity (PWV) is an important indicator for vascular stiffness. In this letter, we present electrocardiogram-synchronized photoacoustic microscopy for in vivo noninvasive quantification of the PWV in the peripheral vessels of mice. Interestingly, strong correlation between blood flow speed and ECG were clearly observed in arteries but not in veins. PWV is measured by the pulse travel time and the distance between two spot of a chose vessel, where simultaneously recorded electrocardiograms served as references. Statistical analysis shows a linear correlation between the PWV and the vessel diameter, which agrees with known physiology. Keywords: photoacoustic microscopy, photoacoustic spectroscopy, bilirubin, scattering medium.", "doi": "10.1117/12.2004232", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85812C" }, { "id": "authors:b0fx1-cgn32", "collection": "authors", "collection_id": "b0fx1-cgn32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-101019987", "type": "book_section", "title": "Exploring ultrasound-modulated optical tomography at clinically useful depths using the photorefractive effect", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2013", "author": [ { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "For years, ultrasound-modulated optical tomography (UOT) has been proposed to image optical contrasts deep inside turbid media (such as biological tissue) at an ultrasonic spatial resolution. The reported imaging depth so far, however, has been limited, preventing this technique from finding broader applications. In this work, we present our latest experimental explorations that push UOT to clinically useful imaging depths, achieved through optimizing from different aspects. One improvement is the use of a large aperture fiber bundle, which more effectively collects the diffused light, including both ultrasound-modulated and unmodulated portions, from the turbid sample and then sends it to the photorefractive material. Another endeavor is employment of a large aperture photorefractive polymer film for demodulating the ultrasound-induced phase modulation. Compared with most UOT detection schemes, the polymer film based setup provides a much higher etendue as well as photorefractive two-beam-coupling gain. Experimentally, we have demonstrated enhanced sensitivity and have imaged through tissue-mimicking samples up to 9.4 cm thick at the ultrasonically-determined spatial resolutions.", "doi": "10.1117/12.2003270", "isbn": "9780819493507", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2013-03-04", "pages": "Art. No. 85812X" }, { "id": "authors:7y7aj-1jv05", "collection": "authors", "collection_id": "7y7aj-1jv05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709332", "type": "book_section", "title": "Multi-contrast photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Hu", "given_name": "S.", "clpid": "Hu-Song" }, { "family_name": "Sohn", "given_name": "R.", "clpid": "Sohn-R-E" }, { "family_name": "Lu", "given_name": "Z.-H.", "clpid": "Lu-Z-H" }, { "family_name": "Soetikno", "given_name": "B.", "clpid": "Soetikno-B-T" }, { "family_name": "Zhong", "given_name": "Q.", "clpid": "Zhong-Q" }, { "family_name": "Yao", "given_name": "J.", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "K.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Arbeit", "given_name": "J. M.", "clpid": "Arbeit-J-M" }, { "family_name": "Wang", "given_name": "L. V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We developed multi-contrast photoacoustic microscopy (PAM) for in vivo anatomical, functional, metabolic, and molecular imaging. This technical innovation enables comprehensive understanding of the tumor microenvironment. With multi-contrast PAM, we longitudinally determined tumor vascular anatomy, blood flow, oxygen saturation of hemoglobin, and oxygen extraction fraction.", "doi": "10.1117/12.909754", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-03-15", "pages": "Art. No. 822310" }, { "id": "authors:r0b52-0xq61", "collection": "authors", "collection_id": "r0b52-0xq61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709517", "type": "book_section", "title": "In vivo quantitative evaluation of gold nanocages' kinetics in sentinel lymph nodes by photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Li", "given_name": "Weiyang", "clpid": "Li-Weiyang" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Yuan", "given_name": "Yuchen", "clpid": "Yuan-Yuchen" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "As a new class of sentinel lymph node (SLN) tracers for photoacoustic (PA) imaging, Au nanocages offer the advantages of noninvasiveness, strong optical absorption in the near-infrared region (for deep penetration), and accumulation in higher concentrations than the initial injected solution. By monitoring the amplitude changes of PA signals in an animal model, we quantified the accumulations of nanocages in SLNs over time. Based on this method, we quantitatively evaluated the kinetics of gold nanocages in SLN in terms of concentration, size, and surface modification. We could detect the SLN at an Au nanocage injection concentration of 50 pM and a dose of 100 \u03bcL in vivo. This concentration is about 40 times less than the previously reported value. We also investigated the influence of nanocages' size (50 nm and 30 nm in edge length), and the effects of surface modification (with positive, or neutral, or negative surface charges). The results are helpful to develop this AuNC-based PA imaging system for noninvasive lymph node mapping, providing valuable information about metastatic cancer staging.", "doi": "10.1117/12.909281", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233P" }, { "id": "authors:1cg1a-tgs43", "collection": "authors", "collection_id": "1cg1a-tgs43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709789", "type": "book_section", "title": "Effect of light scattering on optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Liu", "given_name": "Yan", "orcid": "0000-0002-5837-4908", "clpid": "Liu-Yan" }, { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Xu", "given_name": "Zhun", "clpid": "Xu-Zhun" }, { "family_name": "Ferradal", "given_name": "Silvina", "clpid": "Ferradal-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The penetration depth of ballistic optical imaging technologies is limited by light scattering. To study the effect of scattering on optical-resolution photoacoustic microscopy (OR-PAM), we divided the signals in OR-PAM into two classes: one is from the target volume defined by the optical resolution cell (Class I); the other is from the rest of the acoustic resolution cell (Class II). We developed a way to simulate the point spread function (PSF) of our OR-PAM system considering both optical illumination and acoustic detection, then used the PSF to calculate the contributions of each class of signal to the total signal at different focal depths. Our simulation results showed that: 1) The Class II signal decays much more slowly than the Class I signal; 2) The full width at half maximum (FWHM) of the PSF for the focal depth of 0.9 transport mean free path (TMFP) is not broadened much (~10%) compared with that for a clear medium; 3) Image contrast is degraded with increasing depth when there is a uniform absorption background.", "doi": "10.1117/12.909373", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233S" }, { "id": "authors:29w7c-rmr97", "collection": "authors", "collection_id": "29w7c-rmr97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709610", "type": "book_section", "title": "Quantification of optical absorption coefficient from acoustic spectra in the optical diffusive regime using photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic (PA) tomography (PAT) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Multi-wavelength PAT can noninvasively monitor hemoglobin oxygen saturation (sO_2) with high sensitivity and fine spatial resolution. However, accurate quantification in PAT requires knowledge of the optical fluence distribution, acoustic wave attenuation, and detection system bandwidth. We propose a method to circumvent this requirement using acoustic spectra of PA signals acquired at two optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560 and 575 nm were quantified with errors of <5%.", "doi": "10.1117/12.906787", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82234C" }, { "id": "authors:2k4bm-4xy32", "collection": "authors", "collection_id": "2k4bm-4xy32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711130", "type": "book_section", "title": "Ring-shaped confocal photoacoustic computed tomography for small-animal whole-body imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Chatni", "given_name": "Muhammad", "clpid": "Chatni-M-R" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Anastasio", "given_name": "Mark", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report herein a novel three-dimensional photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring ultrasonic transducer array, was cylindrically focused and capable of forming a two-dimensional image in 1.6 seconds. The pulsed laser could either illuminate directly from the top or be reshaped to illuminate the sample from the side. Top illumination was mainly used for mouse brain and mouse embryo imaging. Side illumination provided in vivo anatomical images of an adult mouse. By translating the mouse along the elevational direction, the system provided serial cross-sectional images.", "doi": "10.1117/12.906056", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82230G" }, { "id": "authors:40nz0-ckk47", "collection": "authors", "collection_id": "40nz0-ckk47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710563", "type": "book_section", "title": "Wide range quantitative photoacoustic spectroscopy to measure non-linear optical absorption of hemoglobin", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Danielli", "given_name": "Amos", "clpid": "Danielli-A" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic microscopy (PAM) has been shown to be a valuable tool for quantifying hemoglobin oxygenation within single vessels. Recently, optical-resolution PAM was developed to achieve higher resolution by reducing the laser beam diameter, which increased the light intensity. As intensity increases, saturation of the optical absorption and multiphoton/ multi-step absorption can occur, which, together with the temperature dependence of thermal expansion, result in a non-linear dependence of the photoacoustic signal on the excitation pulse fluence. For hemoglobin, the major absorber in tissue for photoacoustic imaging, these non-linear phenomena have strong wavelength dependence. To enable quantitative photoacoustic measurements at different wavelengths in the presence of nonlinearity, a careful wide range analysis of the intensity-dependent absorption is required. Here, we built a photoacoustic spectrometer, using a tunable nanosecond optical parametric oscillator that operates between 410 nm and 2400 nm as our light source. To reduce uncertainty in our measurements due to inhomogeneous spatial distribution of the optical fluence, we used a flat-top beam illumination and a flat transducer which was mounted in reflection mode, effectively reducing quantitative measurements to a one dimensional problem. Intensity-dependent non-linear spectra of the photoacoustic signals of oxyand deoxy-hemoglobin were obtained. These measurements have the potential to contribute significantly to quantitative functional PAM.", "doi": "10.1117/12.908900", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233H" }, { "id": "authors:475bw-3ed79", "collection": "authors", "collection_id": "475bw-3ed79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710150", "type": "book_section", "title": "Temperature mapping using photoacoustic and thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic (PA) and thermoacoustic (TA) effects are based on the generation of acoustic waves after tissues absorb electromagnetic energy. The amplitude of the acoustic signal is related to the temperature of the absorbing target tissue. A combined photoacoustic and thermoacoustic imaging system built around a modified commercial ultrasound scanner was used to obtain an image of the target's temperature, using reconstructed photoacoustic or thermoacoustic images. To demonstrate these techniques, we used photoacoustic imaging to monitor the temperature changes of methylene blue solution buried at a depth of 1.5 cm in chicken breast tissue from 12 to 42 \u00b0C. We also used thermoacoustic imaging to monitor the temperature changes of porcine muscle embedded in 2 cm porcine fat from 14 to 28 \u00b0C. The results demonstrate that these techniques can provide noninvasive real-time temperature monitoring of embedded objects and tissue.", "doi": "10.1117/12.909000", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82230T" }, { "id": "authors:6kefz-pm530", "collection": "authors", "collection_id": "6kefz-pm530", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709426", "type": "book_section", "title": "Vessel segmentation analysis of ischemic stroke images acquired with photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Soetikno", "given_name": "Brian", "clpid": "Soetikno-B-T" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Gonzales", "given_name": "Ernie", "clpid": "Gonzales-E" }, { "family_name": "Zhong", "given_name": "Qiaonan", "clpid": "Zhong-Qiaonan" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Lee", "given_name": "Jin-Moo", "clpid": "Lee-Jin-Moo" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have applied optical-resolution photoacoustic microscopy (OR-PAM) for longitudinal monitoring of cerebral metabolism through the intact skull of mice before, during, and up to 72 hours after a 1-hour transient middle cerebral artery occlusion (tMCAO). The high spatial resolution of OR-PAM enabled us to develop vessel segmentation techniques for segment-wise analysis of cerebrovascular responses.", "doi": "10.1117/12.911089", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 822345" }, { "id": "authors:6rz4t-2f002", "collection": "authors", "collection_id": "6rz4t-2f002", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709935", "type": "book_section", "title": "Double-illumination photoacoustic microscopy of intestinal hemodynamics following massive small bowel resection", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Rowland", "given_name": "Kathryn J.", "clpid": "Rowland-K-J" }, { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Warner", "given_name": "Brad W.", "clpid": "Warner-B-W" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Massive small bowel resection (SBR) results in villus angiogenesis and intestinal adaptation. The exact mechanism that causes intestinal villus angiogenesis remains unknown. We hypothesize that hemodynamic changes within the remnant bowel after SBR will trigger intestinal angiogenesis. To validate this, we used photoacoustic microscopy (PAM) to image the microvascular system of the intestine in C57B6 mice and to measure blood flow and oxygen saturation (sO_2) of a supplying artery and vein. Baseline measurements were made 6 cm proximal to the ileal-cecal junction (ICJ) prior to resection. A 50% proximal bowel resection was then performed, and measurements were again recorded at the same location immediately, 1, 3 and 7 days following resection. The results show that arterial and venous sO_2 were similar prior to SBR. Immediately following SBR, the arterial and venous sO_2 decreased by 14.3 \u00b1 2.7% and 32.7 \u00b1 6.6%, respectively, while the arterial and venous flow speed decreased by 62.9 \u00b1 17.3% and 60.0 \u00b1 20.1%, respectively. Such significant decreases in sO_2 and blood flow indicate a hypoxic state after SBR. Within one week after SBR, both sO2 and blood flow speed had gradually recovered. By 7 days after SBR, arterial and venous sO_2 had increased to 101.0 \u00b1 2.9% and 82.7 \u00b1 7.3% of the baseline values, respectively, while arterial and venous flow speed had increased to 106.0 \u00b1 21.4% and 150.0 \u00b1 29.6% of the baseline values, respectively. Such increases in sO_2 and blood flow may result from angiogenesis following SBR.", "doi": "10.1117/12.909508", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233V" }, { "id": "authors:79x3j-44v96", "collection": "authors", "collection_id": "79x3j-44v96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709994", "type": "book_section", "title": "Transcranial photoacoustic tomography of the monkey brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Nie", "given_name": "Liming", "clpid": "Nie-Liming" }, { "family_name": "Huang", "given_name": "Chao", "clpid": "Huang-Chao" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Anastasio", "given_name": "Mark", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A photoacoustic tomography (PAT) system using a virtual point ultrasonic transducer was developed for transcranial imaging of monkey brains. The virtual point transducer provided a 10 times greater field-of-view (FOV) than finiteaperture unfocused transducers, which enables large primate imaging. The cerebral cortex of a monkey brain was accurately mapped transcranially, through up to two skulls ranging from 4 to 8 mm in thickness. The mass density and speed of sound distributions of the skull were estimated from adjunct X-ray CT image data and utilized with a timereversal algorithm to mitigate artifacts in the reconstructed image due to acoustic aberration. The oxygenation saturation (sO_2) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. The oxygenation saturation (sO_2) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. Our experimental results demonstrate that PAT can overcome the optical and ultrasound attenuation of a relatively thick skull, and the imaging aberration caused by skull can be corrected to a great extent.", "doi": "10.1117/12.907060", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82230L" }, { "id": "authors:8bxkq-37z66", "collection": "authors", "collection_id": "8bxkq-37z66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710306", "type": "book_section", "title": "The study of quantitative optical absorption imaging by using Monte Carlo simulation of combined photoacoustic tomography and ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Li", "given_name": "Yang", "orcid": "0000-0002-4939-8174", "clpid": "Li-Yang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We demonstrate the feasibility of quantitative optical absorption imaging by using Monte Carlo simulation of combined photoacoustic tomography (PAT) and ultrasound-modulated optical tomography (UOT). Our simulation results show that the optical fluence on initial photoacoustic (PA) pressure waves can be accurately compensated for recovering exact optical absorption coefficients by using a fluence map acquired from UOT signals. Further, when the optical heterogeneities of a sample were varied, the recovered optical absorption coefficients from a target remained constant while PA amplitudes fluctuated. In practice, PAT and UOT systems can be potentially combined because both imaging systems can easily share light illumination and ultrasound application patterns.", "doi": "10.1117/12.905792", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82232C" }, { "id": "authors:8m7dd-9fa38", "collection": "authors", "collection_id": "8m7dd-9fa38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710092", "type": "book_section", "title": "Photoacoustic speckles: boundary dependence and experimental validation", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Xu", "given_name": "Zhun", "clpid": "Xu-Zhun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography (PAT) suppresses speckles by prominent boundary buildups. We theoretically study the dependence of PAT speckles on the boundary roughness, which is quantified by the root-mean-squared (RMS) value and the correlation length of the height. The speckle visibility and the correlation coefficient between the reconstructed and actual boundaries are quantified as a function of the boundary roughness. The statistics of PAT speckles is studied experimentally.", "doi": "10.1117/12.906792", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82232M" }, { "id": "authors:9k8yk-ctf92", "collection": "authors", "collection_id": "9k8yk-ctf92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710635", "type": "book_section", "title": "Photoacoustic microscopy of myocardial sheet architecture in unfixed and unstained mammalian hearts", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Cheng", "given_name": "Ya-Jian", "clpid": "Cheng-Ya-Jian" }, { "family_name": "Yao", "given_name": "Da-Kang", "clpid": "Yao-Da-Kang" }, { "family_name": "Wickline", "given_name": "Samuel", "clpid": "Wickline-S-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The laminar myocardial sheet architecture and its dynamic change play a key role in myocardial wall thickening. Histology, confocal optical microscopy (COM), and diffusion tensor MRI (DTI) have been used to unveil the structures and functions of the myocardial sheets. However, histology and COM require fixation, sectioning, and staining processes, which dehydrate and deform the sheet architecture. Although DTI can delineate sheet architecture nondestructively in viable hearts, it cannot provide cellular-level resolution. Here we show that photoacoustic microscopy (PAM), with high resolution (~1 \u03bcm) and label-free detection, is appropriate for imaging 3D myocardial architecture. Perfused half-split mouse hearts were also imaged by PAM in vitro without fixation, dehydration, nor staining. The laminar myocardial sheet architecture was clearly visualized within a 0.15 mm depth range. Two populations of oppositely signed sheet angles were observed. Therefore, PAM promises to access dynamic changes of myocardial architectures in ex vivo perfused-viable hearts.", "doi": "10.1117/12.906208", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82232G" }, { "id": "authors:bk94z-kdf36", "collection": "authors", "collection_id": "bk94z-kdf36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710485", "type": "book_section", "title": "DMD-encoded spectral photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a spectrally encoded photoacoustic microscope based on a digital mirror device (DMD). It enables fast spatially resolved spectral measurements of optical absorption. The imaging system can quickly tune the laser illumination spectrum at the laser pulse repetition rate of 2 kHz. To demonstrate multi-wavelength absorption measurements, we imaged optically absorbing solution phantom. Compared with spectral scanning, spectral encoding recovers chromophore absorption spectra with improved accuracy by enhancing photoacoustic amplitude signal-to-noise ratio.", "doi": "10.1117/12.910521", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 822312" }, { "id": "authors:by83p-dwc51", "collection": "authors", "collection_id": "by83p-dwc51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710964", "type": "book_section", "title": "Photoacoustic imaging of the near-infrared fluorescent protein iRFP in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Krumholz", "given_name": "Arie", "clpid": "Krumholz-A" }, { "family_name": "Filonov", "given_name": "Grigory S.", "clpid": "Filonov-G-S" }, { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Verkhusha", "given_name": "Vladislav V.", "orcid": "0000-0002-2083-8121", "clpid": "Verkhusha-V-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Genetically encoded probes powerfully and non-invasively target specific tissues, cells, and subcellular locations. iRFP, a novel near-infrared fluorescent protein with low quantum yield whose absorption and fluorescence maxima are located at wavelengths longer than the Q-band of hemoglobin absorption, is ideal for PAT. Here, we report on an in vitro comparison of iRFP with other far-red fluorescent proteins, and its use in imaging a mouse tumor xenograft model. In an in vivo experiment, we stably transfected iRFP into MTLn3 adenocarcinoma cells and injected them into the mammary fat pad of female SCID/NCr mice, then imaged the resulting tumors two and three weeks post injection. The contrast increase from the protein expression was high enough to clearly separate the tumor region from the rest of the animal.", "doi": "10.1117/12.908927", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233A" }, { "id": "authors:cfvrq-bev72", "collection": "authors", "collection_id": "cfvrq-bev72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711236", "type": "book_section", "title": "Functional photoacoustic microscopy of pH", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Chatni", "given_name": "M. Rameez", "clpid": "Chatni-M-R" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Danielli", "given_name": "Amos", "clpid": "Danielli-A" }, { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "pH is a tightly regulated indicator of metabolic activity. In mammalian systems, imbalance of pH regulation may result from or result in serious illness. Even though the regulation system of pH is very robust, tissue pH can be altered in many diseases such as cancer, osteoporosis and diabetes mellitus. Traditional high-resolution optical imaging techniques, such as confocal microscopy, routinely image pH in cells and tissues using pH sensitive fluorescent dyes, which change their fluorescence properties with the surrounding pH. Since strong optical scattering in biological tissue blurs images at greater depths, high-resolution pH imaging is limited to penetration depths of 1mm. Here, we report photoacoustic microscopy (PAM) of commercially available pH-sensitive fluorescent dye in tissue phantoms. Using both opticalresolution photoacoustic microscopy (OR-PAM), and acoustic resolution photoacoustic microscopy (AR-PAM), we explored the possibility of recovering the pH values in tissue phantoms. In this paper, we demonstrate that PAM was capable of recovering pH values up to a depth of 2 mm, greater than possible with other forms of optical microscopy.", "doi": "10.1117/12.907685", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82230N" }, { "id": "authors:escp7-p1978", "collection": "authors", "collection_id": "escp7-p1978", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710797", "type": "book_section", "title": "Ultrasonic encoding of diffused light: from optical imaging to light focusing in turbid media", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Liu", "given_name": "Honglin", "orcid": "0000-0003-2473-9056", "clpid": "Liu-Honglin" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In optical scattering media such as biological tissue, light propagation is randomized by multiple scattering. Beyond one transport mean free path, where photon propagation is in the diffusive regime, direct light focusing becomes infeasible. The resulting loss of light localization poses serious challenge to optical imaging in thick scattering media. Ultrasound modulated optical tomography (UOT) combines high optical contrast and good ultrasonic resolution, and is therefore an ideal imaging modality for soft biological tissue. A variety of detection techniques have been developed in UOT in an effort to discriminate the ultrasonically encoded diffused light as the imaging signal. We developed a photorefractive crystal based detection system, which has the ability to image both the optical and acoustic properties of biological tissues. With the improved photorefractive crystal based detection, tissue-mimicking phantom samples as thick as 9.4 cm can be imaged. We further exploit the virtual source concept in UOT and combine it with optical time reversal to achieve diffusive light focusing into scattering media. Experimental implementation of this new technology is presented.", "doi": "10.1117/12.909916", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 822324" }, { "id": "authors:gag78-pf951", "collection": "authors", "collection_id": "gag78-pf951", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709702", "type": "book_section", "title": "A 2.5-mm outer diameter photoacoustic endoscopic mini-probe based on a highly sensitive PMN-PT ultrasonic transducer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have developed a 2.5-mm outer diameter photoacoustic endoscopic mini-probe to use in the instrument channel (typically 2.8 or 3.7 mm in diameter) of standard video endoscopes. To achieve adequate signal sensitivity, we fabricated a focused ultrasonic transducer using a highly-sensitive PMN-PT piezoelectric material. We quantified the PMN-PT transducer's operating parameters and validated the mini-probe's endoscopic imaging capability through an ex vivo imaging experiment on a rat colon.", "doi": "10.1117/12.909207", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233M" }, { "id": "authors:j3f1h-1cm11", "collection": "authors", "collection_id": "j3f1h-1cm11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709848", "type": "book_section", "title": "Dichroism optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Hu", "given_name": "S.", "clpid": "Hu-Song" }, { "family_name": "Maslov", "given_name": "K.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Yan", "given_name": "Ping", "clpid": "Yan-Ping" }, { "family_name": "Lee", "given_name": "Jin-Moo", "clpid": "Lee-Jin-Moo" }, { "family_name": "Wang", "given_name": "L. V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have developed dichroism optical-resolution photoacoustic microscopy, capable of imaging polarization-dependent optical absorption (i.e., dichroism) with excellent specificity. This technical innovation enriches molecular photoacoustic contrasts and holds particular potential for detecting amyloid-associated neurodegenerative and cardiovascular diseases.", "doi": "10.1117/12.909401", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82233T" }, { "id": "authors:mtaa0-s6j77", "collection": "authors", "collection_id": "mtaa0-s6j77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711322", "type": "book_section", "title": "In vivo imaging of cell nuclei by photoacoustic microscopy without staining", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Yao", "given_name": "Da-Kang", "clpid": "Yao-Da-Kang" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultraviolet photoacoustic microscopy (UVPAM) can image cell nuclei in vivo with high contrast and resolution noninvasively without staining. Here, we used UV light at wavelengths of 210-310 nm for excitation of DNA and RNA to produce photoacoustic waves. We applied the UVPAM to in vivo imaging of cell nuclei in mouse skin, and obtained UVPAM images of the unstained cell nuclei at wavelengths of 245-282 nm as ultrasound gel was used for acoustic coupling. The largest ratio of contrast to noise was found for the images of cell nuclei at a 250 nm wavelength.", "doi": "10.1117/12.906211", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82231X" }, { "id": "authors:np67w-wg074", "collection": "authors", "collection_id": "np67w-wg074", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710254", "type": "book_section", "title": "Towards nonionizing photoacoustic cystography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Jeon", "given_name": "Mansik", "clpid": "Jeon-Mansik" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Normally, urine flows down from kidneys to bladders. Vesicoureteral reflux (VUR) is the abnormal flow of urine from bladders back to kidneys. VUR commonly follows urinary tract infection and leads to renal infection. Fluoroscopic voiding cystourethrography and direct radionuclide voiding cystography have been clinical gold standards for VUR imaging, but these methods are ionizing. Here, we demonstrate the feasibility of a novel and nonionizing process for VUR mapping in vivo, called photoacoustic cystography (PAC). Using a photoacoustic (PA) imaging system, we have successfully imaged a rat bladder filled with clinically being used methylene blue dye. An image contrast of ~8 was achieved. Further, spectroscopic PAC confirmed the accumulation of methylene blue in the bladder. Using a laser pulse energy of less than 1 mJ/cm2, bladder was clearly visible in the PA image. Our results suggest that this technology would be a useful clinical tool, allowing clinicians to identify bladder noninvasively in vivo.", "doi": "10.1117/12.905793", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82231U" }, { "id": "authors:ptr2n-n9q07", "collection": "authors", "collection_id": "ptr2n-n9q07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710720", "type": "book_section", "title": "Analysis of the role of shear waves in transcranial photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Schoonover", "given_name": "Robert W.", "clpid": "Schoonover-R-W" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report on an investigation of the role of shear waves in transcranial PAT brain imaging. Using a recently developed PAT image reconstruction method for use with layered media, we quantify the extent to which accounting for shear waves in the reconstruction method can improve image quality. The effects of shear waves propagating in the solid layer on the ability to estimate Fourier components of the object are investigated as a function of the thickness of the layer supporting shear waves as well as the incidence angle of the field in the planewave representation. These results clarify the role of shear waves in transcranial PAT image formation and indicate that further research is warranted to develop reconstruction algorithms that account for shear waves.", "doi": "10.1117/12.907389", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 822320" }, { "id": "authors:r8a3w-rk657", "collection": "authors", "collection_id": "r8a3w-rk657", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711050", "type": "book_section", "title": "In vivo photoacoustic tomography of total blood flow and Doppler angle", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "As two hallmarks of cancer, angiogenesis and hypermetabolism are closely related to increased blood flow. Volumetric blood flow measurement is important to understanding the tumor microenvironment and developing new means to treat cancer. Current photoacoustic blood flow estimation methods focus on either the axial or transverse component of the flow vector. Here, we propose a method to compute the total flow speed and Doppler angle by combining the axial and transverse flow measurements. Both the components are measured in M-mode. Collating the A-lines side by side yields a 2D matrix. The columns are Hilbert transformed to compare the phases for the computation of the axial flow. The rows are Fourier transformed to quantify the bandwidth for the computation of the transverse flow. From the axial and transverse flow components, the total flow speed and Doppler angle can be derived. The method has been verified by flowing bovine blood in a plastic tube at various speeds from 0 to 7.5 mm/s and at Doppler angles from 30 to 330\u00b0. The measurement error for total flow speed was experimentally determined to be less than 0.3 mm/s; for the Doppler angle, it was less than 15\u00b0. In addition, the method was tested in vivo on a mouse ear. The advantage of this method is simplicity: No system modification or additional data acquisition is required to use our existing system. We believe that the proposed method has the potential to be used for cancer angiogenesis and hypermetabolism imaging.", "doi": "10.1117/12.909480", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82230U" }, { "id": "authors:v1c70-hqc09", "collection": "authors", "collection_id": "v1c70-hqc09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710428", "type": "book_section", "title": "Photoacoustic and thermoacoustic imaging with a multichannel breast scanner", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Huang", "given_name": "Bin", "clpid": "Huang-Bin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic and thermoacoustic phantom images obtained with a multi-channel breast scanner designed for breast cancer screening are presented here. A tunable laser system (OPOTEK Vibrant 355 I, Calsbad,CA) with a pulse duration of 5 ns was used for photoacoustic irradiation, and a 3.0 GHz microwave source with a pulse width of 0.3-1 \u03bcs was used for thermoacoustic tomography. Multiple (>=16) 2.25 MHz single-element unfocused ultrasonic transducers at different depths were scanned simultaneously for a full 360\u00b0 to obtain a full data set for three-dimensional (3D) tomography. Negative acoustic lenses were attached to these unfocused transducers to increase their acceptance angles. An ultrasound receiving system with 64 parallel receiving channels (Verasonics Inc. Redmond, WA) was used for data acquisition. A filtered backprojection algorithm was used to reconstruct two-dimensional (2D) and 3D images. Different phantoms were imaged to evaluate the performance of the scanner. A lateral resolution of less than 1 mm and an elevational resolution of less than 5 mm were achieved. The phantom studies demonstrate that this scanner can potentially provide high-resolution, dual-modality, three-dimensional images and can potentially be used for human breast cancer screening.", "doi": "10.1117/12.906779", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 822309" }, { "id": "authors:w0y65-rg305", "collection": "authors", "collection_id": "w0y65-rg305", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140710881", "type": "book_section", "title": "Label-free photoacoustic microscopy of cytochrome c in cells", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Zhang", "given_name": "Yu", "orcid": "0000-0001-8938-1927", "clpid": "Zhang-Yu" }, { "family_name": "Yao", "given_name": "Da-Kang", "clpid": "Yao-Da-Kang" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Cytochrome c is a heme protein normally bound to mitochondria and is important for mitochondrial electron transport and apoptosis initiation. Since cytochrome c is nonfluorescent, it is always labeled with fluorescent molecules for imaging, which, however, may affect normal cellular functions. Here, label-free photoacoustic microscopy (PAM) of mitochondrial cytochrome c was realized for the first time by utilizing the optical absorption around the Soret peak. PAM was demonstrated to be sensitive enough to image mitochondrial cytochrome c at 422 nm wavelength. Mitochondrial cytochrome c in the cytoplasm of fixed fibroblasts was clearly imaged by PAM as confirmed by fluorescent labeling. By showing mitochondrial cytochrome c in various cells, we demonstrated the feasibility of PAM for label-free histology of mouse ear sections. Therefore, PAM can sensitively image cytochrome c in unstained cells at 422 nm wavelength and has great potential for functional imaging of cytochrome c in live cells or in vivo.", "doi": "10.1117/12.906202", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-23", "pages": "Art. No. 82231W" }, { "id": "authors:q6sxy-19p31", "collection": "authors", "collection_id": "q6sxy-19p31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711414", "type": "book_section", "title": "Toward dual-wavelength functional photoacoustic endoscopy: laser and peripheral optical systems development", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic endoscopy (PAE) provides unique functional information with high spatial resolution at super depths. The provision of functional information is predicated on its strong spectroscopic imaging ability, and its deep imaging capability is derived from its ultrasonic detection of diffused photon absorption. To accurately image functional physiological parameters, it is necessary to rapidly alternate laser pulses of sufficient energy and different wavelengths. In this study, we developed peripheral optical systems for PAE based on two identical pulsed-laser systems to achieve the fast laser wavelength switching that is essential for accurate functional imaging. Each laser system was comprised of a tunable dye laser pumped by a solid-state, diode-pumped Nd:YLF laser. Both systems deliver adequate energy at the scanning head of the endoscope for imaging biological tissue in the optically diffusive regime (~0.3-0.6 mJ per pulse with a repetition rate of ~1 kHz). In this paper, we introduce the employed laser systems and design of the light delivery optics, and present results from an ex vivo animal imaging experiment that validates the system's multi-wavelength functional imaging capability.", "doi": "10.1117/12.909163", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-09", "pages": "Art. No. 822316" }, { "id": "authors:6vcqe-17v32", "collection": "authors", "collection_id": "6vcqe-17v32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140711507", "type": "book_section", "title": "Time-reversed ultrasonically encoded (TRUE) optical focusing in reflection mode: demonstrations in tissue mimicking phantoms and ex vivo tissue", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2012", "author": [ { "family_name": "Lai", "given_name": "Puxiang", "clpid": "Lai-Puxiang" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Liu", "given_name": "Honglin", "orcid": "0000-0003-2473-9056", "clpid": "Liu-Honglin" }, { "family_name": "Suzuki", "given_name": "Yuta", "clpid": "Suzuki-Yuta" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The problem of how to effectively deliver light dynamically to a small volume inside turbid media has been intensively investigated for imaging and therapeutic purposes. Most recently, a new modality termed Time-Reversed Ultrasonically Encoded (TRUE) optical focusing was proposed by integrating the concepts of ultrasound modulation of diffused light with optical phase conjugation. In this work, the diffused photons that travel through the ultrasound focal region are \"tagged\" with a frequency shift due to the ultrasound modulation. Part of the tagged light is collected in reflection mode and transmitted to a photorefractive crystal, forming there a stationary hologram through interference with a coherent reference optical beam. The hologram is later read by a conjugated optical beam, generating a phase conjugated wavefront of the tagged light. It is conveyed back to the turbid medium in reflection mode, and eventually converges to the ultrasound focal zone. Optical focusing effects from this system are demonstrated experimentally in tissue-mimicking phantoms and ex vivo chicken breast tissue, achieving effective round-trip optical penetration pathlength (extinction coefficient multiplied by round-trip focusing depth) exceeding 160 and 100, respectively. Examples of imaging optical inclusions with this system are also reported.", "doi": "10.1117/12.906017", "isbn": "9780819488664", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2012-02-09", "pages": "Art. No. 82231B" }, { "id": "authors:37max-yqf08", "collection": "authors", "collection_id": "37max-yqf08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130935097", "type": "book_section", "title": "Quantitative high-resolution photoacoustic spectroscopy by combining photoacoustic imaging with diffuse optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Bauer", "given_name": "Adam Q.", "clpid": "Bauer-A-Q" }, { "family_name": "Nothdurft", "given_name": "Ralph E.", "clpid": "Nothdurft-R-E" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Culver", "given_name": "Joseph P.", "clpid": "Culver-J-P" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The specificity of both molecular and functional photoacoustic (PA) images depends on the accuracy of the photoacoustic absorption spectroscopy. Because the PA signal is a product of both the optical absorption coefficient and the local light fluence, quantitative PA measurements of absorption require an accurate estimate of the optical fluence. Lightmodeling aided by diffuse optical tomography (DOT) methods can be used to provide the required fluence map and to reduce errors in traditional PA spectroscopic analysis. As a proof-ofconcept, we designed a phantom to demonstrate artifacts commonly found in photoacoustic tomography (PAT) and how fluence-related artifacts in PAT images can lead to misrepresentations of tissue properties. Specifically, we show that without accounting for fluence-related inhomogeneities in our phantom, errors in estimates of the absorption coefficient from a PAT image were as much as 33%. To correct for this problem, DOT was used to reconstruct spatial distributions of the absorption coefficients of the phantom, and along with the surface fluence distribution from the PAT system, we calculated the fluence everywhere in the phantom. This fluence map was used to correct PAT images of the phantom, reducing the error in the estimated absorption coefficient from the PAT image to less than 5%. Thus, we demonstrate experimentally that combining DOT with PAT can significantly reduce fluence-related errors in PAT images, as well as produce quantitatively accurate, highresolution images of the optical absorption coefficient.", "doi": "10.1117/12.875549", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-28", "pages": "Art. No. 78993O" }, { "id": "authors:q3a6e-6fg69", "collection": "authors", "collection_id": "q3a6e-6fg69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934928", "type": "book_section", "title": "Effects of calibration factors and intensity dependent non-linearity on functional photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Danielli", "given_name": "Amos", "clpid": "Danielli-A" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Krumholz", "given_name": "Arie", "clpid": "Krumholz-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Functional photoacoustic microscopy is a valuable tool in quantifying hemoglobin oxygenation within single vessels. In several functional studies with this tool, quantitative sO_2 measurements were taken both in vitro and in vivo. Although in vitro measurements of sO_2 showed high agreement with expected values from premade samples, in practice, in vivo measurements were less accurate. The reported values of 70%-100% sO_2 in the arteries present large deviations from the expected range of 95-100%. Several factors, such as fluence wavelength dependence, optical wavelength range, and transducer central frequency have been suggested and investigated in order to understand these discrepancies. Despite additional knowledge of systematic errors arising from such factors, measuring the absolute value of sO_2 in vivo remains a challenge. All previous studies assumed linear dependence of the photoacoustic signal on absorption and used the linear least squares model. However, several factors, such as wavelength calibration errors, photodiode-wavelength dependence, and intensity dependent non-linearity, all of which may have a significant effect on the final calculation, have not been investigated. Here we evaluate both in vitro and in vivo the effects on sO_2 measurements of photodiode wavelength dependence, laser wavelength accuracy, and intensity dependent absorption of oxygenated and deoxygenated hemoglobin. We show that these factors may contribute significantly to the deviations in sO_2 calculations in vivo.", "doi": "10.1117/12.875287", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-28", "pages": "Art. No. 78993C" }, { "id": "authors:p4wj1-q1190", "collection": "authors", "collection_id": "p4wj1-q1190", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130935008", "type": "book_section", "title": "Optimal oblique light illumination for photoacoustic microscopy beyond the diffusion limit", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To image beyond the quasi-ballistic photon regime, photoacoustic tomography systems must rely on diffuse photons; however, there still exists an optimal illumination pattern that results in the largest number of photons reaching a target at a given depth. Many photoacoustic imaging systems incorporate weak optical focusing through oblique or dark-field illumination, but these systems are not often optimized for deep light delivery. Multiple parameters and constraints, particularly for in vivo imaging, need to be considered to determine the optimal illumination scheme for a given system: beam diameter, incident angle, pulse repetition rate, laser fluence, and target depth. Monte Carlo simulations of varied beam geometries and incident angles show the best optical illumination schemes for different imaging depths. Further an analytic model based on the diffusion theory provides a rapid method of determining the optimal beam size and incident angle for a given target depth and agrees well with the simulations. The results reveal the most efficient optical focal position to maximize the number of photons delivered to a target depth, therein maximizing the PA signal. The principles and results discussed here are not limited to the system investigated, but can be applied to other system configurations to improve the photoacoustic signal strength.", "doi": "10.1117/12.874903", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-28", "pages": "Art. No. 78990O" }, { "id": "authors:pk9yq-m7734", "collection": "authors", "collection_id": "pk9yq-m7734", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-134410809", "type": "book_section", "title": "In vivo multiscale photoacoustic microscopy of human skin", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Huang", "given_name": "Victor", "clpid": "Huang-Victor" }, { "family_name": "Jassim", "given_name": "Omar", "clpid": "Jassim-O" }, { "family_name": "Cornelius", "given_name": "Lynn A.", "clpid": "Cornelius-L-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Scalability is a key feature of photoacoustic microscopy (PAM). Reports have shown that PAM systems can be designed to possess sub-micron resolution at shallow depths or penetrate centimeters deep at the expense of resolution while the number of resolved pixels in the depth direction remains high. This capability to readily tune the imaging parameters while maintaining the same inherent contrast could be extremely useful for a variety of biomedical applications. Human skin, with its layered vascular structure whose dimensions scale with depth, provides an ideal imaging target to illustrate this advantage. Here, we present results from in vivo human skin imaging experiments using two different PAM systems, an approach which enables better characterization of the cutaneous microvasculature throughout the imaging depth. Specifically, we show images from several distinct areas of skin: the palm and the forearm. For each region, the same area was imaged with both an optical-resolution PAM (OR-PAM) and an acoustic-resolution PAM (AR-PAM), and the subsequent images were combined into composite images. The OR-PAM provides less than 5 \u03bcm lateral resolution, capable of imaging the smallest capillary vessels, while the AR-PAM enables imaging at depths of several millimeters. Several structures are identifiable in the ORPAM images which cannot be differentiated in AR-PAM images, namely thin epidermal and stratum corneum layers, undulations in the dermal papillae, and capillary loops. However, the AR-PAM provides images of larger vessels, deeper than the OR-PAM can penetrate. These results demonstrate how PAM's scalability can be utilized to more fully characterize cutaneous vasculature, potentially impacting the assessment of numerous cardiovascular related and cutaneous diseases.", "doi": "10.1117/12.875969", "isbn": "9780819484369", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-22", "pages": "Art. No. 789946" }, { "id": "authors:wxwc8-hyw92", "collection": "authors", "collection_id": "wxwc8-hyw92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-135658990", "type": "book_section", "title": "Combined ultrasonic and photoacoustic system for deep tissue imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A combined ultrasonic and photoacoustic imaging system is presented that is capable of deep tissue imaging. The system consists of a modified clinical ultrasound array system and tunable dye laser pumped by a Nd:YAG laser. The system is designed for noninvasive detection of sentinel lymph nodes and guidance of needle biopsies for axillary lymph node staging in breast cancer patients. Using a fraction of the American National Standards Institute (ANSI) safety limit, photoacoustic imaging of methylene blue achieved penetration depths of greater than 5 cm in chicken breast tissue. Photoacoustic imaging sensitivity was measured by varying the concentration of methylene blue dye placed at a depth of 3 cm within surrounding chicken breast tissue. Signal-to-noise ratio, noise equivalent sensitivity, and axial spatial resolution were quantified versus depth based on in vivo and chicken breast tissue experiments. The system has been demonstrated in vivo for detecting sentinel lymph nodes in rats following intradermal injection of methylene blue. These results highlight the clinical potential of photoacoustic image-guided identification and needle biopsy of sentinel lymph nodes for axillary staging in breast cancer patients.", "doi": "10.1117/12.874914", "isbn": "9780819484369", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-22", "pages": "Art. No. 789935" }, { "id": "authors:vzf83-c0m98", "collection": "authors", "collection_id": "vzf83-c0m98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934836", "type": "book_section", "title": "Photoacoustic and thermoacoustic tomography of dog prostates", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Ke", "given_name": "Haixin", "clpid": "Ke-Haixin" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Grubb", "given_name": "Robert L., III", "clpid": "Grubb-R-L-III" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We developed a tri-modal system combining photoacoustic (PA) tomography, thermoacoustic (TA) tomography, and ultrasound (US) imaging. Acquired images of an excised dog prostate were compared to histology results. All three modalities can image distinct features. Features like the urethra were shown in both TA and US images, but TA gave a higher contrast-to-noise ratio. Fibrous tissue was more clearly imaged by TA, while the duct structure was better shown in PA images. These experimental results demonstrate the potential advantages of our tri-modal imaging system.", "doi": "10.1117/12.875073", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-22", "pages": "Art. No. 789938" }, { "id": "authors:e5a4m-c4g18", "collection": "authors", "collection_id": "e5a4m-c4g18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140310961", "type": "book_section", "title": "Second generation optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We developed a second-generation optical-resolution photoacoustic microscope (OR-PAM) with a novel acoustic detection scheme, which improved upon the sensitivity of our first-generation system by 18 dB. Moreover, translating the imaging head instead of the living object improved the scanning speed by a factor of 5, widening the field of view within the same acquisition time. The anatomy and hemoglobin oxygen saturation of an entire mouse ear was imaged in vivo.", "doi": "10.1117/12.874786", "isbn": "9780819484369", "publisher": "Society of Photo-Optical Instrumentation Engineers", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-22", "pages": "Art. No. 789933" }, { "id": "authors:2w28w-0hq78", "collection": "authors", "collection_id": "2w28w-0hq78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934742", "type": "book_section", "title": "Dual-mode photoacoustic microscopy of carbon nanotube incorporated scaffolds in blood and biological tissues", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Paratala", "given_name": "Bhavna", "clpid": "Paratala-B-S" }, { "family_name": "Sitharaman", "given_name": "Balaji", "clpid": "Sitharaman-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Three-dimensional scaffolds provide physical support and an adjustable microenvironment to facilitate vascularization of ischemic tissues; however, in vivo imaging of scaffold functioning is still challenging. Micro-CT, the current frequentlyused imaging modality for scaffold characterization, provides poor contrast for wet scaffold, which limits its in vivo applications. In this paper, dual modes of photoacoustic microscopy (PAM), using acoustic resolution PAM (AR-PAM) and optical resolution PAM (OR-PAM), were employed for imaging scaffolds in blood as well as in chicken breast tissues. By choosing different wavelengths, 570 nm and 638 nm, we spectroscopically differentiated the photoacoustic signals generated from blood and from carbon nanotube incorporated scaffolds. The ex vivo experiments demonstrated a lateral resolution of 45 \u03bcm and a maximum penetration of ~2 mm for AR-PAM, and a lateral resolution of 3 \u03bcm and a maximum penetration of ~660 \u03bcm for OR-PAM. OR-PAM further quantified the average pore size of scaffolds to be 100-200 \u03bcm in diameter. Our results suggest that PAM is a promising tool for in vivo monitoring of scaffold-induced angiogenesis as well as the degradability of scaffolds themselves.", "doi": "10.1117/12.873230", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-18", "pages": "Art. No. 78992I" }, { "id": "authors:n8z72-3bt02", "collection": "authors", "collection_id": "n8z72-3bt02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934656", "type": "book_section", "title": "Focusing light into turbid media: time-reversed ultrasonically encoded (TRUE) focusing", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Liu", "given_name": "Honglin", "orcid": "0000-0003-2473-9056", "clpid": "Liu-Honglin" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In turbid media such as biological tissues, light undergoes multiple scattering. Consequently, it is not possible to focus light at depths beyond one transport mean free path in such media. To break through this limit, we proposed and experimentally demonstrated a novel technique, based on ultrasonic encoding of diffused laser light and optical time reversal, which effectively focuses light into a turbid medium. In the experimental implementation of the Time-Reversed Ultrasonically Encoded (TRUE) optical focusing, a turbid medium was illuminated by a laser beam with a long coherence length. The incident light was multiply scattered inside the medium and ultrasonically encoded within the ultrasonic focal zone. The wavefront of the ultrasonically encoded light was then time reversed by a Phase Conjugate Mirror (PCM) outside the medium. The time-reversed (or phase conjugated) optical wavefront traced back the trajectories of the ultrasonically encoded diffused light, and converged to the ultrasonic focal zone. With a commercially available photorefractive crystal as the PCM, the main approaches for increasing focusing depth are to improve the efficiencies of ultrasonic encoding and time reversal. Our recent experiments showed that light can be focused into a 5-mm thick tissue-mimicking phantom (optical thickness = 50, i.e., geometric thickness = 50 mean free paths) with a dynamically adjustable focus. The TRUE optical focusing opens a door to focusing light into turbid media or manipulating light-matter interactions.", "doi": "10.1117/12.876956", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-18", "pages": "Art. No. 78991A" }, { "id": "authors:8vqr2-vty49", "collection": "authors", "collection_id": "8vqr2-vty49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934251", "type": "book_section", "title": "Chronic label-free volumetric photoacoustic microscopy of melanoma cells in scaffolds in vitro", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Zhang", "given_name": "Yu", "orcid": "0000-0001-8938-1927", "clpid": "Zhang-Yu" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Choi", "given_name": "Sung-Wook", "clpid": "Choi-Sung-Wook" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Visualizing cells in three-dimensional (3D) scaffolds has been one of the major challenges in tissue engineering. Current imaging modalities have limitations. Microscopy, including confocal microscopy, cannot penetrate deeply (> 300 \u03bcm) into the scaffolds; X-ray micro-computed tomography (micro-CT) requires staining of the structure with a toxic agent such as osmium tetroxide. Here, we demonstrate photoacoustic microscopy (PAM) of the spatial distribution and temporal proliferation of melanoma cells inside three-dimensionally porous scaffolds with thicknesses over 1 mm. Melanoma cells have a strong intrinsic contrast which is easily imaged by label-free PAM with high sensitivity. Spatial distributions of the cells in the scaffold were well-resolved in PAM images. Moreover, we chronically imaged the same cell/scaffold constructs at different time points over 2 weeks. The number of cells in the scaffold was quantitatively measured from the PAM volumetric information. The cell proliferation profile obtained from PAM correlated well with that obtained using the traditional 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. We believe that PAM will become a useful imaging modality for tissue engineering applications, especially when thick scaffold constructs are involved, and that this modality can also be extended to image other cell types labeled with contrast agents.", "doi": "10.1117/12.873226", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-18", "pages": "Art. No. 789926" }, { "id": "authors:majj6-jz289", "collection": "authors", "collection_id": "majj6-jz289", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934526", "type": "book_section", "title": "High speed, inverted optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Danielli", "given_name": "Amos", "clpid": "Danielli-A" }, { "family_name": "Chen", "given_name": "Ruiming", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic microscopy (PAM) offers label-free, optical absorption contrast. A high-speed, high-resolution PAM system in an inverted microscope configuration with a laser pulse repetition rate of 100,000 Hz and a stationary ultrasonic transducer was built. Four-dimensional in vivo imaging of microcirculation in mouse skin was achieved at 18 three-dimensional volumes per second with repeated two-dimensional raster scans of 100 by 50 points. The corresponding twodimensional B-scan (50 A-lines) frame rate was 1800 Hz, and the one-dimensional A-scan rate was 90,000 Hz. The lateral resolution is 0.23\u00b10.03 \u03bcm for Au nano-wire imaging, which is 2.0 times below the diffraction limit.", "doi": "10.1117/12.873568", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-18", "pages": "Art. No. 78990T" }, { "id": "authors:gg926-n1e15", "collection": "authors", "collection_id": "gg926-n1e15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933628", "type": "book_section", "title": "Photoacoustic tomography of water in biological tissue", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Xu", "given_name": "Zhun", "clpid": "Xu-Zhun" }, { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "As an emerging imaging technique that combines high optical contrast and ultrasonic detection, photoacoustic tomography (PAT) has been widely used to image optically absorptive objects in both human and animal tissues. PAT overcomes the depth limitation of other high-resolution optical imaging methods, and it is also free from speckle artifacts. To our knowledge, water has never been imaged by PAT in biological tissue. Here, for the first time, we experimentally imaged water in both tissue phantoms and biological tissues using a near infrared (NIR) light source. The differences among photoacoustic images of water with different concentrations indicate that laser-based PAT can usefully detect and image water content in tissue.", "doi": "10.1117/12.873415", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 789912" }, { "id": "authors:h8xme-kkk37", "collection": "authors", "collection_id": "h8xme-kkk37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933346", "type": "book_section", "title": "Development of real-time photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Wang", "given_name": "Lidai", "clpid": "Wang-Lidai" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography detecting ultrasound signals generated from photon absorption provides optical absorption contrast in vivo for structural, functional and molecular imaging. Although photoacoustic tomography technology has grown fast in recent years, real-time photoacoustic imaging with cellular spatial resolution are still strongly demanded. We developed a photoacoustic microscopy which has video-rate imaging capability with cellular spatial resolution. The system consists of a single-element focused ultrasound transducer, a fiber-based light-delivery subsystem, a voice-coil translation stage, a motion controller, and a data acquisition subsystem. A compact cube is employed to split optical and acoustic beams. The mass of the entire scanning photoacoustic probe is less than 40 grams, which minimizes potential vibrations and inertial effects, therefore, makes it capable to scan fast. The imaging system is capable of acquiring 20 cross-sectional (B-scan) images per second over 9 mm, and up to 40 B-scan images per second over 1 mm. Focused laser beams provide a lateral resolution of five microns. Confocal deployment of optical and acoustic focuses provides higher SNR than optical scanning approach. Micron-sized carbon particles flowing in silicone tubing and in vivo blood flows were imaged in video-rate, which demonstrated the capability to image highly dynamic biological processes in vivo with cellular resolution. This real-time high-resolution photoacoustic imaging system provides a promising approach for various in vivo imaging and quantitative studies.", "doi": "10.1117/12.875415", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990R" }, { "id": "authors:p5b12-crf72", "collection": "authors", "collection_id": "p5b12-crf72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934084", "type": "book_section", "title": "Volumetric photoacoustic endoscopy of upper gastrointestinal tract: ultrasonic transducer technology development", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have successfully implemented a focused ultrasonic transducer for photoacoustic endoscopy. The photoacoustic endoscopic probe's ultrasound transducer determines the lateral resolution of the system. By using a focused ultrasonic transducer, we significantly improved the endoscope's spatial resolution and signal-to-noise ratio. This paper describes the technical details of the ultrasonic transducer incorporated into the photoacoustic endoscopic probe and the experimental results from which the transducer's resolution is quantified and the image improvement is validated.", "doi": "10.1117/12.875377", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990D" }, { "id": "authors:5z06c-3rg37", "collection": "authors", "collection_id": "5z06c-3rg37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933801", "type": "book_section", "title": "Subwavelength-resolution photoacoustic microscopy for label-free detection of optical absorption in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Zhang", "given_name": "Chi", "orcid": "0000-0002-1324-2311", "clpid": "Zhang-Chi" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Mainstream optical microscopy technologies normally detect fluorescence or scattering, which may require undesirable labeling, but cannot directly sense optical absorption, which provides essential biological functional information. Here we reported in vivo and label-free subwavelength-resolution photoacoustic microscopy (SW-PAM) by using a waterimmersion optical objective with a 1.23 NA. Capable of detecting nonfluorescent endogenous pigments, SW-PAM provides exquisitely high optical-absorption contrast. And, as a result of background-free detection, the sensitivity of SW-PAM to optical absorption reaches 100%. SW-PAM was demonstrated with wide-field optical microscopy by imaging gold nanospheres, ex vivo cells, and in vivo vasculature and melanoma. It was shown that SW-PAM has approached the ultimate diffraction-limited optical resolution-220 nm resolution at 532 nm wavelength. Subcellular organelles, such as melanosomes, can be resolved by SW-PAM. Vasculature and early-stage melanoma were imaged with 21:1 and 34:1 contrasts, respectively, without labeling. For all these applications, SW-PAM has contrasts orders of magnitude higher than wide-field optical microscopy. Therefore, SW-PAM is expected to join the mainstream microscopy technologies.", "doi": "10.1117/12.873225", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990L" }, { "id": "authors:mqg4h-bst13", "collection": "authors", "collection_id": "mqg4h-bst13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933996", "type": "book_section", "title": "Small-animal whole-body imaging using a photoacoustic full-ring array system", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Xia", "given_name": "Jun", "clpid": "Xia-Jun" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this report, we present a novel 3D photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring transducer array, received photoacoustic signals primarily from a 2-mm-thick slice. The light was generated by a pulse laser, and can either illuminate from the top or be reshaped to illuminate the sample from the side, using a conical lens and an optical condenser. The PACT system was capable of acquiring an in-plane image in 1.6 s; by scanning the sample in the elevational direction, a 3D tomographic image could be constructed. We tested the system by imaging a cylindrical phantom made of human hairs immersed in a scattering medium. The reconstructed image achieved an in-plane resolution of 0.1 mm and an elevational resolution of 1 mm. After deconvolution in the elevational direction, the 3D image was found to match well with the phantom. The system was also used to image a baby mouse in situ; the spinal cord and ribs can be seen easily in the reconstructed image. Our results demonstrate that the PACT system has the potential to be used for fast small-animal whole-body tomographic imaging.", "doi": "10.1117/12.873401", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 789911" }, { "id": "authors:cn439-pdg25", "collection": "authors", "collection_id": "cn439-pdg25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933714", "type": "book_section", "title": "Three-dimensional photoacoustic imaging with a clinical two-dimensional matrix ultrasound transducer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Robert", "given_name": "Jean-Luc", "clpid": "Robert-J-L" }, { "family_name": "David", "given_name": "Guillaume", "clpid": "David-G" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography provides both structural and functional imaging in vivo based on optical absorption contrast. A novel imaging system that incorporates a two-dimensional matrix ultrasound probe for combined photoacoustic and ultrasonic three-dimensional (3D) volumetric imaging is presented. The system consists of a tunable dye laser pumped by a Nd:YAG laser, a commercial ultrasound imaging system (Philips iU22) with a two-dimensional matrix transducer (Philips X7-2, 2500 elements, 2-7 MHz), and a multichannel data acquisition system which allows us to acquire RF channel data. Compared with alternative 3D techniques, this system is attractive because it can generate co-registered 3D photoacoustic and ultrasound images without mechanical scanning. Moreover, the lateral resolution along the azimuth and elevational directions are measured to be 0.77 \u00b1 0.06 mm and 0.96 \u00b1 0.06 mm, respectively, based on reconstructed photoacoustic images of phantoms containing individual human hairs. Finally, in vivo 3D photoacoustic sentinel lymph node mapping using methylene blue dye in a rat model is demonstrated.", "doi": "10.1117/12.875169", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990A" }, { "id": "authors:w4mnc-cnc27", "collection": "authors", "collection_id": "w4mnc-cnc27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933539", "type": "book_section", "title": "Quantification of optical absorption coefficients from acoustic spectra with photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical absorption is closely associated with many physiologically important parameters, such as the concentration and oxygen saturation of hemoglobin, and it can be used to quantify the concentrations of non-fluorescent molecules. We introduce a method to quantify the absolute optical absorption based upon the acoustic spectra of photoacoustic (PA) signals. This method is self-calibrating and thus insensitive to variations in optical fluence. Factors such as the detection system bandwidth and acoustic attenuation can affect the quantification but can be canceled by measuring the acoustic spectra at two optical wavelengths. This method has been implemented on various PA systems, including optical-resolution PA microscopy, acoustic-resolution PA microscopy, and reconstruction based PA array systems. We quantified the optical absorption coefficients of phantom samples at various wavelengths. We also quantified the oxygen saturation of hemoglobin in live mice.", "doi": "10.1117/12.875015", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990W" }, { "id": "authors:5nw1m-0rh66", "collection": "authors", "collection_id": "5nw1m-0rh66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934333", "type": "book_section", "title": "Integrated photoacoustic and fluorescence confocal microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical-resolution photoacoustic microscopy has demonstrated utility in imaging and characterizing microvasculature networks in vivo. This work presents a novel imaging system that integrates optical-resolution photoacoustic microscopy and fluorescence confocal microscopy for simultaneous photoacoustic and fluorescence imaging. The integrated system can acquire intrinsically registered photoacoustic and fluorescence images in a single scan. Capable of providing micrometer scale microscopic imaging of both optical absorption and fluorescence contrasts, the system demonstrates in vivo imaging of oxygen saturation and oxygen partial pressure in mouse ears.", "doi": "10.1117/12.874888", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990M" }, { "id": "authors:t4v6b-tey24", "collection": "authors", "collection_id": "t4v6b-tey24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934171", "type": "book_section", "title": "Noninvasive quantification of metabolic rate of oxygen (MRO_2) by photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Many diseases, normal decay and physiological functions are closely related to alterations in the metabolic rate of oxygen (MRO_2). In this study, we demonstrate that all the parameters for MRO_2 quantification can be simultaneously obtained by optical-resolution photoacoustic microscopy (OR-PAM). MRO_2 of the mouse ear under normothermia (31 \u00b0C skin temperature) and controlled systematic hyperthermia (42 \u00b0C skin temperature) was studied. As a result of hyperthermia, the MRO_2 increased by 34.1%. The tumor hypermetabolism was also demonstrated by longitudinally monitoring a melanoma growing on a mouse ear. The results show that OR-PAM, as a single noninvasive imaging modality, is well suited for quantitative MRO_2 measurement in microenvironments.", "doi": "10.1117/12.874777", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990N" }, { "id": "authors:qwg69-80q07", "collection": "authors", "collection_id": "qwg69-80q07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130933882", "type": "book_section", "title": "Photoacoustic image-guided needle biopsy of sentinel lymph nodes", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Akers", "given_name": "Walter J.", "clpid": "Akers-W-J" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Song", "given_name": "Liang", "clpid": "Song-Liang" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Margenthaler", "given_name": "Julie A.", "clpid": "Margenthaler-J-A" }, { "family_name": "Achilefu", "given_name": "Samuel", "clpid": "Achilefu-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have implemented a hand-held photoacoustic and ultrasound probe for image-guided needle biopsy using a modified clinical ultrasound array system. Pulsed laser light was delivered via bifurcated optical fiber bundles integrated with the hand-held ultrasound probe. We photoacoustically guided needle insertion into rat sentinel lymph nodes (SLNs) following accumulation of indocyanine green (ICG). Strong photoacoustic image contrast of the needle was achieved. After intradermal injection of ICG in the left forepaw, deeply positioned SLNs (beneath 2-cm thick chicken breast) were easily indentified in vivo and in real time. Further, we confirmed ICG uptake in axillary lymph nodes with in vivo and ex vivo fluorescence imaging. These results demonstrate the clinical potential of this hand-held photoacoustic system for facile identification and needle biopsy of SLNs for cancer staging and metastasis detection in humans.", "doi": "10.1117/12.874956", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78990K" }, { "id": "authors:yvk00-1tg91", "collection": "authors", "collection_id": "yvk00-1tg91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-130934416", "type": "book_section", "title": "Tyrosinase-catalyzed melanin as a contrast agent for photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Krumholz", "given_name": "Arie", "clpid": "Krumholz-A" }, { "family_name": "Chavez", "given_name": "Sarah", "clpid": "Chavez-S" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Fleming", "given_name": "Timothy", "clpid": "Fleming-T-P" }, { "family_name": "Gillanders", "given_name": "William E.", "clpid": "Gillanders-W-E" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "It is difficult to distinguish between tumor cells and surrounding cells without staining as is done in histology. We developed tyrosinase-catalyzed melanin as a reporter gene for photoacoustic tomography. Tyrosinase is the primary enzyme responsible for the production of melanin and alone is sufficient to produce melanin in non-melanogenic cells. Two cell lines were created: a stably transfected HeLa line and a transiently transfected 293 line. A phantom experiment was performed with the 293 transfected cells 48 hours post transfection and the results compared with oxygenated whole blood, B16 melanoma and 293 control cells. An in vivo experiment was performed using the transfected HeLa cells xenografted into a nude mouse ear, and then imaged. The results show strong contrast for tyrosinase-catalyzed melanin in both the 293 cells in the tube phantom as well as the in vivo result showing melanin in a nude mouse ear. Transfection increased expression in 293 cells 159 fold and image contrast compared to blood by as much as 50 fold. Due to the strong signal obtained at longer wavelengths and the decrease of blood signal at the same wavelengths, tyrosinase catalyzed melanin is a good candidate as a molecular imaging contrast agent for photoacoustic tomography.", "doi": "10.1117/12.879110", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-17", "pages": "Art. No. 78991G" }, { "id": "authors:k7wdw-h5h36", "collection": "authors", "collection_id": "k7wdw-h5h36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180920-132554582", "type": "book_section", "title": "Optical-resolution photoacoustic microscopy of ischemic stroke", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2011", "author": [ { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Gonzales", "given_name": "Ernie", "clpid": "Gonzales-E" }, { "family_name": "Soetikno", "given_name": "Brian", "clpid": "Soetikno-B" }, { "family_name": "Gong", "given_name": "Enhao", "clpid": "Gong-Enhao" }, { "family_name": "Yan", "given_name": "Ping", "clpid": "Yan-Ping" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Lee", "given_name": "Jin-Moo", "clpid": "Lee-Jin-Moo" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A major obstacle in understanding the mechanism of ischemic stroke is the lack of a tool to noninvasively or minimally invasively monitor cerebral hemodynamics longitudinally. Here, we applied optical-resolution photoacoustic microscopy (OR-PAM) to longitudinally study ischemic stroke induced brain injury in a mouse model with transient middle cerebral artery occlusion (MCAO). OR-PAM showed that, during MCAO, the average hemoglobin oxygen saturation (sO2) values of feeder arteries and draining veins within the stroke core region dropped ~10% and ~34%, respectively. After reperfusion, arterial sO_2 recovered back to the baseline; however, the venous sO_2 increased above the baseline value by ~7%. Thereafter, venous sO_2 values were close to the arterial sO_2 values, suggesting eventual brain tissue infarction.", "doi": "10.1117/12.874366", "isbn": "9780819484369", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2011-02-10", "pages": "Art. No. 789906" }, { "id": "authors:vqwbx-csv91", "collection": "authors", "collection_id": "vqwbx-csv91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708286", "type": "book_section", "title": "Molecular photoacoustic imaging using gold nanoparticles as a contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Cho", "given_name": "Eun Chul", "clpid": "Cho-Eun-Chul" }, { "family_name": "Chen", "given_name": "Jingyi", "clpid": "Chen-Jingyi" }, { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Au", "given_name": "Leslie", "clpid": "Au-Leslie" }, { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Zhang", "given_name": "Qiang", "orcid": "0000-0002-8376-131X", "clpid": "Zhang-Qiang" }, { "family_name": "Cobley", "given_name": "Claire M.", "clpid": "Cobley-C-M" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Gold nanoparticles have received much attention due to their potential diagnostic and therapeutic applications. Gold nanoparticles are attractive in many biomedical applications because of their biocompatibility, easily modifiable surfaces for targeting, lack of heavy metal toxicity, wide range of sizes (35-100 nm), tunable plasmonic resonance peak, encapsulated site-specific drug delivery, and strong optical absorption in the near-infrared regime. Specifically, due to their strong optical absorption, gold nanoparticles have been used as a contrast agent for molecular photoacoustic (PA) imaging of tumor. The plasmonic resonance peak of the gold nanocages (AuNCs) was tuned to the near-infrared region, and the ratio of the absorption cross-section to the extinction cross-section was approximately ~70%, as measured by PA sensing. We used PEGylated gold nanocages (PEG-AuNCs) as a passive targeting contrast agent on melanomas. After 6-h intravenous injection of PEG-AuNCs, PA amplitude was increased by ~14 %. These results strongly suggest PA imaging paired with AuNCs is a promising diagnostic tool for early cancer detection.", "doi": "10.1117/12.843549", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-25", "pages": "Art. No. 75641V" }, { "id": "authors:gg1kq-ydf03", "collection": "authors", "collection_id": "gg1kq-ydf03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708965", "type": "book_section", "title": "In vivo dual-modality imaging of lymphatic systems using indocyanine green in rats: three-dimensional photoacoustic imaging and planar fluorescence imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The purpose of this study is to map non-invasively sentinel lymph nodes (SLNs) and lymphatic vessels of rats in vivo using FDA-approved indocyanine green (ICG) and two non-ionizing imaging modalities: volumetric spectroscopic photoacoustic (PA) imaging, which measures optical absorption, and planar fluorescence imaging, which measures fluorescent emission. SLNs and lymphatic vessels were clearly visible after a 0.2 ml-intradermal-injection of 1 mM ICG in both imaging systems. We also imaged deeply positioned lymph nodes in vivo by layering biological tissues on top of rats. These two modalities, when used together with ICG, have the potential to map SLNs in axillary staging and to study tumor metastasis in breast cancer patients.", "doi": "10.1117/12.841964", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75642W" }, { "id": "authors:9j4ps-fn383", "collection": "authors", "collection_id": "9j4ps-fn383", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709052", "type": "book_section", "title": "Tissue temperature monitoring using thermoacoustic and photoacoustic techniques", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Pramanik", "given_name": "Manojit", "clpid": "Pramanik-M" }, { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Real-time temperature monitoring with high spatial resolution (~1 mm) and high temperature sensitivity (1 \u00b0C or better) is needed for the safe deposition of heat energy in surrounding healthy tissue and efficient destruction of tumor and abnormal cells during thermotherapy. A temperature sensing technique using thermoacoustic and photoacoustic measurements combined with a clinical Philips ultrasound imaging system (iU22) has been explored in this study. Using a tissue phantom, this noninvasive method has been demonstrated to have high temporal resolution and temperature sensitivity. Because both photoacoustic and thermoacoustic signal amplitudes depend on the temperature of the source object, the signal amplitudes can be used to monitor the temperature. The signal is proportional to the dimensionless Grueneisen parameter of the object, which in turn varies with the temperature of the object. A temperature sensitivity of 0.5 \u00b0C was obtained at a temporal resolution as short as 3.6 s with 50 signal averages.", "doi": "10.1117/12.842139", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75641Y" }, { "id": "authors:wrdgc-rvh22", "collection": "authors", "collection_id": "wrdgc-rvh22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708875", "type": "book_section", "title": "Real-time monitoring of small animal cortical hemodynamics by photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Aquirre", "given_name": "Andres", "clpid": "Aquirre-A" }, { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "For the first time, the hemodynamics within the entire cerebral cortex of a mouse were studied by using photoacoustic tomography (PAT) non-invasively and in real time. The PAT system, based on a 512-element full-ring array with cylindrical focusing, received the PA signal primarily from a slice of about 2 mm thickness. This system can provide not only high resolution brain vasculature images but also hemodynamic functional images. We recorded the wash-in process of a photoacoustic contrast agent in a mouse brain in real time. Our results demonstrated that PAT is a powerful imaging modality to study real-time small animal neurofunctional activities that cause changes in hemodynamics.", "doi": "10.1117/12.842159", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756427" }, { "id": "authors:tmm6h-2jj31", "collection": "authors", "collection_id": "tmm6h-2jj31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708684", "type": "book_section", "title": "Photoacoustic microscopy using Evans Blue dye as a contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong", "clpid": "Wang-Lihong-V" } ], "abstract": "Complete and continuous imaging of microvascular networks is crucial for a wide variety of biomedical applications. Photoacoustic tomography can provide high resolution microvascular imaging using hemoglobin within red blood cells (RBC) as an endogenous contrast agent. However, intermittent RBC flow in capillaries results in discontinuous and fragmentary capillary images. To overcome this problem, we used Evans Blue (EB) dye as a contrast agent for in vivo photoacoustic imaging. EB has strong optical absorption at 610 nm and distributes uniformly in the blood stream by chemically binding to albumin. By intravenous injection of EB (6%, 200 \u03bcL), complete and continuous microvascular networks-especially capillaries-of the ears of nude mice were imaged. The diffusion of EB (3%, 100 \u03bcL) leaving the blood stream was monitored for 2 hours. At lower administration dose of EB (3%, 50 \u03bcL), the clearance of the EB-albumin complex was imaged for 10 days and quantitatively investigated using a two-compartment model.", "doi": "10.1117/12.840684", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75642J" }, { "id": "authors:94te1-bft52", "collection": "authors", "collection_id": "94te1-bft52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708773", "type": "book_section", "title": "Photoacoustic quantification of the optical absorption cross-sections of gold nanostructures", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Cho", "given_name": "Eun Chul", "clpid": "Cho-Eun-Chul" }, { "family_name": "Zhou", "given_name": "Fei", "clpid": "Zhou-Fei" }, { "family_name": "Cobley", "given_name": "Claire M.", "clpid": "Cobley-C-M" }, { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Chen", "given_name": "Jingyi", "clpid": "Chen-Jingyi" }, { "family_name": "Li", "given_name": "Zhi-Yuhan", "clpid": "Li-Zhi-Yuhan" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "This study demonstrates a method for measuring the optical absorption cross-sections (\u03c3_a) of Au-Ag nanocages and Au nanorods using photoacoustic (PA) sensing. PA signals are directly proportional to the absorption coefficient (\u03bc_a) of the nanostructure. For each type of nanostructure, we first obtained \u03bca from the PA signal by benchmarking against a linear calibration curve (PA signal vs. \u03bc_a) derived from a set of methylene blue solutions with different concentrations. We then calculated \u03c3_a by dividing the \u03bc_a by the corresponding concentration of the Au nanostructure. Additionally, we obtained the extinction cross-section (\u03c3_e, sum of absorption and scattering cross-sections) from the extinction spectrum recorded using a conventional UV-vis-NIR spectrometer. From the measurements of \u03c3_a and \u03c3_e, we were able to easily derive both the absorption and scattering cross-sections for each type of gold nanostructure. This method can potentially provide the optical absorption and scattering properties of gold nanostructures and other types of nanomaterials.", "doi": "10.1117/12.843554", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756430" }, { "id": "authors:wwrkf-m0x94", "collection": "authors", "collection_id": "wwrkf-m0x94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708416", "type": "book_section", "title": "Photoacoustic tomography of foreign bodies in soft biological tissue", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Cai", "given_name": "Xin", "clpid": "Cai-Xin" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Pramanik", "given_name": "Manojit", "clpid": "Pramanik-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound imaging suffers from poor sensitivity (~50%) and specificity in detecting small foreign bodies in tissue. Hence, alternative imaging methods are needed. Photoacoustic (PA) imaging takes advantage of strong optical absorption contrast and high ultrasonic resolution. This work employed a PA imaging system to detect foreign bodies in biological tissues. To achieve deep penetration, we used near-infrared light and a 5-MHz spherically focused ultrasonic transducer. PA images were obtained from objects (glass, wood, cloth, plastic, and metal) embedded in chicken tissue. The location and size of the targets from the PA images agreed well with those of the actual samples. Objects were imaged more than 1 cm deep. Spectroscopic PA imaging was also performed on the objects. These results suggest PA imaging can potentially be a useful intraoperative imaging tool to identify foreign bodies and discriminate viable tissues in wounded patients.", "doi": "10.1117/12.845942", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75643H" }, { "id": "authors:qpz1x-anw88", "collection": "authors", "collection_id": "qpz1x-anw88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039326", "type": "book_section", "title": "Optical-resolution photoacoustic microscopy of angiogenesis in a transgenic mouse model", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Oladipupo", "given_name": "Sunday", "orcid": "0000-0001-6555-0693", "clpid": "Oladipupo-Sunday-S" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Santeford", "given_name": "Andrea C.", "clpid": "Santeford-Andrea-C" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-Konstantin-I" }, { "family_name": "Kovalski", "given_name": "Joanna", "clpid": "Kovalski-Joanna-R" }, { "family_name": "Arbeit", "given_name": "Jeffrey M.", "clpid": "Arbeit-Jeffrey-M" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A major obstacle in studying angiogenesis is the inability to noninvasively image neovascular development in an individual animal. We applied optical-resolution photoacoustic microscopy (OR-PAM) to determine the kinetics of hypoxia-inducible factor-1 (HIF-1)-mediated angiogenesis in a transgenic mouse model. During continuous 30-day activation of HIF-1\u03b1, we used OR-PAM to monitor alterations in microvasculature in transgenic mice compared to nontransgenic mice. OR-PAM has demonstrated the potential to precisely monitor antiangiogenic therapy of human cancers, allowing for rapid determinations of therapeutic efficacy or resistance.", "doi": "10.1117/12.841177", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756406" }, { "id": "authors:mh60k-bjr47", "collection": "authors", "collection_id": "mh60k-bjr47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039418", "type": "book_section", "title": "In vivo photoacoustic and ultrasonic mapping of rat sentinel lymph nodes with a modified commercial ultrasound imaging system", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Erpelding", "given_name": "Todd N.", "clpid": "Erpelding-T-N" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Pramanik", "given_name": "Manojit", "clpid": "Pramanik-M" }, { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Dean", "given_name": "John", "clpid": "Dean-J" }, { "family_name": "Jankovic", "given_name": "Ladislav", "clpid": "Jankovic-L" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Sentinel lymph node biopsy (SLNB) has become the standard method for axillary staging in breast cancer patients, relying on invasive identification of sentinel lymph nodes (SLNs) following injection of blue dye and radioactive tracers. While SLNB achieves a low false negative rate (5-10%), it is an invasive procedure requiring ionizing radiation. As an alternative to SLNB, ultrasound-guided fine needle aspiration biopsy has been tested clinically. However, ultrasound alone is unable to accurately identify which lymph nodes are sentinel. Therefore, a non-ionizing and noninvasive detection method for accurate SLN mapping is needed. In this study, we successfully imaged methylene blue dye accumulation in vivo in rat axillary lymph nodes using a Phillips iU22 ultrasound imaging system adapted for photoacoustic imaging with an Nd:YAG pumped, tunable dye laser. Photoacoustic images of rat SLNs clearly identify methylene blue dye accumulation within minutes following intradermal dye injection and co-registered photoacoustic/ultrasound images illustrate lymph node position relative to surrounding anatomy. To investigate clinical translation, the imaging depth was extended up to 2.5 cm by adding chicken breast tissue on top of the rat skin surface. These results raise confidence that photoacoustic imaging can be used clinically for accurate, noninvasive SLN mapping.", "doi": "10.1117/12.841858", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756418" }, { "id": "authors:7x5rp-p1b80", "collection": "authors", "collection_id": "7x5rp-p1b80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039229", "type": "book_section", "title": "Transverse flow measurement using photoacoustic Doppler bandwidth broadening: phantom and in vivo studies", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In photoacoustic (PA) imaging of microvascular networks, the transverse component of the blood flow that is perpendicular to the acoustic probing beam is usually dominant. We propose a new method to measure the transverse flow, based on the Doppler bandwidth broadening. The bandwidth broadening is inversely proportional to the transit time spent by the absorbers passing through the focus. Because the photoacoustic signal in one A-scan has a wide band, multiple successive A-scans are used to estimate the relatively small signal variance. Then the bandwidth broadening can be calculated from the standard derivation of the Doppler spectrum. By exploiting the pulse excitation and bidirectional raster motor scanning, threedimensional structural and flow information can be obtained simultaneously. From a flow of a suspension of carbon particles (diameter: 6 \u03bcm), transverse flow speeds from 0 to 2.5 mm/s were measured using optical-resolution photoacoustic microscopy. The bandwidth broadening at each speed was in good agreement with the theoretical prediction. The blood flow in a mouse brain was also imaged.", "doi": "10.1117/12.840676", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756402" }, { "id": "authors:z2etq-93t54", "collection": "authors", "collection_id": "z2etq-93t54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039616", "type": "book_section", "title": "Invasive and transcranial photoacoustic imaging of the vascular response to brain electrical stimulation", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Tsytsarev", "given_name": "Vassiliy", "clpid": "Tsytsarev-V" }, { "family_name": "Yao", "given_name": "Junjie", "clpid": "Yao-Junjie" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Favazza", "given_name": "Christopher P.", "clpid": "Favazza-C-P" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Advances in the brain functional imaging greatly facilitated the understanding of neurovascular coupling. For monitoring of the microvascular response to the brain electrical stimulation in vivo we used optical-resolution photoacoustic microscopy (OR-PAM) through the cranial openings as well as transcranially. Both types of the vascular response, vasoconstriction and vasodilatation, were clearly observed with good spatial and temporal resolution. Obtained results confirm one of the primary points of the neurovascular coupling theory that blood vessels could present vasoconstriction or vasodilatation in response to electrical stimulation, depending on the balance between inhibition and excitation of the different parts of the elements of the neurovascular coupling system.", "doi": "10.1117/12.840290", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756407" }, { "id": "authors:ydj2a-0h915", "collection": "authors", "collection_id": "ydj2a-0h915", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140709139", "type": "book_section", "title": "Fast-scanning reflection-mode integrated photoacoustic and optical-coherence microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We previously demonstrated that multimodal microscopy combining photoacoustic microscopy and optical coherence tomography can provide comprehensive insight into biological tissue at \u03bcm-level resolution by exploiting both optical absorption and scattering contrasts. Recently, we have developed a second-generation integrated photoacoustic and optical-coherence microscope, which can potentially be adapted for clinical applications. In this new system, we can perform photoacoustic and optical-coherence imaging simultaneously at a speed of 5,000 A-lines per second with real-time on-screen display. Also, both modalities now work in reflection mode instead of transmission mode, allowing easy access to various anatomical locations of interest. Imaging of skin and eye has been demonstrated in living small animals.", "doi": "10.1117/12.843826", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75641Z" }, { "id": "authors:hk1b8-s4a83", "collection": "authors", "collection_id": "hk1b8-s4a83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039051", "type": "book_section", "title": "In vivo functional human imaging using photoacoustic microscopy: response to ischemic and thermal stimuli", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Favazza", "given_name": "Christopher", "clpid": "Favazza-C-P" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Cornelius", "given_name": "Lynn", "clpid": "Cornelius-L-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report results of two in vivo functional human imaging experiments using photoacoustic microscopy. In Experiment 1, the hemodynamic response to an ischemic event was measured. The palm of a volunteer was imaged and a single cross-section was monitored while periodic arterial occlusions were administered using a blood pressure cuff wrapped around the upper arm and inflated to ~280 mmHg. Significant relative decreases in oxygen saturation (sO_2) and total hemoglobin (HbT) were observed during periods of ischemia. Upon release of the occlusion, significant relative increases in sO_2 and HbT due to post-occlusive reactive hyperemia were recorded. Experiment 2 explored the vascular response to a local, external thermal stimulus. Thermal hyperemia is a common physiological phenomenon and thermoregulation function in which blood flow to the skin is increased to more efficiently exchange heat with the ambient environment. The forearm of a volunteer was imaged and a single cross-section was monitored while the imaged surface was exposed to an elevated temperature of ~46\u00b0C. Due to thermal hyperemia, relative increases in sO_2 and HbT were measured as the temperature of the surface was raised. These results may contribute as clinically relevant measures of vascular functioning for detection and assessment of vascular related diseases.", "doi": "10.1117/12.841975", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75640Z" }, { "id": "authors:j7hsz-1yj72", "collection": "authors", "collection_id": "j7hsz-1yj72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708592", "type": "book_section", "title": "In vivo, label-free photoacoustic microscopy of the anterior segment of the mouse eye", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Rao", "given_name": "Bin", "orcid": "0000-0001-6494-3110", "clpid": "Rao-Bin" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Both iris fluorescein angiography (IFA) and indocyanine green angiography (ICGA) provide ophthalmologists imaging tools in studying the microvasculature structure and hemodynamics of the anterior segment of the eye in normal and diseased status. However, a non-invasive, endogenous imaging modality is preferable for the monitoring of hemodynamics of the iris microvasculature. We investigated the in vivo, label-free ocular anterior segment imaging with photo-acoustic microscopy (PAM) in mouse eyes. We demonstrated the unique advantage of endogenous contrast that is not available in both IFA and ICGA. The laser radiation was maintained within the ANSI laser safety limit. The in vivo, label-free nature of our imaging technology has the potential for ophthalmic applications.", "doi": "10.1117/12.843052", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75643E" }, { "id": "authors:jcr8g-1bs45", "collection": "authors", "collection_id": "jcr8g-1bs45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039145", "type": "book_section", "title": "Photoacoustic microscopy with submicron resolution", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We show that it is possible to obtain high optical contrast photoacoustic images of tissue with 0.55 \u03bcm transverse resolution. To achieve high sensitivity, we used a high NA (0.85), 125 MHz spherically focused ultrasonic transducer in a confocal arrangement with a high resolution optical objective (NA=0.6). Laser pulses of a few nJ in pulse energy with durations of 1.5 ns at a 20 KHz pulse repetition rate were used to generate photoacoustic waves. Although the penetration depth is limited to hundreds of microns by both optical scattering and ultrasonic absorption, the developed technique can compete with optical microscopy, for example, in quantitative spectral measurements, in microcirculation research, or in nanoparticle detection.", "doi": "10.1117/12.841919", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75640W" }, { "id": "authors:jnw23-8zn04", "collection": "authors", "collection_id": "jnw23-8zn04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160038970", "type": "book_section", "title": "Ultrasound array photoacoustic microscopy for dynamic in vivo 3D imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Song", "given_name": "Liang", "clpid": "Song-Liang" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Using realtime ultrasound array photoacoustic microscopy (UA-PAM), we demonstrated the feasibility of noninvasive in vivo imaging of human pulsatile dynamics, as well as 3-D dynamic imaging of sentinel lymph nodes (SLNs) in a murine model. The system, capable of realtime B-scan imaging at 50 Hz and high-speed 3-D imaging, was validated by imaging the subcutaneous microvasculature in rats and humans. After the validation, a human superficial palmar was imaged, and its pulsatile dynamics monitored, with 20-ms B-scan imaging temporal resolution. In addition, noninvasive photoacoustic sentinel lymph node (SLN) mapping with high spatial resolution has the potential to reduce the false negative rate and eliminate the use of radioactive tracers. Upon intra-dermal injection of Evans blue, the system maps SLNs accurately in mice and rats. Furthermore, the ~6 s 3-D imaging temporal resolution offers the capability to quantitatively and noninvasively monitor the dye dynamics in SLNs in vivo through sequential 3-D imaging. The demonstrated capability suggests that high-speed 3-D photoacoustic imaging should facilitate the understanding of the dynamics of various dyes in SLNs, and potentially help identify SLNs with high accuracy. With the results shown in this study, we believe that UA-PAM can potentially enable many new possibilities for studying functional and physiological dynamics in both preclinical and clinical imaging settings.", "doi": "10.1117/12.840582", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 756403" }, { "id": "authors:2hvy5-xw784", "collection": "authors", "collection_id": "2hvy5-xw784", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180918-140708503", "type": "book_section", "title": "Optical-resolution photoacoustic microscopy of amyloid-\u03b2 deposits in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Yan", "given_name": "Ping", "clpid": "Yan-Ping" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Lee", "given_name": "Jin-Moo", "clpid": "Lee-Jin-Moo" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Advances in high-resolution imaging have permitted microscopic observations within the brains of living animals. Applied to Alzheimer's disease (AD) mouse models, multiphoton microscopy has opened a new window to study the real-time appearance and growth of amyloid plaques. Here, we report an alternative technology-optical-resolution photoacoustic microscopy (OR-PAM)-for in vivo imaging of amyloid plaques in a transgenic AD mouse model. In vivo validation using multiphoton microscopy shows that OR-PAM has sufficient sensitivity and spatial resolution to identify amyloid plaques in living brains. In addition, with dual-wavelength OR-PAM, the three-dimensional morphology of amyloid plaques and the surrounding microvasculature are imaged simultaneously through a cranial window. In vivo transcranial OR-PAM imaging of amyloid plaques is highly likely once the imaging parameters are optimized.", "doi": "10.1117/12.843919", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75643D" }, { "id": "authors:kvdbj-q2903", "collection": "authors", "collection_id": "kvdbj-q2903", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160038854", "type": "book_section", "title": "Volumetric photoacoustic endoscopy of internal organs: a phantom and in situ study", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Chen", "given_name": "Ruimin", "orcid": "0000-0002-5338-359X", "clpid": "Chen-Ruimin" }, { "family_name": "Yang", "given_name": "Hao-Chung", "clpid": "Yang-Hao-Chung" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this study, we further developed our photoacoustic endoscopic system to produce three-dimensional images of internal organs by performing pullback C-scans. Employing the side-scanning photoacoustic endoscopic probe discussed in the Optical Society of America's journal Optics Letters, we could acquire successive B-scan images by pulling back the probe with a motorized linear stage. We demonstrate the endoscopic system's volumetric imaging ability through imaging of a metal wire phantom and an in situ rat rectum.", "doi": "10.1117/12.842503", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-23", "pages": "Art. No. 75640D" }, { "id": "authors:25k1y-2dn41", "collection": "authors", "collection_id": "25k1y-2dn41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180919-160039714", "type": "book_section", "title": "Compressed sensing in photoacoustic tomography with in vivo experiments", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2010", "author": [ { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Song", "given_name": "Liang", "clpid": "Song-Liang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The data acquisition speed in photoacoustic computed tomography (PACT) is limited by the laser repetition rate and the number of parallel ultrasound detecting channels. Reconstructing PACT image with a less number of measurements can effectively accelerate the data acquisition and reduce the system cost. Recently emerged Compressed Sensing (CS) theory enables us to reconstruct a compressible image with a small number of projections. This paper adopts the CS theory for reconstruction in PACT. The idea is implemented as a non-linear conjugate gradient descent algorithm and tested with phantom and in vivo experiments.", "doi": "10.1117/12.841311", "isbn": "9780819479600", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2010-02-11", "pages": "Art. No. 75640J" }, { "id": "authors:9gyhj-0hy69", "collection": "authors", "collection_id": "9gyhj-0hy69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905325", "type": "book_section", "title": "Ultrasound-modulated optical microscopy for ex-vivo imaging of scattering biological tissue", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Kothapalli", "given_name": "Sri-Rajasekhar", "clpid": "Kothapalli-S-R" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound-modulated optical microscopy (UOM) based on a long-cavity confocal Fabry-Perot interferometer (CFPI) [J.Biomed.Opt. 13(5), 0504046, (2008)] is used for real time detection of multiply scattered light modulated by high frequency (30 MHz) ultrasound pulses propagating in an optically strongly scattering medium. In this article, we use this microscope to study the dependence of ultrasound-modulated optical signals on the optical absorption of objects embedded about 3 mm deep in tissue mimicking phantoms. These results demonstrate that the dependence is nearly linear. Most importantly, we imaged blood vasculature and melanin in highly scattering tissue samples from a mouse and a rat. Thus UOM can be used to study the morphology of blood vasculature and blood-associated functional parameters, such as oxygen saturation.", "doi": "10.1117/12.810566", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772N" }, { "id": "authors:ef78q-e8186", "collection": "authors", "collection_id": "ef78q-e8186", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906727", "type": "book_section", "title": "In vivo photoacoustic (PA) mapping of sentinel lymph nodes (SLNs) using carbon nanotubes (CNTs) as a contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Pramanik", "given_name": "Manojit", "clpid": "Pramanik-M" }, { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Swierczewska", "given_name": "Magdalena", "clpid": "Swierczewska-M" }, { "family_name": "Green", "given_name": "Danielle", "clpid": "Green-D" }, { "family_name": "Sitharaman", "given_name": "Balaji", "clpid": "Sitharaman-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Sentinel lymph node biopsy (SLNB), a less invasive alternative to axillary lymph node dissection (ALND), is routinely used in clinic for staging breast cancer. In SLNB, lymphatic mapping with radio-labeled sulfur colloid and/or blue dye helps identify the sentinel lymph node (SLN), which is most likely to contain metastatic breast cancer. Even though SLNB, using both methylene blue and radioactive tracers, has a high identification rate, it still relies on an invasive surgical procedure, with associated morbidity. In this study, we have demonstrated a non-invasive single-walled carbon nanotube (SWNT)-enhanced photoacoustic (PA) identification of SLN in a rat model. We have used single-walled carbon nanotubes (SWNTs) as a photoacoustic contrast agent to map non-invasively the sentinel lymph nodes (SLNs) in a rat model in vivo. We were able to identify the SLN non-invasively with high contrast to noise ratio (~90) and high resolution (~500 \u03bcm). Due to the broad photoacoustic spectrum of these nanotubes in the near infrared wavelength window we could easily choose a suitable light wavelength to maximize the imaging depth. Our results suggest that this technology could be a useful clinical tool, allowing clinicians to identify SLNs non-invasively in vivo. In the future, these contrast agents could be functionalized to do molecular photoacoustic imaging.", "doi": "10.1117/12.808522", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71771N" }, { "id": "authors:k9h75-8e738", "collection": "authors", "collection_id": "k9h75-8e738", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905593", "type": "book_section", "title": "Fast 3-D photoacoustic imaging in vivo with a high frequency ultrasound array toward clinical applications", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Song", "given_name": "Liang", "clpid": "Song-Liang" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Bitton", "given_name": "Rachel", "clpid": "Bitton-R" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an in vivo reflection-mode photoacoustic microscopy system that performs B-scan imaging at 50 Hz with realtime beamforming and 3-D imaging of 166 B-scan frames at 1 Hz with post-beamforming. To our knowledge, this speed is currently the fastest in high frequency photoacoustic imaging. In addition, with a custom fiber based light delivery system, the imaging device is capable of performing handheld operation. Software for image processing and display with clinically user-friendly graphic user interface (GUI) is developed. The system has axial, lateral, and elevational resolutions of 25, 70, and 200 \u03bcm, respectively, and can image 3 mm deep in scattering biological tissue. Volumetric images of subcutaneous vasculature in murine are demonstrated in vivo. The system is anticipated to have potential clinical applications in skin melanoma detection due to its unique ability to image in realtime and to image anatomical sites inaccessible to other imaging systems.", "doi": "10.1117/12.809013", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770G" }, { "id": "authors:9w8md-47961", "collection": "authors", "collection_id": "9w8md-47961", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906468", "type": "book_section", "title": "The speckle-free nature of photoacoustic imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Guo", "given_name": "Zijian", "clpid": "Guo-Zijian" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic imaging for biomedical applications has seen significant growth during the past few years. Despite its coherent nature, it possesses a unique advantage to produce images devoid of speckle artifacts. The reason responsible for this salient feature has not been addressed so far. We found this is a direct result of its extraordinary absorption contrast. Our discovery is explained using simulations based on a practical photoacoustic imaging system.", "doi": "10.1117/12.809374", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772J" }, { "id": "authors:9apdf-dqq95", "collection": "authors", "collection_id": "9apdf-dqq95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906829", "type": "book_section", "title": "Ring-shaped light illumination ultrasound-modulated optical tomography and its application for sentinel lymph node mapping ex vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have succeeded in implementing ring-shaped light illumination ultrasound-modulated optical tomography (UOT) in both transmission and reflection modes. These systems used intense acoustic bursts and a charge-coupled device camera-based speckle contrast detection method. By mounting an ultrasound transducer into an optical condenser, we can combine the illuminating light component with the ultrasound transducer. Thus, the UOT system is more clinically applicable than previous orthogonal mode systems. Furthermore, we have successfully imaged an ex vivo methyleneblue-dyed sentinel lymph node (SLN) embedded deeper than 12 mm, the mean depth of human sentinel lymph nodes, in chicken breast tissue. These UOT systems offer several advantages: noninvasiveness, nonionizing radiation, portability, cost-effectiveness, and possibility of combination with ultrasound pulse-echo imaging and photoacoustic imaging. One potential application of the UOT systems is mapping SLNs in axillary staging for breast cancer patients.", "doi": "10.1117/12.808309", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71771F" }, { "id": "authors:0jrz5-w1136", "collection": "authors", "collection_id": "0jrz5-w1136", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905786", "type": "book_section", "title": "Endoscopic photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Yang", "given_name": "Joon-Mo", "clpid": "Yang-Joon-Mo" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Yang", "given_name": "Hao-Chung", "clpid": "Yang-Hao-Chung" }, { "family_name": "Zhou", "given_name": "Qifa", "clpid": "Zhou-Qifa" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a concept and system implementation for endoscopic photoacoustic microscopy that enables minimally invasive diagnosis of internal organs. The system incorporates an in-house made single element ultrasonic transducer for photoacoustic signal detection and an optical fiber for light delivery into a tubular probe with a mechanical scanning unit. The implemented probe size for the distal end is 4.2 mm in diameter and 48 mm in length. We evaluated the system's performance by imaging a carbon fiber in clear and turbid media. We also demonstrated its ability to image actual biological tissues and its endoscopic applicability, by imaging abdominal surfaces and a large intestinal tract of a rat ex vivo. This study shows the system's potential for in vivo optical biopsy of tissue abnormalities, such as tumors, developed in internal organs.", "doi": "10.1117/12.810952", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770N" }, { "id": "authors:k7x9g-tyz28", "collection": "authors", "collection_id": "k7x9g-tyz28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905893", "type": "book_section", "title": "Photoacoustic microscopy of cerebral blood-oxygenation dynamics in mice", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Stein", "given_name": "Erich W.", "clpid": "Stein-E-W" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this work, we exploit the high depth and temporal resolutions of PAM to noninvasively image the blood-oxygenation dynamics of multiple cortex vessels in the mouse brain simultaneously in response to controlled hypoxic and hyperoxic challenges. The dark-field photoacoustic microscopy (PAM) technique was enhanced to image the cortex vasculature of the mouse brain in vivo using endogenous hemoglobin contrast with one second temporal resolution. The maximum values of about 20% with standard deviation \u00b1 1.2% were found to vary significantly among the cortex vessels studied. The hypoxic response time to rise from 10 % to 90 % of maximum was 63 \u00b1 6 sec. The reverse response time for this event was 16 \u00b1 2 sec.", "doi": "10.1117/12.810036", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770C" }, { "id": "authors:bne1y-0d372", "collection": "authors", "collection_id": "bne1y-0d372", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906547", "type": "book_section", "title": "Monitoring the healing process of laser-induced microvascular lesions using optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical resolution photoacoustic microscopy (OR-PAM) possesses optical resolution and reveals endogenous optical absorption contrast, promising to be a valuable tool for in vivo microvascular imaging. In laser dermatology, OR-PAM can provide fruitful structural and functional information about the targeted microvascular lesions, such as their threedimensional (3D) morphology, precise location inside the tissue, and blood oxygenation within single vessels, which will facilitate accurate diagnosis and proper treatment. More importantly, the advantages of noninvasiveness and measurement consistency also permit OR-PAM to monitor the healing process of the laser-surgical wound noninvasively. In this work, we employed OR-PAM to monitor the healing process of microvascular lesions induced by nanosecond-pulsed laser. Our results indicate that OR-PAM could be a very useful tool in laser dermatology and laser microsurgery.", "doi": "10.1117/12.809327", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772I" }, { "id": "authors:43zfw-z1996", "collection": "authors", "collection_id": "43zfw-z1996", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906643", "type": "book_section", "title": "Improvements in time resolution of tomographic photoacoustic imaging using a priori information for multiplexed systems", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present results of investigations of the application of a priori information and sparse or limited-view algorithms to simultaneously improve imaging quality and timeresolution in photoacoustic tomography. Modified versions of existing MRI/CT algorithms such as constrained backprojection and keyhole imaging are evaluated as well as a new Wiener estimation methods for extrapolation of missing data from reference data sets. Simulations indicate the effectiveness of the approaches for accurate tracking of dynamic photoacoustic events for data sets with limited views (< 90 degrees) or tomographic views with up to 1/64 of the full data set. We present experimental data of contrast uptake and washout using a 512-element curved transducer with 1:8 electronic multiplexing that demonstrates high-resolution tomographic imaging with a temporal resolution of better than 150 milliseconds using these methods.", "doi": "10.1117/12.813558", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71771C" }, { "id": "authors:jyzfr-x9k08", "collection": "authors", "collection_id": "jyzfr-x9k08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905513", "type": "book_section", "title": "Monte Carlo simulation of light transport in dark-field confocal photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Xie", "given_name": "Zhixing", "clpid": "Xie-Zhixing" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A modified MC convolution method for integration extension of MC simulation is developed for finite photon beam with random shape of translational or rotational invariance, which is proven consistent with the conventional convolution extension of MC simulation for normal incident finite beam. The method is applied to analyze the positions of fluence foci and ratios of fluence at the focus and surface which are two key factors in the application of dark-field confocal and some interesting points are presented including: 1) The fluence profile has a saddle-like shape with highest peak in the bright field and low valley near the surface and a second rise in the center of dark field which is defined as the effective optical focus; 2) Besides a little peak near zero inner radius, the ratio of fluences at the focus and surface increases linearly with the inner radius, suggesting the large inner radius more advantageous to image at the effective optical focus; 3) The position of effective optical foci deepens linearly with the increase of the inner radius, suggesting that to get a high quality image of deeper target, a dark-field with larger size is more beneficial. But the position of fluence foci are far away from the foci of geometrical laser beam in high scattering tissue, so aligning the foci of geometrical laser beam and acoustic transducer doesn't guarantee that effective optical focus is accurately overlapping with the acoustic focus. An MC simulation with integration extension presented in this paper maybe helpful to determine where the acoustic focus should be to maximize the SNR in tissue imaging; 4) incident angle makes little difference to ratio of fluences at the focus and surface and an incident angle between 30 and 50 degrees gives the highest fluence at the effective optical focus; 5) the depth of fluence focus is insensitive to the incident angle.", "doi": "10.1117/12.810254", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 717717" }, { "id": "authors:tx6m4-44h95", "collection": "authors", "collection_id": "tx6m4-44h95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906116", "type": "book_section", "title": "In vivo noninvasive monitoring of microhemodynamics using optical-resolution photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Microvascular autoregulation is an intrinsic ability of vascular beds to compensate for the fluctuation in blood flow and tissue oxygen delivery. This function is crucial to maintaining the local metabolic activity. Here, using optical-resolution photoacoustic microscopy (OR-PAM), we clearly observed vasomotion and vasodilation in the intact mouse microcirculation in vivo in response to the changes in physiological state. Our results show that a significant lowfrequency vasomotion can be seen under hyperoxia but not hypoxia. Moreover, significant vasodilation is observed when the animal status is switched from hyperoxia to hypoxia. Our data show that arterioles have more pronounced vasodilation than venules.", "doi": "10.1117/12.809297", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770H" }, { "id": "authors:c6hav-qbr15", "collection": "authors", "collection_id": "c6hav-qbr15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906303", "type": "book_section", "title": "High-NA-based virtual point detectors for photoacoustic imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We demonstrated the focal point of a high-numerical-aperture (NA) ultrasonic transducer can be used as a virtual point detector. This virtual point detector detects omnidirectionally over a wide acceptance angle. It also combines a large active transducer surface and a small effective virtual detector size, thus the sensitivity is high compared with that of a real point detector, and the aperture effect is small compared with that of a finite size transducer. Phantom experiments are provided to demonstrate the applications of high-NA-based virtual point detectors in photoacoustic tomography and thermoacoustic tomography. The virtual point detector is also used to image the cerebral cortex of mice.", "doi": "10.1117/12.808514", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770R" }, { "id": "authors:yk42v-3kd50", "collection": "authors", "collection_id": "yk42v-3kd50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906201", "type": "book_section", "title": "Noninvasive photoacoustic sentinel lymph node mapping using Au nanocages as a lymph node tracer in a rat model", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Cobley", "given_name": "Claire M.", "clpid": "Cobley-C-M" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Sentinel lymph node biopsy (SLNB) has been widely performed and become the standard procedure for axillary staging in breast cancer patients. In current SLNB, identification of SLNs is prerequisite, and blue dye and/or radioactive colloids are clinically used for mapping. However, these methods are still intraoperative, and especially radioactive colloids based method is ionizing. As a result, SLNB is generally associated with ill side effects. In this study, we have proposed near-infrared Au nanocages as a new tracer for noninvasive and nonionizing photoacoustic (PA) SLN mapping in a rat model as a step toward clinical applications. Au nanocages have great features: biocompatibility, easy surface modification for biomarker, a tunable surface plasmon resonance (SPR) which allows for peak absorption to be optimized for the laser being used, and capsule-type drug delivery. Au nanocage-enhanced photoacoustic imaging has the potential to be adjunctive to current invasive SLNB for preoperative axillary staging in breast cancer patients.", "doi": "10.1117/12.809676", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772L" }, { "id": "authors:67qhk-csd55", "collection": "authors", "collection_id": "67qhk-csd55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906383", "type": "book_section", "title": "M-mode photoacoustic flow imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Fang", "given_name": "Hui", "clpid": "Fang-Hui" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Recently, there has been a growing interest in the development of photoacoustic flow measuring methods aimed to study microvascular blood flow in deep tissue. Here, we describe a method of M-mode photoacoustic flow imaging, where a photoacoustic microscope equipped with a high repetition rate pulsed dye laser is used. As a demonstration, we studied the flow of a diluted suspension of carbon glassy particles in a small tube, and extracted the flow profile. Potentially, the method can be applied to detect the blood flow in microvessels either directly or by injecting optically absorbing particles.", "doi": "10.1117/12.810159", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772M" }, { "id": "authors:wnrp9-xw230", "collection": "authors", "collection_id": "wnrp9-xw230", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906917", "type": "book_section", "title": "Novel breast cancer detection system combining both thermoacoustic (TA) and photoacoustic (PA) tomography using carbon nanotubes (CNTs) as a dual contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Pramanik", "given_name": "Manojit", "clpid": "Pramanik-M" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Swierczewska", "given_name": "Magdalena", "clpid": "Swierczewska-M" }, { "family_name": "Green", "given_name": "Danielle", "clpid": "Green-D" }, { "family_name": "Sitharaman", "given_name": "Balaji", "clpid": "Sitharaman-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report here a novel breast cancer scanner using microwave and light excitation and ultrasound detection. This combined thermoacoustic and photoacoustic tomography scanner is a nonionizing low cost system that can potentially provide high-resolution, dual contrast (microwave and light absorption) three dimensional images of the breast. Front breast compression will be used in this scanner to alleviate patient discomfort, experienced in side breast compression during traditional X-ray mammography. This scanner will use dry instead of gel ultrasonic coupling. We have also developed a carbon nanotube-based contrast agent for both thermoacoustic and photoacoustic imaging. In the future, targeted molecular photoacoustic and thermoacoustic imaging should be possible using this contrast agent.", "doi": "10.1117/12.809230", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71772G" }, { "id": "authors:p5dsw-xyw15", "collection": "authors", "collection_id": "p5dsw-xyw15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905238", "type": "book_section", "title": "In-vivo imaging of microcirculation using integrated photoacoustic and optical-coherence microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Maslov", "given_name": "Konstantin I.", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic imaging and optical coherence tomography have complementary imaging contrasts. Photoacoustic imaging is sensitive to optical absorption, thus is able to generate detailed maps of deep microvasculature in vivo. Optical coherence tomography exploits the optical scattering contrast, and can provide real-time, micrometer-resolution imaging of tissue. We integrate an optical-resolution photoacoustic microscopy and a spectral-domain optical coherence tomography into a single system. Our preliminary experiments showed that it could be a valuable imaging tool for microcirculation studies in vivo.", "doi": "10.1117/12.809323", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770I" }, { "id": "authors:abhbb-kf169", "collection": "authors", "collection_id": "abhbb-kf169", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100906012", "type": "book_section", "title": "A fast 512-element ring array photoacoustic imaging system for small animals", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Huang", "given_name": "Fei", "clpid": "Huang-Fei" }, { "family_name": "Guo", "given_name": "Puyun", "clpid": "Guo-Puyun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A 512-element photoacoustic tomography system for small animal imaging using a ring ultrasound array has been developed. The system features a 5 MHz piezocomposite transducer array formed into a complete circular aperture. Custom receiver electronics consisting of dedicated preamplifiers, 8:1 multiplexed post-amplifiers, and a 64-channel data acquisition module provide full tomographic imaging at up to 8 frames/second. We present details of the system design along with characterization results of the resolution, imaging volume, and sensitivity. Small animal imaging performance is demonstrated through images of mice brain vasculature at different depths and real-time spectroscopic scans. This system enables real-time tomographic imaging for functional photoacoustic studies for the first time.", "doi": "10.1117/12.812406", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-24", "pages": "Art. No. 71770B" }, { "id": "authors:4nbec-3t481", "collection": "authors", "collection_id": "4nbec-3t481", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905142", "type": "book_section", "title": "Three-dimensional photoacoustic tomography of small animal brain with a curved array transducer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2009", "author": [ { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present the application of an optimized curved array photoacoustic tomographic imaging system, which can provide rapid, high-resolution photoacoustic imaging of small animal brains. The system can produce a B-mode, 90-degree field-of-view image at sub-200 \u03bcm resolution at a frame rate of ~1 frame/second when a 10-Hz pulse repetition rate laser is employed. By rotating samples, a complete 360-degree scan can be achieved within 15 seconds. In previous work, two-dimensional ex vivo mouse brain cortex imaging has been reported. In the current work, we report three-dimensional small animal brain imaging obtained with the curved array system. The results are presented as a series of two-dimensional cross-sectional images. Besides structural imaging, the blood oxygen saturation of the animal brain cortex is also measured in vivo. In addition, the system can measure the time-resolved relative changes in blood oxygen saturation level in the small animal brain cortex. Finally, ultrasonic gel coupling, instead of the previously adopted water coupling, is conveniently used in near-real-time 2D imaging.", "doi": "10.1117/12.809590", "isbn": "9780819474230", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2009-02-12", "pages": "Art. No. 71770K" }, { "id": "authors:3c12c-eye63", "collection": "authors", "collection_id": "3c12c-eye63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100905041", "type": "book_section", "title": "Imaging of optical scattering contrast using ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Kothapalli", "given_name": "Sri-Rajasekhar", "clpid": "Kothapalli-S-R" }, { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Using a CCD-based speckle contrast detection scheme of ultrasound-modulated optical tomography (UOT), we show the feasibility of imaging objects having different optical scattering coefficients relative to the surrounding scattering medium. Our results show that the spatial resolution depends on the ultrasound parameters and the image contrast depends on the difference in scattering coefficient between the object and the surrounding medium. Experimental measurements are in agreement with Monte Carlo simulations and analytical calculations. This study complements previous UOT experiments that demonstrated optical absorption contrast. It also demonstrates that UOT complements photoacoustic tomography, which is sensitive to optical absorption contrast.", "doi": "10.1117/12.761391", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-03-11", "pages": "Art. No. 68561P" }, { "id": "authors:fsjya-tve13", "collection": "authors", "collection_id": "fsjya-tve13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904941", "type": "book_section", "title": "Realtime photoacoustic microscopy of murine cardiovascular and respiratory dynamics in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zemp", "given_name": "Roger J.", "clpid": "Zemp-R-J" }, { "family_name": "Song", "given_name": "Liang", "clpid": "Song-Liang" }, { "family_name": "Bitton", "given_name": "Rachel", "clpid": "Bitton-R" }, { "family_name": "Shung", "given_name": "K. Kirk", "clpid": "Shung-K-Kirk" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "While photoacoustic imaging has emerged as a promising modality in recent years, a key drawback of practical and widespread use of the technique has been slow imaging rates. We present a 30-MHz array-based photoacoustic imaging system that can acquire and display photoacoustic images in realtime. Realtime display is very helpful and provides the system operator the ability to better navigate and position the probe for selecting a desired anatomical field of view. The system is capable of imaging at 50 frames per second to depths of a few mm in tissue. We used this system to successfully image the beating hearts of young athymic nude mice in vivo. Also of interest was the ability to visualize microvascular changes during respiration.", "doi": "10.1117/12.763127", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-29", "pages": "Art. No. 68560G" }, { "id": "authors:675sp-6c284", "collection": "authors", "collection_id": "675sp-6c284", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904090", "type": "book_section", "title": "Photoacoustic Doppler flowmetry", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Fang", "given_name": "Hui", "clpid": "Fang-Hui" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report flow measurements based on the photoacoustic Doppler effect. We have performed flow experiments with a suspension of micrometer carbon particles and have detected the photoacoustic Doppler shift at various average flow speeds. We have also observed the directional dependence of the photoacoustic Doppler shift. Our experiment is based on the continuous wave (cw) photoacoustic generation. It is the goal of noninvasively monitoring hemodynamics in functional photoacoustic imaging that motivates our study.", "doi": "10.1117/12.761947", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561M" }, { "id": "authors:6v9q8-bc581", "collection": "authors", "collection_id": "6v9q8-bc581", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904638", "type": "book_section", "title": "RF diffraction effect in RF-induced thermoacoustic tomography: calibration and distortion", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Manojit", "given_name": "Pramanik", "clpid": "Manojit-P" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Because the wavelengths of radio-frequency (RF) waves used in thermoacoustic tomography (TAT) are comparable with the size of detected objects, RF diffraction plays important roles in TAT. The RF diffraction affects not only the global distribution of the RF field in the tissue, but also local RF energy deposition. In this paper, we discussed these two major effects. Both numerical simulations and phantom experiments are done to demonstrate these phenomena. We also provide a partial correction method for the image distortion and a calibration algorithm for image calibration.", "doi": "10.1117/12.763450", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 685612" }, { "id": "authors:g1j6y-ss644", "collection": "authors", "collection_id": "g1j6y-ss644", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904170", "type": "book_section", "title": "Improving the image quality of photoacoustic tomography (PAT) by using a negative acoustic lens", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Changhui", "clpid": "Li-Changhui" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Although a small point ultrasound transducer has a wide acceptance angle, its signal-to-noise (SNR) is low due to the high thermal-noise-induced electric voltages in the transducer, which is a result of its small active area. By contrast, a finite size flat transducer has high sensitivity (good SNR), but the acceptance angle is generally small, which limits its application in reconstruction-based photoacoustic tomography (PAT). In this paper, we report a negative lens concept to increase the acceptance angle for a flat transducer. We also provide phantom experiments that demonstrate this concept can greatly increase the detection region for PAT and without losing sensitivity.", "doi": "10.1117/12.763533", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 685623" }, { "id": "authors:fzkq1-46419", "collection": "authors", "collection_id": "fzkq1-46419", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903776", "type": "book_section", "title": "Monkey brain cortex imaging by use of photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography (PAT) is adopted to image the brain cortex of monkeys through the intact scalp and skull ex vivo. The reconstructed PAT image shows the main structure of the blood vessels on the monkey brain cortex. For comparison, the brain cortex is imaged without the scalp then imaged again without the scalp and skull. Ultrasound attenuation through the skull is also measured at various angles of incidence to illuminate the effect of the incident angle. This study demonstrates that PAT of the brain cortex is capable of surviving the ultrasound signal attenuation and distortion caused by a considerably thick skull.", "doi": "10.1117/12.762396", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 685608" }, { "id": "authors:pm8fp-j4m39", "collection": "authors", "collection_id": "pm8fp-j4m39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904849", "type": "book_section", "title": "Effects of wavelength-dependent fluence attenuation on the noninvasive photoacoustic imaging of hemoglobin oxygen saturation in subcutaneous vasculature in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Due to wavelength-dependent optical attenuation in the skin, the local fluence at a subcutaneous vessel varies with the optical wavelength in a spectral measurement. Hence compensation for such a spectral attenuation is necessary in quantitative measurements of the oxygen saturation of hemoglobin (sO_2) in blood vessels in vivo using photoacoustic (PA)imaging. Here, by employing a simplified double-layer skin model, we find that although the absolute value of sO_2 in a vessel is seriously affected by the volume fraction of blood and the spatially averaged sO_2 in the dermis, the difference of sO_2 between neighboring vessels is minimally affected. Based on in vivo experiments, we demonstrate that the difference in sO_2 between a typical artery and a typical vein is conserved before and after an experimentally acquired spectral compensation. This conservation holds regardless of the animal's systemic physiological state.", "doi": "10.1117/12.761984", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561T" }, { "id": "authors:gmzeg-cdt54", "collection": "authors", "collection_id": "gmzeg-cdt54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903668", "type": "book_section", "title": "Ultrasound-modulated optical tomography using four-wave mixing in photorefractive polymers", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Huiliang", "clpid": "Zhang-Huiliang" }, { "family_name": "Hemmer", "given_name": "Philip", "clpid": "Hemmer-P-R" }, { "family_name": "Wang", "given_name": "Peng", "clpid": "Wang-Peng" }, { "family_name": "Rokutanda", "given_name": "Shuji", "clpid": "Rokutanda-Shuji" }, { "family_name": "Yamamoto", "given_name": "Michiharu", "clpid": "Yamamoto-Michiharu" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound-modulated optical tomography uses a well focused ultrasound beam to modulate diffuse light inside soft biological tissues. This modality combines the advantages of ultrasound resolution with optical contrast. However, because of the low ultrasound modulation efficiency, the large background of un-modulated photons gives a low signal-to-noise ratio. Here we report a technique for detection of ultrasound-modulated light using a phase conjugated signal generated by four-wave mixing in a photorefractive polymer. The experimental results demonstrate the potential of this method to detect ultrasound-modulated optical signals in a highly scattering media with an excellent signal-to-noise ratio.", "doi": "10.1117/12.764987", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561S" }, { "id": "authors:qbs6h-spn32", "collection": "authors", "collection_id": "qbs6h-spn32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904263", "type": "book_section", "title": "Multi-bandwidth image reconstruction in photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Chou", "given_name": "Cheng-Ying", "clpid": "Chou-Cheng-Ying" }, { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Zhang", "given_name": "Jin", "clpid": "Zhang-Jin" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography (PAT), also referred to optoacoustic tomography, is a hybrid imaging technique that combines an optical contrast mechanism and ultrasonic detection principles. The laser-induced photoacoustic signals in PAT are broadband in nature, but only a bandpass approximation of the signal is recorded by use of a conventional ultrasonic transducers due to its limited bandwidth. To circumvent this, a PAT system has been developed that records photoacoustic signals by use of multiple ultrasonic transducers that possess different central frequencies. In this work, we investigate a sensor fusion methodology for combining the multiple measurements to obtain an estimate of the true photoacoustic signal that is superior to that obtainable by use of any single transducer measurement. From the estimated photoacoustic signals, three-dimensional images of the optical absorption distribution are reconstructed and are found to possess improved accuracy and statistical properties as compared to the single transducer case. Preliminary computer-simulation studies are presented to demonstrate and investigate the proposed method.", "doi": "10.1117/12.764127", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561G" }, { "id": "authors:hjmbj-53904", "collection": "authors", "collection_id": "hjmbj-53904", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904746", "type": "book_section", "title": "Photoacoustic generation of focused ultrasonic pulses with predefined temporal profiles including quasi-unipolar pressure pulses", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "One of the applications of the photoacoustic effect in biomedical research is generation of ultra-short acoustic pressure pulses in tissue. An acoustic wave is generated directly in tissue or in an acoustically well coupled immersion liquid, thus avoiding mechanical resonances of the piezoelectric ultrasonic transducer. Although laser generation of the unipolar pressure pulses has been proposed and used before, little attention was paid to the change of the temporal shape of the pulse when it propagates from a transducer. Here we derive simple mathematical solution which helps to predict the pulse shape in the focal region of the transducer and to experimentally verify theoretical calculations showing generation of short quasi-unipolar pressure pulses.", "doi": "10.1117/12.763972", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68560C" }, { "id": "authors:kdj1c-3r102", "collection": "authors", "collection_id": "kdj1c-3r102", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903866", "type": "book_section", "title": "Pulsed ultrasound-modulated optical tomography using spectral hole-burning", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Youzhi", "clpid": "Li-Youzhi" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Zhang", "given_name": "Huiliang", "clpid": "Zhang-Huiliang" }, { "family_name": "Wagner", "given_name": "Kelvin H.", "clpid": "Wagner-K-H" }, { "family_name": "Hemmer", "given_name": "Philip", "clpid": "Hemmer-P-R" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a novel optical quantum sensor using spectral hole-burning for detecting signals in ultrasound-modulated optical tomography. In this technique, we utilize the capability of sub-MHz spectral filtering afforded by a spectral hole burning crystal to select the desired spectral component from the ultrasound-modulated diffuse light. This technique is capable of providing a large etendue, processing a large number of speckles in parallel, tolerating speckle decorrelation, and imaging in real-time. Experimental results are presented.", "doi": "10.1117/12.774157", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561R" }, { "id": "authors:ndr0z-a5v14", "collection": "authors", "collection_id": "ndr0z-a5v14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904468", "type": "book_section", "title": "Deep reflection-mode photoacoustic imaging of internal organs", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A deep reflection-mode photoacoustic imaging system was developed and demonstrated to possess a maximum imaging depth up to 38 mm in chicken breast tissue. Using this system, structures in the thoracic cavity and vasculature in cervical area of rats were clearly imaged. Particularly, part of the heart was imaged. In the thoracic cavity, the right atrium imaged, which is one of deepest, was situated ~7 mm deep. In the cervical area, common carotid artery and jugular vein were imaged, which are appropriate for the study of oxygenation between artery and vein. In the abdominal cavity, the embedded structures of a kidney, spinal cord, and vena cava inferior were also clearly imaged in situ and in vivo. The depth of the vena cava inferior was as deep as ~15 mm in vivo. This study shows the depth capability of the system in animals. This imaging modality can be a useful tool to diagnose the disease of organs by assessing the morphological and functional changes in the blood vessels and the organs.", "doi": "10.1117/12.761389", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561W" }, { "id": "authors:3x84p-3xn07", "collection": "authors", "collection_id": "3x84p-3xn07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904364", "type": "book_section", "title": "Optical-resolution confocal photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Hu", "given_name": "Song", "clpid": "Hu-Song" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A confocal photoacoustic microscope with improved lateral resolution has been developed by employing stronglyfocused bright field optical illumination and spherically focused 75-MHz ultrasonic detection. The lateral resolution was experimentally measured to be 5 \u03bcm and the axial resolution was estimated to be 15 \u03bcm. The maximum imaging depth was demonstrated to be greater than 0.7 mm. In in vivo experiments, microvessels with a diameter of ~ 5 \u03bcm are imaged in small animals.", "doi": "10.1117/12.763889", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561I" }, { "id": "authors:16ndh-9qt95", "collection": "authors", "collection_id": "16ndh-9qt95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903470", "type": "book_section", "title": "Noninvasive mapping of the electrically stimulated mouse brain using photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Stein", "given_name": "Erich W.", "clpid": "Stein-E-W" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic imaging techniques possess high optical contrast with ultrasonic resolution while exceeding imaging depths of pure optical techniques, affording high resolution images deep within scattering biological tissues. In this work, we employ reflection-mode photoacoustic microscopy to non-invasively monitor hemodynamic contrasts and map brain activity. Changes in vascular dynamics of the mouse somatosensory cortex were evoked through electrical stimulation of the hindpaw, resulting in increased photoacoustic intensities spatially correlated with contra-lateral vasculature. Results demonstrate the ability to map brain activation with vascular resolution in three-dimensions, as well as monitor single-vessel hemodynamics with millisecond temporal resolution. Furthermore, these results implicate the feasibility of photoacoustic microscopy to probe intra-cortical single-vessel hemodynamics and pave the way for more extensive functional brain imaging studies.", "doi": "10.1117/12.769508", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561J" }, { "id": "authors:ezq4x-6j206", "collection": "authors", "collection_id": "ezq4x-6j206", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903985", "type": "book_section", "title": "Photoacoustic tomography with novel optical contrast agents based on gold nanocages or nanoparticles containing near-infrared dyes", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Skrabalak", "given_name": "Sara", "clpid": "Skrabalak-S-E" }, { "family_name": "Stein", "given_name": "Erich", "clpid": "Stein-E-W" }, { "family_name": "Wu", "given_name": "Bin", "clpid": "Wu-Bin" }, { "family_name": "Wei", "given_name": "Xunbin", "clpid": "Wei-Xunbin" }, { "family_name": "Xia", "given_name": "Younan", "clpid": "Xia-Younan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Poly(ethylene glycol)-coated Au nanocages have been evaluated as a potential near-infrared (NIR) contrast agent for photoacoustic tomography (PAT). Previously, Au nanoshells were found to be an effective NIR contrast agent for PAT; however, Au nanocages, with their more compact sizes (<50 nm compared to >100 nm for Au nanoshells) and larger optical absorption cross-sections, should be better suited for in vivo applications. In this study, we tested Au nanocages as a contrast agent for PAT. The result suggests that Au nanocages are promising contrast agents for our applications. We also present PAT results when novel, dye-containing nanoparticles are used as contrast agents.", "doi": "10.1117/12.762401", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68560I" }, { "id": "authors:1ayaa-waq33", "collection": "authors", "collection_id": "1ayaa-waq33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903575", "type": "book_section", "title": "Toward functional ultrasound-modulated optical tomography: a phantom study", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present the feasibility of functional ultrasound-modulated optical tomography (UOT) in tissue phantoms with two optical wavelengths. By using intense acoustic bursts and a CCD camera-based speckle contrast detection technique, we observe variations of UOT signal at different optical absorptions. In addition, the results from Monte Carlo simulations highly correlate with the experimental outcomes. By irradiating the sample at two optical wavelengths, we quantitatively estimate the total concentration and the concentration ratio of double dyes in inclusions inside tissue phantoms. Therefore, UOT is potentially able to supply functional imaging of the total concentration and oxygen saturation of hemoglobin non-invasively in biological tissues.", "doi": "10.1117/12.761377", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68561U" }, { "id": "authors:f5tdz-7b571", "collection": "authors", "collection_id": "f5tdz-7b571", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100904552", "type": "book_section", "title": "Small animal imaging using a curved array photoacoustic tomography system", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Huang", "given_name": "Fei", "clpid": "Huang-Fei" }, { "family_name": "Castillo", "given_name": "Diego", "clpid": "Castillo-D" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report experimental imaging results with mice using an array-based photoacoustic tomography system designed for small animal imaging. The system features a 128-element curved transducer array with stage rotation to enable complete two-dimensional tomographic imaging in less than 15 seconds. High fidelity imaging of ex vivo mouse brain vasculature was achieved with resolution of vessels less than 200 microns in diameter in the cortex as well as the cerebellum. Images obtained using varying measurement surface angular spans clearly illustrate the impact on feature definition with orientation. The high sensitivity of the system was demonstrated by images of the brain vasculature with an overlying turbid medium (\u03bc_a = 0.03 cm^(-1) and \u03bc_s' ~ 7 cm^(-1) at 780 nm) of over 2 cm depth. In phantom experiments, high-quality images of blood tubing in a turbid medium were achieved at depths greater than 3 cm for incident fluences of less than 15 mJ/cm^2. These results illustrate the suitability for near real-time small animal imaging of deep tissue with high definition.", "doi": "10.1117/12.769238", "isbn": "9780819470317", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-28", "pages": "Art. No. 68560Q" }, { "id": "authors:w1g12-ht903", "collection": "authors", "collection_id": "w1g12-ht903", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903380", "type": "book_section", "title": "Optical coherence computed tomography", "book_title": "Complex Dynamics and Fluctuations in Biomedical Photonics V", "author": [ { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Tuchin", "given_name": "Valery V.", "clpid": "Tuchin-V-V" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We proposed a novel time-resolved optical tomography, optical coherence computed tomography. It married the key concepts of time-resolved diffuse optical tomography and optical coherence tomography. Both ballistic and multiple-scattered photons were measured at multiple source-detection positions by low-coherence interferometry. It measures the reemitted light with a temporal resolution of 56 femtoseconds, which is much better than the resolution of conventional time-resolved detection systems. A light-tissue interaction model was established using the time-resolved Monte Carlo method. The optical properties were then reconstructed by solving the inverse time-resolved radiative transport problem under the first Born approximation. Our initial results showed the potential of this technology to bridge the gap between diffuse optical tomography and optical coherence tomography.", "doi": "10.1117/12.761431", "isbn": "9780819470300", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2008-02-06", "pages": "Art. No. 68550H" }, { "id": "authors:j5hw6-1s758", "collection": "authors", "collection_id": "j5hw6-1s758", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903284", "type": "book_section", "title": "In-vivo imaging of nanoshell extravasation from solid tumor vasculature by photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Schwartz", "given_name": "Jon A.", "clpid": "Schwartz-J-A" }, { "family_name": "Wang", "given_name": "James", "clpid": "Wang-James-Chunjay" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this study, high resolution reflection-mode (backward-mode) photoacoustic microscopy (PAM) is used to noninvasively image progressive extravasation and accumulation of nanoshells within a solid tumor in vivo. This study takes advantage of the strong near-infrared absorption of nanoshells, a novel type of optically tunable gold nanoparticles that tend to extravasate from leaky tumor vasculatures (i.e., passive targeting) via the \"enhanced permeability and retention\" effect due to their nanoscale size. Tumors were grown in immunocompetent BALB/c mice by subcutaneous inoculation of CT26.wt murine colon carcinoma cells. PEGylated nanoshells with a peak optical absorption at ~800 nm were intravenously administered. Pre-scans prior to nanoshell injection were taken using a 584-nm laser source to highlight blood content and an 800-nm laser source to mark the background limit for nanoshell accumulation. After injection, the three-dimensional nanoshell distribution inside the tumor was monitored by PAM for 7 hours. Experimental results show that nanoshell accumulation is heterogeneous in tumors: more concentrated within the tumor cortex and largely absent from the tumor core. This correlates with others' observation that drug delivery within tumor cores is ineffective because of both high interstitial pressure and tendency to necrosis of tumor cores. Since nanoshells have been recently applied to thermal therapy for subcutaneous tumors, we anticipate that PAM will be important to this therapeutic technique.", "doi": "10.1117/12.697722", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-28", "pages": "Art. No. 64370B" }, { "id": "authors:r0a84-7hq30", "collection": "authors", "collection_id": "r0a84-7hq30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100903185", "type": "book_section", "title": "Experimental investigation of target and transducer effects on quantitative image reconstruction in photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Huang", "given_name": "Fei", "clpid": "Huang-Fei" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Castillo", "given_name": "Diego", "clpid": "Castillo-D" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In principle, absorbed energy profiles can be exactly reconstructed from photoacoustic measurements on a closed surface. Clinical applications, however, involve compromises due to transducer focus, frequency characteristics, and incomplete measurement apertures. These tradeoffs introduce artifacts and errors in reconstructed absorption distributions that affect quantitative interpretations as well as qualitative contrast between features. The quantitative effects of target geometry, limited measurement surfaces, and bandpass transducer frequency response have been investigated using a ring transducer system designed for small animal imaging. The directionality of photoacoustic radiation is shown to increase with target aspect ratio, producing proportionate overestimates of absorption values for two-dimension apertures less than approximately 150 degrees. For all target geometries and orientations, mean absorption values approach the full view values for hemicircular measurement surfaces although the true spatial uniformity is recovered only with the complete surface. The bandpass transducer frequency spectrum produces a peaked amplitude response biased toward spatial features ranging from 1 to 8 times the system resolution. We discuss the implications of these results for design of clinical systems.", "doi": "10.1117/12.707245", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-27", "pages": "Art. No. 64371F" }, { "id": "authors:0kyh4-zw103", "collection": "authors", "collection_id": "0kyh4-zw103", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902998", "type": "book_section", "title": "Laser speckle statistics in ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zemp", "given_name": "Roger", "clpid": "Zemp-R-J" }, { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Kim", "given_name": "Chulhong", "clpid": "Kim-Chulhong" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound-Modulated Optical Tomography is a novel biophotonic imaging technique that provides optical contrast with ultrasonic spatial resolution. High temporal coherence laser light and focused ultrasound are transmitted into tissue. Light passing through the acoustic focal volume experiences modulation due to acoustically induced changes in optical index of refraction and optical scatterer displacement. A component of the modulated light may be detected using various detection schemes. One such scheme detects changes in the contrast of optical speckles using a CCD camera. We use statistical optics to derive expressions for the speckle statistics as a function of acoustic parameters. We demonstrate theoretically and experimentally that low acoustic frequencies induce much larger modulation compared with high frequency ultrasound. Theoretically computed values for the speckle contrast are compared with experimental values.", "doi": "10.1117/12.700547", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-27", "pages": "Art. No. 64371L" }, { "id": "authors:bz1ta-gt045", "collection": "authors", "collection_id": "bz1ta-gt045", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902760", "type": "book_section", "title": "A curved array photoacoustic tomography system for small animal imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Aguirre", "given_name": "Andres", "clpid": "Aguirre-A" }, { "family_name": "Gamelin", "given_name": "John", "clpid": "Gamelin-J" }, { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Huang", "given_name": "Fei", "clpid": "Huang-Fei" }, { "family_name": "Castillo", "given_name": "Diego", "clpid": "Castillo-D" }, { "family_name": "Guo", "given_name": "Puyun", "clpid": "Guo-Puyun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have developed and tested a photoacoustic imaging system based on a 128 element curved-phased ultrasonic array, which spans a quarter of a complete circle with a radius of curvature equal to 25mm. The center frequency of the array is 5 MHz with 60% bandwidth. The physical dimensions of the elements are 10x0.3mm (elevation x azimuth) with an elevation focus of 19mm. Earlier we reported acoustic measurements of the axial and lateral resolutions of the system that were limited by the impulse response of the narrowband source used in the test. In this paper we discuss photoacoustic characterization of the system including resolution and sensitivity. The array forms the building block for a 512-element ring designed for complete tomographic imaging of small animals. Imaging results of phantoms will be compared with simulations.", "doi": "10.1117/12.707548", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370V" }, { "id": "authors:kvqsa-rwq74", "collection": "authors", "collection_id": "kvqsa-rwq74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100901740", "type": "book_section", "title": "Boundary effects on image reconstruction in photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Exact photoacoustic tomography requires scanning over a 4\u03c0 solid angle in 3D. The ultrasound detection window, however, is often limited, which makes a full scan impossible. For example, when a boundary lies closely to an object, the scanning region can cover only less than 4\u03c0 in 3D. Because of incomplete information, the resolution, SNR, and fidelity of the resulting image deteriorate. Boundaries, however, can be used to our advantage; we proposed post-processing algorithms in image reconstruction to make partially scanned data complete. Here, we show the efficacy of the post-processing algorithms with both numerical and experimental results. Indeed, the algorithms can improve the resolution, SNR, and fidelity.", "doi": "10.1117/12.698360", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370W" }, { "id": "authors:4kwdb-3pw75", "collection": "authors", "collection_id": "4kwdb-3pw75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902366", "type": "book_section", "title": "Iron-oxide nanoparticles as a contrast agent in thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Jin", "given_name": "Xing", "clpid": "Jin-Xing" }, { "family_name": "Keho", "given_name": "Aaron", "clpid": "Keho-A" }, { "family_name": "Meissner", "given_name": "Kenith", "clpid": "Meissner-K-E" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We investigate the feasibility of using iron oxide nanoparticles as a contrast agent for radiofrequency (RF) induced thermoacoustic tomography. Aqueous colloids of iron oxide (Fe3O4) nanoparticles have been synthesized and characterized. The synthesis method yielded citrate-stabilized, spherical particles with a diameter of approximately 10 nm. The complex permittivity of the colloids was measured with a coaxial probe and vector network analyzer, and the microwave absorption properties were calculated by using a relationship between the complex permittivity and absorption coefficients. Using our pulsed thermoacoustic imaging system at 3 GHz, the time-resolved thermoacoustic responses of those colloids were measured and compared to that of deionized water. Finally, two-dimensional thermoacoustic images were acquired from iron oxide colloids in a tissue phantom. The iron oxide colloids produced an enhancement in RF absorption of up to three times that of deionized water at 3 GHz. The enhancement increased rapidly with decreasing frequency of the RF excitation source. A corresponding increase in time-resolved thermoacoustic signal of more than two times was demonstrated. Our results indicate that iron oxide nanoparticles have the potential to produce enhanced thermoacoustic signals and to provide molecular imaging with functionalized contrast agents for thermoacoustic tomography.", "doi": "10.1117/12.698329", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370E" }, { "id": "authors:ntz4z-t5163", "collection": "authors", "collection_id": "ntz4z-t5163", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902279", "type": "book_section", "title": "Continuous-wave photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We have built a photoacoustic microscope (PAM) using an amplitude-modulated continuous-wave (CW) laser source, which is an inexpensive 120-mW laser diode. By using a bowl-shaped piezoelectric transducer, whose numerical aperture is 0.85 and resonance frequency is 2.45 MHz, we have experimentally demonstrated a lateral resolution of 600 \u00b5m, an axial resolution of 700 \u00b5m, and a signal-to-noise ratio (SNR) as high as 43 dB. Although the SNR in the CW PAM system is an order of magnitude worse than that of the pulsed-laser-based PAM system, CW PAM shows potential for biomedical applications as it uses durable and inexpensive semiconductor lasers, which will significantly reduce operation costs of the PAM systems.", "doi": "10.1117/12.702240", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370P" }, { "id": "authors:2fmrz-x4m40", "collection": "authors", "collection_id": "2fmrz-x4m40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902561", "type": "book_section", "title": "A study of reconstruction in photoacoustic tomography with a focused transducer", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "So far most rigorous reconstruction algorithms for photoacoustic tomography (PAT), e.g., the modified back-projection algorithm, have been developed based on ideal point detectors. However, a flat unfocused transducer is commonly used in PAT, thus suffering from the finite aperture effect - tangential resolution deteriorates as the imaging point moves away from the scanning center. Based on a virtual-point-detector concept, we propose a PAT reconstruction with a focused transducer to improve the degraded tangential resolution. We treat the focal point of the focused transducer as a virtual-point detector, which means that delays applied in reconstruction are relative to the focal point. The geometric focus defines propagation path of photoacoustic signals. The simulation results show that compared with PAT with an unfocused transducer, PAT with a focused transducer having an f-number of 2.5 significantly improves tangential resolution by 29 microns up to 791 microns at the imaging positions of at least 4 mm away from the scanning center. The farther the imaging positions away from the scanning center, the larger the improvement. In the region of 4 mm away from the scanning center, PAT with a focused transducer slightly degrades the tangential resolution by up to 70 microns. The improvement in tangential resolution comes with a compromise of loss in radial resolution by 26 microns up to 79 microns depending on the distance from the scanning center. In terms of the significant improvement in tangential resolution, the loss in radial resolution is tolerable, especially for imaging of big objects, e.g., breast.", "doi": "10.1117/12.703716", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64371E" }, { "id": "authors:j2gm8-t7628", "collection": "authors", "collection_id": "j2gm8-t7628", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902645", "type": "book_section", "title": "Transcranial ultrasonic wave propagation simulation: skull insertion loss and recovery", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Liu", "given_name": "Lanbo", "clpid": "Liu-Lanbo" }, { "family_name": "He", "given_name": "Kuang", "clpid": "He-Kuang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Severe energy dissipation and waveform aberration in ultrasonic wave propagation due to the human skull remain major challenges to achieving good focus in high intensity focused ultrasound (HIFU) brain therapy and high-resolution thermoacoustic tomography (TAT) of the human brain. With the inclusion of the skull insertion loss, we numerically simulated the ultrasonic wave propagation using the pseudospectral time domain (PSTD) algorithm for TAT setup. We then applied the redatuming scheme through downward and upward continuation originated in seismic signal processing to eliminate the diffraction caused by the irregularity of the skull and to recover the insertion loss due mainly to the diploes layer of the skull. This approach, after further validation, is aimed to recover wave energy dissipation and waveform aberration in ultrasonic measurements applied to both trans-skull imaging (ultrasound propagates outward) and therapy (ultrasound propagates inward).", "doi": "10.1117/12.698237", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370X" }, { "id": "authors:hgfjs-4yn92", "collection": "authors", "collection_id": "hgfjs-4yn92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902012", "type": "book_section", "title": "Portable real-time photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "To make a photoacoustic microscope (PAM) suitable for clinical applications, we have developed a portable PAM system with high frame rate. The probe for this portable PAM system is a small hand-held unit, which is connected with the rest of the system with an optical fiber and electrical cables. The probe can be maneuvered easily and pressed against the region of interest at various anatomical sites. By employing a tunable laser with a repetition rate up to 1 kHz, this portable PAM system has reduced its acquisition time to less than one second for each cross-sectional image. We have applied this system to animals as well as humans to acquire cross-sectional images with a maximum imaging depth of 5 mm, a lateral resolution of better than 100 \u00b5m, and an axial resolution of 35 \u00b5m.", "doi": "10.1117/12.702227", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 643727" }, { "id": "authors:0zva6-d4277", "collection": "authors", "collection_id": "0zva6-d4277", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100901921", "type": "book_section", "title": "High-resolution burn imaging in pig skin by photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Existing noninvasive imaging modalities fail to provide high-resolution depth-resolved imaging of skin burns in large depths. Hence, the measurement of burn depth, especially for partial-thickness burn, remains inaccurate. We used photoacoustic microscopy to measure the depth of acute thermal burns by imaging the microvasculature damage. In this work, partial-thickness burns were induced in vivo on pig skin. Limited by the flexibility of the photoacoustic scanning system, photoacoustic images of the burns were acquired after skin excision. Experimental results show that burn depth increases with longer heating duration. The maximum imaged burn depth measures \u223c1.7 mm with a depth resolution of 15 \u00b5m.", "doi": "10.1117/12.698005", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64370A" }, { "id": "authors:0m30f-cmh75", "collection": "authors", "collection_id": "0m30f-cmh75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100902463", "type": "book_section", "title": "Adaptive and robust techniques (ART) for thermoacoustic and photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Xie", "given_name": "Yao", "clpid": "Xie-Yao" }, { "family_name": "Guo", "given_name": "Bin", "clpid": "Guo-Bin" }, { "family_name": "Li", "given_name": "Jian", "orcid": "0000-0003-0297-6528", "clpid": "Li-Jian" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this paper, we present new Adaptive and Robust Techniques (ART) for microwave-based thermoacoustic tomography (TAT) and laser-based photo-acoustic tomography (PAT), and study their performances for breast cancer detection. TAT and PAT are emerging medical imaging techniques that combine the merits of high contrast due to electromagnetic or laser stimulation and high resolution offered by thermal acoustic imaging. The current image reconstruction methods used for TAT and PAT, such as the widely used Delay-and-Sum (DAS) approach, are data-independent and suffer from low resolution, high sidelobe levels, and poor interference rejection capabilities. The data-adaptive ART can have much better resolution and much better interference rejection capabilities than their data-independent counterparts. By allowing certain uncertainties, ART can be used to mitigate the amplitude and phase distortion problems encountered in TAT and PAT. Specifically, in the first step of ART, RCB is used for waveform estimation by treating the amplitude distortion with an uncertainty parameter. In the second step of ART, a simple yet effective peak searching method is used for phase distortion correction. Compared with other energy or amplitude based response intensity estimation methods, peak searching can be used to improve image quality with little additional computational costs. Moreover, since the acoustic pulse is usually bipolar: a positive peak, corresponding to the compression pulse, and a negative peak, corresponding to the rarefaction pulse, we can further enhance the image contrast in TAT or PAT by using the peak-to-peak difference as the response intensity for a focal point. The excellent performance of ART is demonstrated using both simulated and experimentally measured data.", "doi": "10.1117/12.698391", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 643715" }, { "id": "authors:maa6c-6tw17", "collection": "authors", "collection_id": "maa6c-6tw17", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100901651", "type": "book_section", "title": "Deep reflection-mode photoacoustic imaging and resolution scalability with depth", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A deep reflection-mode photoacoustic (PA) imaging system was designed and implemented to visualize deep structures in biological tissues. To achieve good penetration depth, we chose near IR laser pulses at 804 nm wavelength for the generation of photoacoustic waves. To avoid overshadowing the deep PA signals by the surface PA signals, we employed dark-field illumination. To achieve good lateral resolution, we chose spherically focused high-numerical-aperture ultrasonic transducers with 5 MHz or 10 MHz center frequencies. By using these transducers, we achieved 153 \u03bcm and 130 \u03bcm axial resolutions, respectively, at 19.5 mm depth in 10% porcine gelatin containing 1% intralipid. The system was applied to imaging internal organs of small animals. Compared with our previous high-frequency (50-MHz) photoacoustic microscope, we scaled up the imaging depth while maintaining the ratio of the imaging depth to axial resolution more than 100. In addition, we studied the scalability of the imaging depth and the resolution with ultrasound frequency.", "doi": "10.1117/12.698823", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 643722" }, { "id": "authors:dqea5-smw33", "collection": "authors", "collection_id": "dqea5-smw33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100901505", "type": "book_section", "title": "Photoacoustic tomography with a virtual point detector", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Yang", "given_name": "Xinmai", "clpid": "Yang-Xinmai" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We devise and explore a ring-shaped acoustic detector associated with a virtual point detector concept for photoacoustic tomography. The center of the ring transducer scans a circle around the object to be imaged and then is treated as an omni-directional virtual point detector in photoacoustic image reconstruction. The virtual point detector introduces a space-invariant point spread function in photoacoustic image reconstruction and thus improves the tangential resolution, which is due to the finite aperture. Compared with a real point detector, the virtual point detector can provide similar spatial resolution but better SNR. Compared with a real finite-aperture detector, the virtual point detector can provide similar SNR but better spatial resolution. In addition, because of its virtual feature, the virtual point detector can be placed very close to and even inside of a tissue sample to locally scan a region of interest, which yields good SNR and spatial resolution.", "doi": "10.1117/12.698367", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 643718" }, { "id": "authors:9wn0j-xze26", "collection": "authors", "collection_id": "9wn0j-xze26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180921-100901819", "type": "book_section", "title": "Correlation transfer equation for multiply scattered light modulated by an ultrasonic pulse: an analytical model and Monte Carlo simulation", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present derivation of the temporal correlation transfer equation (CTE) for multiply scattered light modulated by an ultrasound pulse. The equation can be used to obtain the time-varying specific intensity of light produced by a pulsed and nonuniform ultrasound field in optically scattering media that have a heterogeneous distribution of optical parameters. We also develop a Monte Carlo algorithm that can simulate the spatial distribution of the time-dependent power spectrum density of light modulated by a focused ultrasound pulse in optically scattering media with heterogeneous distributions of optically scattering and absorbing objects. Derivation is based on the ladder diagram approximation of the Bethe-Salpeter equation that assumes moderate ultrasound pressures. We expect these results to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues.", "doi": "10.1117/12.702600", "isbn": "9780819465504", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2007-02-13", "pages": "Art. No. 64371K" }, { "id": "authors:ddk3f-tf763", "collection": "authors", "collection_id": "ddk3f-tf763", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-111448655", "type": "book_section", "title": "Development of the correlation transfer equation of ultrasound-modulated multiply scattered light: a diagrammatic approach", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this paper, we develop a temporal correlation transfer equation (CTE) for ultrasound-modulated multiply scattered light. The equation can be used to obtain the temporal frequency spectrum of the optical intensity produced by a nonuniform ultrasound field in optically scattering media. Derivation of the CTE is based on the ladder diagram approximation of the Bethe-Salpeter equation. We expect the CTE to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues.", "doi": "10.1117/12.646264", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-07", "pages": "Art. No. 60861X" }, { "id": "authors:8aser-b9g06", "collection": "authors", "collection_id": "8aser-b9g06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-132743309", "type": "book_section", "title": "Boundary conditions in photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography has captured a significant amount of attention recently. Although several commercially available optical imaging modalities, including confocal microscopy, two-photon microscopy, and optical coherence tomography have been highly successful, none of these technologies can penetrate beyond ~1 mm into scattering biological tissues because all of them are based on ballistic and quasi-ballistic photons. Consequently, until now, there has been a void in high-resolution optical imaging beyond this depth limit. Photoacoustic tomography has filled this void by combining high ultrasonic resolution and high optical contrast in a single modality. Up until now, however, free-space ultrasound propagation has always been assumed in photoacoustic tomography. In this paper, boundary conditions that should be considered in certain imaging configurations are presented and their associated inverse solutions for image reconstruction are provided.", "doi": "10.1117/12.647818", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608611" }, { "id": "authors:r6prq-tey54", "collection": "authors", "collection_id": "r6prq-tey54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-110836733", "type": "book_section", "title": "A photoacoustic imaging system employing a curved-phased ultrasonic array and parallel electronics", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maurudis", "given_name": "Anastasios", "clpid": "Maurudis-A" }, { "family_name": "Huang", "given_name": "Fei", "clpid": "Huang-Fei" }, { "family_name": "Guo", "given_name": "Puyun", "clpid": "Guo-Puyun" }, { "family_name": "Yan", "given_name": "Shikui", "clpid": "Yan-Shikui" }, { "family_name": "Castillo", "given_name": "Diego", "clpid": "Castillo-D" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zhu", "given_name": "Quing", "clpid": "Zhu-Quing" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Real-time photoacoustic imaging requires ultrasonic array receivers and parallel data acquisition systems for the simultaneous detection of weak photoacoustic signals. In this paper, we introduce a newly completed ultrasonic receiving array system and report preliminary results of our measured point spread function. The system employs a curved ultrasonic phased array consisting of 128-elements, which span a quarter of a complete circle. The center frequency of the array is 5 MHz and the bandwidth is greater than 60%. In order to maximize the signal-to-noise ratio for photoacoustic signal detection, we utilized special designs for the analog front-end electronics. First, the 128 transducer-element signals were routed out using a 50-Ohm impedance matching PCB board to sustain signal integrity. We also utilize 128 low-noise pre-amplifiers, connected directly to the ultrasonic transducer, to amplify the weak photoacoustic signals before they were multiplexed to a variable-gain multi-stage amplifier chain. All front-end circuits were placed close to the transducer array to minimize signal lose due to cables and therefore improve the signal-to-noise ratio. Sixteen analog-to-digital converters were used to sample signals at a rate of 40 mega-samples per second with a resolution of 10-bits per sample. This allows us to perform a complete electronic scan of all 128 elements using just eight laser pulses.", "doi": "10.1117/12.648500", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60861Q" }, { "id": "authors:wnx4z-cb241", "collection": "authors", "collection_id": "wnx4z-cb241", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181026-110314901", "type": "book_section", "title": "Correction of the effects of acoustic heterogeneity on thermoacoustic tomography using transmission ultrasound tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Jin", "given_name": "Xing", "clpid": "Jin-Xing" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The effects of acoustic heterogeneities on thermoacoustic tomography (TAT) are examined and corrected. One assumption made in the existing reconstruction algorithms for thermoacoustic tomography is that biological tissue is acoustically homogeneous. In medical imaging applications, this assumption can cause blurring and distortion in the reconstructed images. This degradation of image quality can be compensated for by using an approximate distribution of the acoustic speed in the tissue. A method based on transmission ultrasound tomography, which is compatible with our thermoacoustic imaging setup, is developed to correct those effects. Experiments verify the validity of this method. The technique can be used to improve the image quality of thermoacoustic tomography.", "doi": "10.1117/12.645104", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860W" }, { "id": "authors:xv0ak-g8p70", "collection": "authors", "collection_id": "xv0ak-g8p70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-142530985", "type": "book_section", "title": "High-SNR ultrasound-modulated optical tomography with intense acoustic bursts", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Kim", "given_name": "Chul hong", "clpid": "Kim-Chul-hong" }, { "family_name": "Zemp", "given_name": "Roger J.", "clpid": "Zemp-R-J" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a novel signal-enhancement method for ultrasound modulated optical tomography that can increase the amount of modulated light, compared to previous methods. By applying intense acoustic bursts, particle displacements of several microns are possible at a very local scale. A CCD camera captured the speckle pattern emerging from a laser-illuminated tissue phantom and differences in laser speckle contrast were measured between ultrasound on and off states. When CCD triggering was synchronized with burst initiation, ultrasound radiation force-induced displacements were detected with our technique, and resulting shear waves were shown to degrade image contrast and spatial resolution. Deleterious effects of shear waves were minimized by delaying CCD camera acquisition several ms until shear waves are adequately attenuated. Our system signal-to-noise ratio (SNR) is sufficiently high to perform UOT scanning without signal averaging. Because of substantially improved SNR compared to previous techniques, the use of intense acoustic burst is a new promising method for ultrasound modulated optical tomography.", "doi": "10.1117/12.648533", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608617" }, { "id": "authors:rm09t-hf711", "collection": "authors", "collection_id": "rm09t-hf711", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-113009773", "type": "book_section", "title": "Imaging of gene expression in vivo with photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Zemp", "given_name": "Roger J.", "clpid": "Zemp-R-J" }, { "family_name": "Lungu", "given_name": "Gina", "clpid": "Lungu-Gina" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In the post-genomic era, there is an increasing interest in visualizing the expression of functional genes in vivo. With the assistance of the reporter gene technique, various imaging modalities have been adopted for this purpose. In vivo gene expression imaging promises to provide biologists with a powerful tool for deepening our understanding of developmental biology, expanding our knowledge of the genetic basis of disease, and advancing the development of medicine. In this paper, we demonstrate the feasibility of imaging gene expression with photoacoustic imaging, which offers unique absorption contrast with ultrasonic resolution in vivo. We mark tumors in rats with the lacZ reporter gene. The lacZ gene encodes an enzyme \u03b2-galactosidase, which yields a dark blue product when acting on a colorimetric assay called X-gal. Photoacoustic tomography at 650nm clearly visualizes the presence of this blue product. The spectroscopic method can also potentially improve specificity. Considering how many staining methods are used in traditional biology, we believe that photoacoustic techniques will revolutionize the field of molecular imaging. The further development of reporter gene systems with high absorbing products in the NIR region is needed.", "doi": "10.1117/12.646322", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608608" }, { "id": "authors:xw4xr-93b18", "collection": "authors", "collection_id": "xw4xr-93b18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-133916938", "type": "book_section", "title": "Optical and mechanical properties in photorefractive crystal based ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Huiliang", "clpid": "Zhang-Huiliang" }, { "family_name": "Xu", "given_name": "Xiao", "clpid": "Xu-Xiao" }, { "family_name": "Qing", "given_name": "De-Kui", "clpid": "Qing-De-Kui" }, { "family_name": "Hemmer", "given_name": "Philip", "clpid": "Hemmer-P-R" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound-modulated optical tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the optical and mechanical properties of biological soft tissues.", "doi": "10.1117/12.646155", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608616" }, { "id": "authors:2hp3t-86q59", "collection": "authors", "collection_id": "2hp3t-86q59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181026-105510268", "type": "book_section", "title": "Technical considerations in quantitative blood oxygenation measurement using photoacoustic microscopy in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Sivaramakrishnan", "given_name": "Mathangi", "clpid": "Sivaramakrishnan-M" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Using peak amplitude spectral PA measurements in the range of 570 - 600 nm, we found it possible to quantify blood oxygenation levels. Visible light illumination minimizes the inversion error of the PA measurements. Owing to high blood absorption in this optical regime, there is also an improved signal-to-noise ratio and less influence from optical scattering. To arrive at correct, and vessel size independent, SO_2 measurements, the central frequency of the ultrasonic transducer must be high enough to satisfy the relation \u00b5_a \u039b < 1, that is above 25 MHz for a chosen optical wavelength region, although lower frequency transducers may produce correct results after correction of the optical absorption spectra. However, additional efforts are needed to achieve accurate SO_2 values for in vivo measurements.", "doi": "10.1117/12.646265", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860R" }, { "id": "authors:02kre-36440", "collection": "authors", "collection_id": "02kre-36440", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181012-151234592", "type": "book_section", "title": "In vivo functional photoacoustic tomography of traumatic brain injury in rats", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Oh", "given_name": "Jung-Taek", "clpid": "Oh-Jung-Taek" }, { "family_name": "Song", "given_name": "Kwang-Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this study, we demonstrate the potential of photoacoustic tomography for the study of traumatic brain injury (TBI) in rats in vivo. Based on spectroscopic photoacoustic tomography that can detect the absorption rates of oxy- and deoxy-hemoglobins, the blood oxygen saturation and total blood volume in TBI rat brains were visualized. Reproducible cerebral trauma was induced using a fluid percussion TBI device. The time courses of the hemodynamic response following the trauma initiation were imaged with multi-wavelength photoacoustic tomography with bandwidth-limited spatial resolution through the intact skin and skull. In the pilot set of experiments, trauma induced hematomas and blood oxygen saturation level changes were detected, a finding consistent with the known physiological responses to TBI. This new imaging method will be useful for future studies on TBI-related metabolic activities and the effects of therapeutic agents.", "doi": "10.1117/12.645378", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860P" }, { "id": "authors:bkn35-76025", "collection": "authors", "collection_id": "bkn35-76025", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-113848213", "type": "book_section", "title": "Towards very high resolution imaging in ultrasound-modulated optical tomography of biological tissues", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Kothapalli", "given_name": "Sri-Rajasekhar", "clpid": "Kothapalli-S-R" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We explored the possibility of applying very high ultrasound frequencies to achieve very high resolution in ultrasound-modulated optical tomography of soft biological tissues. The ultrasound-modulated coherent light that traversed the scattering biological tissue was detected by a long-cavity and a large etendue confocal Fabry- Perot interferometer. We used various focused ultrasound transducers of 15 MHz, 30 MHz, and 50 MHz to obtain two dimensional images of optically absorbing objects positioned at a few millimeters depth below the surface of both optically scattering phantoms and soft biological tissue samples. This technology is complementary to other imaging technologies, such as confocal microscopy and optical-coherence tomography, and has potential for broad biomedical applications.", "doi": "10.1117/12.645285", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608614" }, { "id": "authors:cqz54-hhb27", "collection": "authors", "collection_id": "cqz54-hhb27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181026-110806396", "type": "book_section", "title": "Speckle in photoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography is emerging as a promising imaging modality for various biomedical applications. Unlike traditional ultrasound imaging that is plagued by strong speckle artifacts, no obvious speckle has so far been observed in photoacoustic images. We systematically studied the reason for this lack of speckle in photoacoustic tomography based on speckle contrast. Theoretical explanations were validated by simulation. The results here can serve as a basis for developing specific applications, such as tissue characterization, using photoacoustic methods.", "doi": "10.1117/12.646357", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860Y" }, { "id": "authors:9dm8c-9rj87", "collection": "authors", "collection_id": "9dm8c-9rj87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-143143362", "type": "book_section", "title": "Photoacoustic and thermoacoustic tomography with both optical and electrical contrasts", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "The absorption of electromagnetic energy causes thermal expansion and induces acoustic waves in biological tissues. Various tissues present particular characteristics in their absorption spectra. To acquire both photoacoustic and thermoacoustic images with multiple contrasts that reflect the absorption of electromagnetic energy, biological tissues are stimulated using laser and microwave pulses, respectively. Muscles with a rich blood supply strongly absorb green optical radiation, which provides excellent optical contrast. High water content tissues, such as connective tissue and muscle tissue, display high contrast to fatty tissues when imaged using microwave radiation. Most cancerous tissues have higher water and ionic concentrations, two characteristics that are also associated with angiogenesis and hemoglobin oxygen saturation. Therefore, cancer diagnosis based on information from tissue properties over an electromagnetic spectrum from microwave to optical bands can be more accurate than was previously available.", "doi": "10.1117/12.646365", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608618" }, { "id": "authors:wc2cj-c6h68", "collection": "authors", "collection_id": "wc2cj-c6h68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181012-135925374", "type": "book_section", "title": "In vivo functional photoacoustic imaging of brain tumor vasculature", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Oh", "given_name": "Jung-Taek", "clpid": "Oh-Jung-Taek" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a study of the functional photoacoustic imaging of tumor hypoxia in mice in vivo. Based on spectroscopic photoacoustic tomography that detects the optical absorption of oxy- and deoxy-hemoglobins, the blood oxygen saturation and the vascularization of brain tumors were visualized. U87 glioblastoma tumor cells were inoculated intracranially at a 3-mm depth from the surface of the nude mouse head seven days before the experiment. Increased blood content and hypoxia inside the tumor vasculature were detected through the intact skin and skull. This technique will be useful for future studies on tumor metabolic activities in the brain and hypoxia-related therapeutic resistance.", "doi": "10.1117/12.645391", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860C" }, { "id": "authors:xdapj-25d46", "collection": "authors", "collection_id": "xdapj-25d46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181012-152913491", "type": "book_section", "title": "Three-dimensional in vivo near-infrared photoacoustic tomography of whole small animal head", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Song", "given_name": "Kwang Hyun", "clpid": "Song-Kwang-Hyun" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "A three-dimensional in vivo near-infrared photoacoustic tomography imaging system was newly designed and built to visualize the structure of a whole small animal head. For high sensitivity, a single flat 2.25MHz low frequency transducer, whose active element size is 6mm, was employed. To increase the penetration depth of light, a wavelength of 804nm in the NIR range, which matches the oxy- and deoxy-hemoglobin isosbestic point, was chosen. To avoid strong photoacoustic signal generation from the skin surface, we applied dark field illumination. To illuminate efficiently, we split the laser light into two beams, which were delivered to an animal by two mirrors and were finally homogenized by two ground glasses. To complete the dark field illumination, the transducer was located in the middle of two light sources. Two key devices for the in vivo imaging were rotating devices and animal holders. The rotating devices were composed of two parts, located at the top and bottom, which rotated at the same angular speed. The holders were composed of a head holder and a body holder. Both holders fixed the animal firmly to reduce motion artifacts. This system achieved radial resolution of up to 260\u03bcm. We accomplished successful in vivo imaging of arterial and venous vessels deeply, as well as superficially, with the animal head of up to 1.7cm diameter. The technique forms a basis for functional imaging, such as measurement of the oxygen consumption ratio in the brain, which is a vital parameter in a brain disease research.", "doi": "10.1117/12.646681", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60860Q" }, { "id": "authors:d4261-22446", "collection": "authors", "collection_id": "d4261-22446", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-083658039", "type": "book_section", "title": "Virtual-detector synthetic aperture focusing technique with application in in vivo photoacoustic microscopy", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "In this study, we introduce a synthetic aperture focusing technique which employs a virtual detector concept, combined with coherence weighting, to extend the depth of focus for an in-vivo photoacoustic microscopy system. This technique treats the transducer's focal point as a virtual point detector of photoacoustic signals, delays adjacent scan lines relative to the virtual detector, and then sums the delayed signals to achieve focusing in the out-of-focus region. In addition, a coherence factor among the delayed signals for each synthesized imaging point is used as a weighting factor to further improve the focusing quality. Images of an Intralipid phantom containing a carbon fiber show how this technique improves the -6 dB lateral resolution from 49-379 \u03bcm to 46-53 \u03bcm and increases the SNR by 0-29 dB, depending on the distance from the ultrasonic focal point. In vivo experiments show that this technique also provides a clearer tumorassociated angiogenesis in the mouse's scalp. The extended depth of focus for the photoacoustic microscopy system enables 3D reconstruction of the vascular network for the study of tumor angiogenesis.", "doi": "10.1117/12.645115", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60861F" }, { "id": "authors:a1ze0-mps74", "collection": "authors", "collection_id": "a1ze0-mps74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-084323302", "type": "book_section", "title": "Functional photoacoustic microscopy in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Oh", "given_name": "Jung-Taek", "clpid": "Oh-Jung-Taek" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Functional photoacoustic microscopy is a hybrid imaging technique that detects laser induced photoacoustic waves to image biological tissues in three dimensions. Its imaging depth exceeds the fundamental depth limit of the existing high resolution optical imaging modalities while maintaining a comparable ratio of imaging depth to axial resolution. The amplitude of photoacoutic waves is related to tissue's optical absorption and, therefore, functional imaging can be achieved by acquiring spectroscopic information. We demonstrate here the capabilities of functional photoacoustic microscopy by volumetric imaging a skin melanoma tumor and functional imaging of hemoglobin oxygen saturation in single vessels in vivo.", "doi": "10.1117/12.645143", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60861G" }, { "id": "authors:memws-nh639", "collection": "authors", "collection_id": "memws-nh639", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-111820114", "type": "book_section", "title": "Photoacoustic molecular imaging of small animals in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Oh", "given_name": "Jung-Taek", "clpid": "Oh-Jung-Taek" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Wei", "orcid": "0000-0002-5257-7675", "clpid": "Wang-Wei" }, { "family_name": "Li", "given_name": "Chun", "clpid": "Li-Chun" }, { "family_name": "Similache", "given_name": "Sergiu", "clpid": "Similache-S" }, { "family_name": "Lungu", "given_name": "Gina F.", "clpid": "Lungu-Gina-F" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Molecular imaging is a newly emerging field in which the modern tools of molecular and cell biology have been married to state-of-the-art technologies for noninvasive imaging. The study of molecular imaging will lead to better methods for understanding biological processes as well as diagnosing and managing disease. Here we present noninvasive in vivo spectroscopic photoacoustic tomography (PAT)-based molecular imaging of \u03b1v\u03b23 integrin in a nude mouse U87 brain tumor. PAT combines high optical absorption contrast and high ultrasonic resolution by employing short laser pulses to generate acoustic waves in biological tissues through thermoelastic expansion. Spectroscopic PAT-based molecular imaging offers the separation of the contributions from different absorbers based on the differences in optical absorption spectra among those absorbers. In our case, in the near infrared (NIR) range, oxy-heamoglobin (O2Hb), deoxy-heamoglobin (HHb) and the injected \u03b1v\u03b23-targeted peptide-ICG conjugated NIR fluorescent contrast agent are the three main absorbers. Therefore, with the excitation by multiple wavelength laser pulses, spectroscopic PAT-based molecular imaging not only provides the level of the contrast agent accumulation in the U87 glioblastoma tumor, which is related to the metabolism and angiogenesis of the tumor, but also offers the information on tumor angiogenesis and tumor hypoxia.", "doi": "10.1117/12.645121", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 608606" }, { "id": "authors:794rq-f6952", "collection": "authors", "collection_id": "794rq-f6952", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181026-111206518", "type": "book_section", "title": "Three-dimensional photoacoustic imaging of subcutaneous microvasculature in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zhang", "given_name": "Hao F.", "clpid": "Zhang-Hao-F" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Three-dimensional photoacoustic imaging of subcutaneous microvasculature in small animals is realized in vivo using photoacoustic microscopy. Previously, degraded lateral resolution in the out-of-focus region made three-dimensional visualization impractical. With the help of a virtual-detector synthetic aperture focusing technique, depth-independent lateral resolution is achieved. Therefore, volumetric imaging of the vessels is realized with a lateral resolution of 45 \u03bcm and an axial resolution of 15 \u03bcm. Detailed structural information, such as vessel depth and spatial orientation, are revealed with new clarity.", "doi": "10.1117/12.645138", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60861E" }, { "id": "authors:wjg89-tpc11", "collection": "authors", "collection_id": "wjg89-tpc11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181107-084753789", "type": "book_section", "title": "Fundamental considerations for multiwavelength photoacoustic molecular imaging", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Zemp", "given_name": "Roger J.", "clpid": "Zemp-R-J" }, { "family_name": "Li", "given_name": "Li", "clpid": "Li-Li" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic technology offers great promise for molecular imaging in vivo since it offers significant penetration, and optical contrast with ultrasonic spatial resolution. In this article we examine fundamental technical issues impacting capabilities of photoacoustic tomography for molecular imaging. First we examine how reconstructed photoacoustic tomography images are related to true absorber distributions by studying the modulation transfer function of a circular scanning tomographic system employing a modified filtered backprojection algorithm. We then study factors influencing quantitative estimation by developing a forward model of photoacoustic signal generation, and show conditions for which the system of equations can be inverted. Errors in the estimated optical fluence are shown to be a source of bias in estimates of molecular agent concentration. Finally we discuss noise propagation through the matrix inversion procedure and discuss implications for molecular imaging sensitivity and system design.", "doi": "10.1117/12.646392", "isbn": "9780819461285", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2006-03-06", "pages": "Art. No. 60861L" }, { "id": "authors:r8f3k-xgh16", "collection": "authors", "collection_id": "r8f3k-xgh16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-073142733", "type": "book_section", "title": "Functional photoacoustic tomography for non-invasive imaging of cerebral blood oxygenation and blood volume in rat brain in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Based on the multi-wavelength laser-based photoacoustic tomography, non-invasive in vivo imaging of functional parameters, including the hemoglobin oxygen saturation and the total concentration of hemoglobin, in small-animal brains was realized. The high sensitivity of this technique is based on the spectroscopic differences between oxy- and deoxy-hemoglobin while its spatial resolution is bandwidth-limited by the photoacoustic signals rather than by the optical diffusion as in optical imaging. The point-by-point distributions of blood oxygenation and blood volume in the cerebral cortical venous vessels, altered by systemic physiological modulations including hyperoxia, normoxia and hypoxia, were visualized successfully through the intact skin and skull. This technique, with its prominent intrinsic advantages, can potentially accelerate the progress in neuroscience and provide important new insights into cerebrovascular physiology and brain function that are of great significance to the neuroscience community.", "doi": "10.1117/12.589680", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "1-6" }, { "id": "authors:v9aqm-6ej06", "collection": "authors", "collection_id": "v9aqm-6ej06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-080326321", "type": "book_section", "title": "Photoacoustic tomography and molecular fluorescence imaging: dual modality imaging of small animal brains in vivo", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Oh", "given_name": "Jung-Taek", "clpid": "Oh-Jung-Taek" }, { "family_name": "Li", "given_name": "Meng-Lin", "clpid": "Li-Meng-Lin" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Ke", "given_name": "Shi", "clpid": "Ke-Shi" }, { "family_name": "Li", "given_name": "Chun", "clpid": "Li-Chun" }, { "family_name": "Similache", "given_name": "Sergiu", "clpid": "Similache-S" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present a dual modality imaging technique by combining photoacoustic tomography (PAT) and near-infrared (NIR) fluorescence imaging for the study of animal model tumors. PAT provides high-resolution structural images of tumor angiogenesis, and fluorescence imaging offers high sensitivity to molecular probes for tumor detection. Coregistration of the PAT and fluorescence images was performed on nude mice with M21 human melanoma cell lines with \u03b1v\u03b23 integrin expression. An integrin \u03b1v\u03b23-targeted peptide-ICG conjugated NIR fluorescent contrast agent was used as the molecular probe for tumor detection. PAT was employed to noninvasively image the brain structures and the angiogenesis associated with tumors in nude mice. Coregistration of the PAT and fluorescence images was used in this study to visualize tumor location, angiogenesis, and brain structure simultaneously.", "doi": "10.1117/12.589670", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "107-110" }, { "id": "authors:xzjgs-h3x04", "collection": "authors", "collection_id": "xzjgs-h3x04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-074540100", "type": "book_section", "title": "Breast cancer imaging by microwave-induced thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Xu", "given_name": "Minghua", "clpid": "Xu-Minghua" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Jin", "given_name": "Xing", "clpid": "Jin-Xing" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report a preliminary study of breast cancer imaging by microwave-induced thermoacoustic tomography. In this study, we built a prototype of breast cancer imager based on a circular scan mode. A 3-GHz 0.3~0.5-\u03bcs microwave is used as the excitation energy source. A 2.25-MHz ultrasound transducer scans the thermoacoustic signals. All the measured data is transferred to a personal computer for imaging based on our proposed back-projection reconstruction algorithms. We quantified the line spread function of the imaging system. It shows the spatial resolution of our experimental system reaches 0.5 mm. After phantom experiments demonstrated the principle of this technique, we moved the imaging system to the University of Texas MD Anderson Cancer Center to image the excised breast cancer specimens. After the surgery performed by the physicians at the Cancer Center, the excised breast specimen was placed in a plastic cylindrical container with a diameter of 10 cm; and it was then imaged by three imaging modalities: radiograph, ultrasound and thermoacoustic imaging. Four excised breast specimens have been tested. The tumor regions have been clearly located. This preliminary study demonstrated the potential of microwave-induced thermoacoustic tomography for applications in breast cancer imaging.", "doi": "10.1117/12.589128", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "45-48" }, { "id": "authors:z32a6-68113", "collection": "authors", "collection_id": "z32a6-68113", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-095953328", "type": "book_section", "title": "Analytical model for modulation of diffuse light by pulsed ultrasonic waves", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an analytical solution for the acousto-optical modulation of multiply scattered light in a medium irradiated with a train of ultrasound pulses. Previous theory is extended to cases where the ultrasound induced optical phase increments between the different scattering events are strongly correlated. The relation between the ultrasound induced motions of the fluid and the optical scatterers is generalized, and it is shown that correlation exists between the optical phase increments that are due to the scatterer movement and to the modulation of the optical index of refraction. Finally, it is shown that compared with the spectrum of the ultrasound pulses, the power spectral density of the acousto-optically modulated light is strongly attenuated toward the higher ultrasound frequencies.", "doi": "10.1117/12.589432", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "179-189" }, { "id": "authors:6fn88-9ph66", "collection": "authors", "collection_id": "6fn88-9ph66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-080928662", "type": "book_section", "title": "Deep penetrating photoacoustic tomography in biological tissues", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography (PAT) in a circular scanning configuration was developed to image the deeply embedded optical heterogeneity in biological tissues. Based on the intrinsic contrast between blood and chicken breast muscle, an embedded blood object that was 5 cm deep in the tissue was detected using pulsed laser light at a wavelength of 1064 nm. Compared with detectors for flat active surfaces, cylindrically focused ultrasonic transducers can reduce the interference generated from the off-plane photoacoustic sources and make the image in the scanning plane clearer. While the optical penetration was optimized with near-infrared laser pulses of 800 nm in wavelength, the optical contrast was enhanced by indocyanine green (ICG) whose absorption peak matched the laser wavelength. This optimized PAT was able to image fine objects embedded at a depth of up to 5.2-cm, which is 6.2 times the 1/e optical penetration depth, in chicken breast muscle, at a resolution of < ~750 microns with a sensitivity of <7 pmol of ICG in blood. The resolution was found to deteriorate slowly with increasing imaging depth.", "doi": "10.1117/12.588798", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "117-126" }, { "id": "authors:fmmdq-w6837", "collection": "authors", "collection_id": "fmmdq-w6837", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-110946396", "type": "book_section", "title": "Mitigating artifacts via half-time reconstruction in thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Anastasio", "given_name": "Mark A.", "orcid": "0000-0002-3192-4172", "clpid": "Anastasio-M-A" }, { "family_name": "Zhang", "given_name": "Jin", "clpid": "Zhang-Jin" }, { "family_name": "Pan", "given_name": "Xiaochuan", "clpid": "Pan-Xiaochuan" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Thermoacoustic tomography (TAT) is an ultrasound-mediated biophotonic imaging modality with great potential for a wide range of biomedical imaging applications. In this work, we demonstrate that half-time reconstruction approaches for TAT can mitigate image artifacts due to heterogeneous acoustic properties of an object. We also discuss how half-time reconstruction approaches permit explicit control of statistically complementary information in the measurement data, which can facilitate the reduction of image variances.", "doi": "10.1117/12.589190", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "263-270" }, { "id": "authors:hed4e-xja78", "collection": "authors", "collection_id": "hed4e-xja78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-074136300", "type": "book_section", "title": "High-resolution photoacoustic vascular imaging in vivo using a large-aperture acoustic lens", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Reflection-mode photoacoustic microscopy with dark-field laser pulse illumination and high frequency ultrasonic detection is used to non-invasively image blood vessels in the skin in vivo. Dark-field illumination minimizes the interference caused by strong photoacoustic signals from superficial structures. A high numerical-aperture acoustic lens provides high lateral resolution, 45-120 micrometers in this system while a broadband ultrasonic detection system provides high axial resolution, estimated to be ~15-20 micrometers. The optical illumination and ultrasonic detection are in a coaxial confocal configuration for optimal image quality. The system is capable of imaging optical-absorption contrast at up to 3 mm depth in biological tissue.", "doi": "10.1117/12.590558", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "7-14" }, { "id": "authors:sdrkd-be894", "collection": "authors", "collection_id": "sdrkd-be894", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181009-152712851", "type": "book_section", "title": "Universal back-projection algorithm for photoacoustic computed tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Xu", "given_name": "Minghua", "clpid": "Xu-Minghua" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We report a universal back-projection formula for three-dimensional photoacoustic computed tomography in three types of imaging geometries: planar, spherical, and cylindrical surfaces. A solid-angle weighting factor is introduced in the back-projection formula to compensate for the variations of detection views. Numerical simulation demonstrates the performance of the algorithm.", "doi": "10.1117/12.589146", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "251-254" }, { "id": "authors:dw7jp-81x92", "collection": "authors", "collection_id": "dw7jp-81x92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180926-095440592", "type": "book_section", "title": "Advances in high-resolution ultrasound-modulated optical tomography in biological tissues", "book_title": "Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an extension of our work on implementation of high-resolution ultrasound-modulated optical tomography that, based on optical contrast, can image several millimeters deep into soft biological tissues. A long-cavity confocal Fabry-Perot interferometer, which provides a large etendue and a short response time, was used to detect the ultrasound-modulated coherent light that traversed the scattering biological tissue. Using 15-MHz ultrasound, light absorbing structures placed >3 mm below the surface of chicken breast tissue were imaged with high contrast. The resolutions along the axial and lateral directions with respect to the ultrasound propagation direction were better than 70 um and 120 um, respectively. The resolutions can be scaled down further by using higher ultrasound frequencies. This technology is complementary to other imaging technologies, such as confocal microscopy and optical-coherence tomography, and has potential for broad biomedical applications.", "doi": "10.1117/12.589411", "isbn": "9780819456717", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2005-04-25", "pages": "174-178" }, { "id": "authors:kejwg-dsz58", "collection": "authors", "collection_id": "kejwg-dsz58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226623", "type": "book_section", "title": "Laser-induced photoacoustic tomography enhanced with an optical contrast agent", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Wegiel", "given_name": "Malgorzata A.", "clpid": "Wegiel-M-A" }, { "family_name": "Bornhop", "given_name": "Darryl J.", "clpid": "Bornhop-D-J" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Optical contrast agents, such as indocyanine dyes, nano-particles and their functional derivatives, have been widely applied to enhance the sensitivity and specificity of optical imaging. However, due to the overwhelming scattering of light in biological tissues, the spatial resolution of traditional optical imaging degrades drastically as the imaging depth increases. For the first time to our knowledge, non-invasive in vivo photoacoustic imaging of an optical contrast agent, distributed in the rat brain, was implemented with near-infrared light. Injection of indocyanine green polyethylene glycol, a contrast agent with a high absorption at the 805-nm wavelength, into the circulatory system of a rat enhanced the absorption contrast between the blood vessels and the background brain tissues. Because near-infrared light can penetrate deep into the brain tissues through the skin and skull, we were able to successfully reconstruct the vascular distribution in the rat brain from the detected photoacoustic signals. The dynamic concentration of this contrast agent in the brain blood after the intravenous injection was also studied. This work proved that the distribution of an exogenous contrast agent in biological tissues can be imaged clearly and accurately by photoacoustic tomography. This new technology has high potential for application in dynamic and molecular medical imaging.", "doi": "10.1117/12.532434", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "77-82" }, { "id": "authors:22byc-2bm58", "collection": "authors", "collection_id": "22byc-2bm58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226988", "type": "book_section", "title": "Application of time reversal to thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Xu", "given_name": "Yuan", "orcid": "0000-0001-9326-2197", "clpid": "Xu-Yuan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Reconstruction for thermoacoustic tomography in an arbitrary detection geometry is proposed by time-reversing the measured field back to the time when the thermoacoustic sources are excited. Time reversal of the field can be implemented efficiently by applying the delay-and-sum algorithm. The theoretical conclusions are supported by a numerical simulation of three-dimensional thermoacoustic tomography.", "doi": "10.1117/12.532395", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "257-263" }, { "id": "authors:8j7qt-t9j11", "collection": "authors", "collection_id": "8j7qt-t9j11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226532", "type": "book_section", "title": "Spatial resolution in three-dimensional photo-acoustic reconstruction", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Xu", "given_name": "Minghua", "clpid": "Xu-Minghua" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an analytic explanation of the spatial resolution in three-dimensional photo-acoustic (also called opto-acoustic or thermo-acoustic) reconstruction. Based on rigorous reconstruction formulas, we analytically derive the point-spread functions (PSFs) for three types of specific recording geometries, including spherical, planar, and cylindrical surfaces. The PSFs as a function of the bandwidth of the measurement system and the finite size of the detector aperture, as well as the discrete sampling effect on the reconstruction, are investigated. The analyses clearly reveal that the dependence of the PSFs on the bandwidth of all of the recording geometries shares the same space-invariant expression while the dependence on the aperture size of the detector differs. The bandwidth affects both axial and lateral resolution; in contrast, the detector aperture blurs the lateral resolution greatly but the axial resolution only slightly. Under-sampling in the measurement causes significant aliasing artifacts in the reconstruction. A general sampling strategy to avoid aliasing is proposed.", "doi": "10.1117/12.530475", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "264-267" }, { "id": "authors:7h46q-mtb49", "collection": "authors", "collection_id": "7h46q-mtb49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114227073", "type": "book_section", "title": "High-resolution imaging using ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Sakad\u017ei\u0107", "given_name": "Sava", "clpid": "Sakad\u017ei\u0107-S" }, { "family_name": "Maslov", "given_name": "Konstantin", "orcid": "0000-0003-3408-8840", "clpid": "Maslov-K-I" }, { "family_name": "Li", "given_name": "Jun", "clpid": "Li-Jun" }, { "family_name": "Kinra", "given_name": "Vikram K.", "clpid": "Kinra-V-K" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an implementation of ultrasound-modulated optical tomography that has the potential to provide high resolution images of tissue structures at a penetration depth of several millimeters. Light and pulsed ultrasound are focused on an approximately 100 \u03bcm wide area below the sample surface. With this configuration, the length of the ultrasonic pulses determines the axial resolution, and the lateral resolution results from the width of the ultrasonic beam at the focus. Diffuse light reflected from the sample is collected into a fiber and the modulated component is separated from the background by a confocal Fabry-Perot interferometer. Using this setup, high contrast images are obtained of 100 \u03bcm wide pieces of hair that are buried one millimeter below the surface of the tissue-mimicking sample. It is the first time, to the authors' knowledge, that images with such high resolution have been obtained using ultrasound-modulated optical tomography in the reflection mode.", "doi": "10.1117/12.530890", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "150-155" }, { "id": "authors:35mgg-fmt44", "collection": "authors", "collection_id": "35mgg-fmt44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226804", "type": "book_section", "title": "Photoacoustic tomography of rat brain in vivo using multibandwidth ultrasonic detection", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Photoacoustic tomography employs short laser pulses to generate acoustic waves. The photoacoustic image of a test sample can be reconstructed using the detected acoustic signals. The reconstructed image is characterized by the convolution of the sample structure in optical absorption, the laser pulse, and the impulse response of the ultrasonic transducer used for detection. Although laser-induced ultrasonic waves cover a wide spectral range, a single transducer can receive only part of the spectrum because of its limited bandwidth. To systematically analyze this problem, we constructed a photoacoustic tomographic system that uses multiple ultrasonic transducers, each at a different central frequency, to simultaneously receive the induced acoustic waves. The photoacoustic images associated with the different transducers were compared and analyzed. The system was used to detect the vascular system of the rat brain. The vascular vessels in the brain cortex were revealed by all of the transducers, but the image resolutions differed. The higher frequency detectors with wider bandwidths provided better image resolution.", "doi": "10.1117/12.532195", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "172-178" }, { "id": "authors:v24vh-fm583", "collection": "authors", "collection_id": "v24vh-fm583", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114227162", "type": "book_section", "title": "Acousto-electric tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Zhang", "given_name": "Hao", "clpid": "Zhang-Hao" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Although the electric impedance of biological tissues is highly sensitive to their physiological and pathological status, pure electrical impedance tomography (EIT) has very poor spatial resolution. We invented acousto-electric tomography (AET) to image the electric impedance properties of biological tissues with high spatial resolution. AET is based on acousto-electric modulation, which is the localized variation in conductivity produced by a focused ultrasonic wave. It combines the contrast advantage of EIT and the resolution advantage of ultrasound imaging. The spatial resolution of AET is primarily defined by the size of the ultrasonic focal spot. Therefore, the resolution is much better than that of EIT, and it is scalable with the acoustic parameters. The contrast of AET is determined by the combination of three factors: the electric impedance, the media dependent modulation coefficient, and the acoustic properties. Unlike EIT, AET forms images directly without resorting to inverse algorithms. And unlike traditional ultrasonography, AET is free of speckles.", "doi": "10.1117/12.532610", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "145-149" }, { "id": "authors:vta87-ktq50", "collection": "authors", "collection_id": "vta87-ktq50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114227252", "type": "book_section", "title": "Non-invasive functional photoacoustic tomography of blood-oxygen saturation in the brain", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Wang", "given_name": "Xueding", "clpid": "Wang-Xueding" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Xie", "given_name": "Xueyi", "clpid": "Xie-Xueyi" }, { "family_name": "Wang", "given_name": "Yiwen", "clpid": "Wang-Yiwen" }, { "family_name": "Stoica", "given_name": "George", "orcid": "0000-0001-8071-4828", "clpid": "Stoica-G" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Since optical contrast is sensitive to functional parameters, including the hemoglobin oxygen saturation and the total concentration of hemoglobin, imaging based on optical contrast has been widely employed for the real-time monitoring of tissue oxygen consumption and hemodynamics in biological tissues. However, due to the overwhelming scattering of light in tissues, traditional optical imaging modalities cannot provide satisfactory spatial resolution. Functional photoacoustic tomography is a novel technique that combines high optical contrast and high ultrasonic resolution. Here, we present our study of a laser-based photoacoustic technique that, for the first time to our knowledge, monitors blood oxygenation in the rat brain in vivo. The cerebral blood oxygenation in the rat brain was imaged by photoacoustic detection at two wavelengths. The change in the hemoglobin oxygen saturation in the brain vessels as a result of the alternation from hyperoxia status to hypoxia status was visualized successfully with satisfactory spatial resolution. This work demonstrates that photoacoustic technique, based on the spectroscopic absorption of oxy- and deoxy-hemoglobin, can provide accurate functional imaging of cerebral blood oxygenation in the small-animal brain non-invasively with the skin and skull intact.", "doi": "10.1117/12.532440", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "69-76" }, { "id": "authors:eh8nn-6m184", "collection": "authors", "collection_id": "eh8nn-6m184", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226717", "type": "book_section", "title": "Signal and noise in ultrasound-modulated optical tomography: a Monte Carlo study", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Yao", "given_name": "Gang", "clpid": "Yao-Gang" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "Ultrasound-modulated optical tomography in inhomogeneous scattering media was studied using a Monte Carlo modeling technique. The contributions from two different modulation mechanisms were included in the simulation. The differences between embedded absorption and scattering objects in the ultrasound-modulated optical signals were compared. The effects of neighboring inhomogeneity and background optical properties on the ultrasound-modulated optical signals were also studied. We analyzed the signal-to-noise ratio in the experiment and found that the major noise source is the speckle noise caused by small particle movement within the biological tissue sample. This effect was studied by incorporating a Brownian motion factor in the simulation.", "doi": "10.1117/12.532847", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "156-163" }, { "id": "authors:n845g-9eg81", "collection": "authors", "collection_id": "n845g-9eg81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114226895", "type": "book_section", "title": "Image reconstruction in ultrasound-modulated optical tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Li", "given_name": "Jun", "clpid": "Li-Jun" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "We present an image reconstruction technique for ultrasound-modulated optical tomography. It is the first time, to the authors' knowledge, that a reconstruction technique is developed for such tomography. In analogy to X-ray computed tomography, an ultrasonic beam is scanned linearly and angularly across a biological-tissue sample. Ultrasound-modulated optical signals, reflecting the optical properties of the sample inside the ultrasonic column, are detected and taken as the projection data for the reconstruction, where a filtered back-projection algorithm is implemented. With the technique, two-dimensional images of biological tissues in cross-sections containing the scanned ultrasonic axis are obtained. The image resolution is determined by the diameter of the ultrasonic focal zone. The technique can be implemented with any standard signal-detection scheme for ultrasonic modulation of coherent light in scattering media and can be applied directly to achieve three-dimensional images of biological tissues.", "doi": "10.1117/12.530537", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "268-272" }, { "id": "authors:z0j7k-p6m63", "collection": "authors", "collection_id": "z0j7k-p6m63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-114227370", "type": "book_section", "title": "Visualization of HIFU-induced lesions with thermoacoustic tomography", "book_title": "Photons Plus Ultrasound: Imaging and Sensing", "author": [ { "family_name": "Jin", "given_name": "Xing", "clpid": "Jin-Xing" }, { "family_name": "Xu", "given_name": "Yuan", "orcid": "0000-0001-9326-2197", "clpid": "Xu-Yuan" }, { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Zanelli", "given_name": "Claudio I.", "clpid": "Zanelli-C-I" }, { "family_name": "Howard", "given_name": "Samuel M.", "clpid": "Howard-S-M" }, { "family_name": "Fang", "given_name": "Yuncai", "clpid": "Fang-Yuncai-R" } ], "contributor": [ { "family_name": "Oraevsky", "given_name": "Alexander A.", "clpid": "Oraevsky-A-A" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" } ], "abstract": "High-intensity focused ultrasound (HIFU) has proved to be an effective minimally invasive surgical technology. In this study, we focus on the visualization of HIFU-induced lesions using microwave-induced thermoacoustic tomography (TAT). TAT has high spatial resolution, comparable with ultrasound imaging, and high contrast, which is induced by differences in the microwave absorption rates between tumor tissue and normal tissue. TAT can, in addition, differentiate tumors before and after treatment. A single, spherically focused transducer operating at a center frequency of approximately 4 MHZ was used to generate the focused field. The lesion was generated in porcine muscle. A local-tomography-type reconstruction algorithm was applied to reconstruct the TAT image of the lesions. The lesion shown by gross pathology confirms the corresponding region measured by TAT.", "doi": "10.1117/12.532359", "isbn": "9780819452283", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2004-07-12", "pages": "40-43" }, { "id": "authors:vw56j-5hz68", "collection": "authors", "collection_id": "vw56j-5hz68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181207-161548152", "type": "book_section", "title": "Combining sound and light in scattering media", "book_title": "1999 International Conference on Biomedical Optics", "author": [ { "family_name": "Wang", "given_name": "Lihong V.", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong-V" }, { "family_name": "Ku", "given_name": "Geng", "clpid": "Ku-Geng" }, { "family_name": "Shen", "given_name": "Qimin", "clpid": "Shen-Qimin" } ], "contributor": [ { "family_name": "Luo", "given_name": "Qingming", "clpid": "Luo-Qingming" }, { "family_name": "Chance", "given_name": "Britton", "clpid": "Chance-B" }, { "family_name": "Wang", "given_name": "Lihong V.", "clpid": "Wang-Lihong-V" }, { "family_name": "Jacques", "given_name": "Steven L.", "clpid": "Jacques-S-L" } ], "abstract": "Two imaging techniques combining ultrasound and light are reviewed. The motivation is to combine the advantages of optical information and acoustic imaging resolution. The first technique is sonoluminescence tomography, where a sonoluminescence signal generated internally in the media by continuous-wave ultrasound is used. 2D images can be produced for objects embedded in turbid media by raster scanning the media. The second technique is ultrasound-modulated optical tomography, where a frequency-swept ultrasonic wave was used to modulate the laser light passing through a scattering medium. Multiple 1D images obtained at various positions perpendicular to the ultrasonic axis were composed to obtain a 2D tomographic image of the medium.", "doi": "10.1117/12.364370", "isbn": "9780819434555", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1999-09-17", "pages": "95-104" } ]