951
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Li L, Zhang HF, Zemp RJ, Maslov K, Wang L. Simultaneous imaging of a lacZ-marked tumor and microvasculature morphology in vivo by dual-wavelength photoacoustic microscopy. JOURNAL OF INNOVATIVE OPTICAL HEALTH SCIENCES 2008; 1:207-215. [PMID: 19946613 PMCID: PMC2782593 DOI: 10.1142/s1793545808000212] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Photoacoustic molecular imaging, combined with the reporter-gene technique, can provide a valuable tool for cancer research. The expression of the lacZ reporter gene can be imaged using photoacoustic imaging following the injection of X-gal, a colorimetric assay for the lacZ-encoded enzyme β-galactosidase. Dual-wavelength photoacoustic microscopy was used to non-invasively image the detailed morphology of a lacZ-marked 9L gliosarcoma and its surrounding microvasculature simultaneously in vivo, with a superior resolution on the order of 10 μm. Tumor-feeding vessels were found, and the expression level of lacZ in tumor was estimated. With future development of new absorption-enhancing reporter-gene systems, we anticipate this strategy can lead to a better understanding of the role of tumor metabolism in cancer initiation, progression, and metastasis, and in its response to therapy.
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Affiliation(s)
- Li Li
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA 63130
| | - Hao F. Zhang
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA 63130
- Now with Department of Electrical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA 53201
| | - Roger J. Zemp
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA 63130
- Now with Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G2V4
| | - Konstantin Maslov
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA 63130
| | - Lihong Wang
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA 63130
- Corresponding author.
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952
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Zhang C, Wang Y. Deconvolution reconstruction of full-view and limited-view photoacoustic tomography: a simulation study. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2008; 25:2436-2443. [PMID: 18830321 DOI: 10.1364/josaa.25.002436] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Although many algorithms are available for full-view photoacoustic tomography (PAT), no exact and stable algorithm for limited-view PAT has been proposed. In this paper the deconvolution reconstruction (DR) algorithm is proposed for both full-view and limited-view PAT. In the DR algorithm, first a new function is constructed from detected photoacoustic signals and approximately simplified, and then the tissue's electromagnetic absorption is derived from this function on the basis of Fourier-based deconvolution. Computer simulations are carried out to compare the DR algorithm with two popular PAT algorithms, the time-domain reconstruction (TDR) and the filtered back projection (FBP). Although the error of the DR algorithm increases with the size of the detected object, it is shown that the DR algorithm has good precision and strong robustness to noise in the full-view PAT, nearly equivalent to the TDR and FBP. Yet the DR algorithm is more than ten times faster in computation speed. In the limited-view PAT, the DR is superior to the TDR and FBP in terms of both accuracy and robustness to noise.
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Affiliation(s)
- Chi Zhang
- Department of Electronic Engineering, Fudan University, Shanghai, China
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953
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Debbage P, Jaschke W. Molecular imaging with nanoparticles: giant roles for dwarf actors. Histochem Cell Biol 2008; 130:845-75. [PMID: 18825403 DOI: 10.1007/s00418-008-0511-y] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2008] [Indexed: 10/25/2022]
Abstract
Molecular imaging, first developed to localise antigens in light microscopy, now encompasses all imaging modalities including those used in clinical care: optical imaging, nuclear medical imaging, ultrasound imaging, CT, MRI, and photoacoustic imaging. Molecular imaging always requires accumulation of contrast agent in the target site, often achieved most efficiently by steering nanoparticles containing contrast agent into the target. This entails accessing target molecules hidden behind tissue barriers, necessitating the use of targeting groups. For imaging modalities with low sensitivity, nanoparticles bearing multiple contrast groups provide signal amplification. The same nanoparticles can in principle deliver both contrast medium and drug, allowing monitoring of biodistribution and therapeutic activity simultaneously (theranostics). Nanoparticles with multiple bioadhesive sites for target recognition and binding will be larger than 20 nm diameter. They share functionalities with many subcellular organelles (ribosomes, proteasomes, ion channels, and transport vesicles) and are of similar sizes. The materials used to synthesise nanoparticles include natural proteins and polymers, artificial polymers, dendrimers, fullerenes and other carbon-based structures, lipid-water micelles, viral capsids, metals, metal oxides, and ceramics. Signal generators incorporated into nanoparticles include iron oxide, gadolinium, fluorine, iodine, bismuth, radionuclides, quantum dots, and metal nanoclusters. Diagnostic imaging applications, now appearing, include sentinal node localisation and stem cell tracking.
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Affiliation(s)
- Paul Debbage
- Department of Anatomy, Division of Histology and Embryology, Medical University Innsbruck, Muellerstrasse 59, 6020, Innsbruck, Austria.
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954
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Kolkman RGM, Mulder MJ, Glade CP, Steenbergen W, van Leeuwen TG. Photoacoustic imaging of port-wine stains. Lasers Surg Med 2008; 40:178-82. [PMID: 18366079 DOI: 10.1002/lsm.20612] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND AND OBJECTIVE To optimize laser therapy of port-wine stains (PWSs), information about the vasculature as well as lesion depth is valuable. In this study we investigated the use of photoacoustic imaging (PAI) to obtain this information. STUDY DESIGN/MATERIALS AND METHODS PAI uses pulsed light to generate ultrasound upon absorption of short light pulses by blood. In this study we used PAI to image vasculature in PWSs in three human volunteers. Two-dimensional imaging (scan direction vs. depth) was carried out by scanning a double-ring photoacoustic sensor over the tissue surface. RESULTS In the photoacoustic images we observed an increased photoacoustic signal intensity at the locations of the PWS that is associated with increased vascularization. From the obtained images we measured the thickness of the vascular layer and estimated lesion depth. In some cases single vessels could be observed at the position of the PWS whereas in other cases the PWS appeared as a region with large photoacoustic signal intensity. CONCLUSIONS PAI has the potential to reveal information about the lesion depth as well as thickness of the vascular layer.
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Affiliation(s)
- Roy G M Kolkman
- Biophysical Engineering, Institute for BioMedical Technology, Faculty of Science & Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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955
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Song KH, Stein EW, Margenthaler JA, Wang LV. Noninvasive photoacoustic identification of sentinel lymph nodes containing methylene blue in vivo in a rat model. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054033. [PMID: 19021413 PMCID: PMC2725003 DOI: 10.1117/1.2976427] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Sentinel lymph node biopsy (SLNB) has become the standard method of axillary staging for patients with breast cancer and clinically negative axillae. 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. Axillary ultrasound has emerged as a diagnostic tool to evaluate the axilla, but it can only assess morphology and cannot specifically identify sentinel lymph nodes (SLNs). In this pilot study, we propose a noninvasive photoacoustic SLN identification system using methylene blue injection in a rat model. We successfully image a SLN with high optical contrast (146+/-41, standard deviation) and good ultrasonic resolution (approximately 500 microm) in vivo. We also show potential feasibility for clinical applications by imaging 20- and 31-mm-deep SLNs in 3-D and 2-D, respectively. Our results suggest that this technology would be a useful clinical tool, allowing clinicians to identify SLNs noninvasively in vivo.
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Affiliation(s)
- Kwang Hyun Song
- Washington University in Saint Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, Campus Box 1097, One Brookings Drive, Saint Louis, Missouri 63130-4899, USA
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956
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Ephrat P, Keenliside L, Seabrook A, Prato FS, Carson JJL. Three-dimensional photoacoustic imaging by sparse-array detection and iterative image reconstruction. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054052. [PMID: 19021432 DOI: 10.1117/1.2992131] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Photoacoustic imaging (PAI) has the potential to acquire 3-D optical images at high speed. Attempts at 3-D photoacoustic imaging have used a dense 2-D array of ultrasound detectors or have densely scanned a single detector on a 2-D surface. The former approach is costly and complicated to realize, while the latter is inherently slow. We present a different approach based on a sparse 2-D array of detector elements and an iterative reconstruction algorithm. This approach has the potential for fast image acquisition, since no mechanical scanning is required, and for simple and compact construction due to the smaller number of detector elements. We obtained spatial sensitivity maps of the sparse array and used them to optimize the image reconstruction algorithm. We then validated the method on phantoms containing 3-D distributions of optically absorbing point sources. Reconstruction of the point sources from the time-domain signals resulted in images with good contrast and accurate localization (< or =1 mm error). Image acquisition time was 1 s. The results suggest that 3-D PAI with a sparse array of detector elements is a viable approach. Furthermore, the rapid acquisition speed indicates the possibility of high frame rate 3-D PAI.
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Affiliation(s)
- Pinhas Ephrat
- Lawson Health Research Institute, Imaging Program, London, Ontario N6A 4V2, Canada
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957
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DE LA ZERDA ADAM, ZAVALETA CRISTINA, KEREN SHAY, VAITHILINGAM SRIKANT, BODAPATI SUNIL, LIU ZHUANG, LEVI JELENA, SMITH BRYANR, MA TEJEN, ORALKAN OMER, CHENG ZHEN, CHEN XIAOYUAN, DAI HONGJIE, KHURI-YAKUB BUTRUST, GAMBHIR SANJIVS. Carbon nanotubes as photoacoustic molecular imaging agents in living mice. NATURE NANOTECHNOLOGY 2008; 3:557-62. [PMID: 18772918 PMCID: PMC2562547 DOI: 10.1038/nnano.2008.231] [Citation(s) in RCA: 788] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 07/04/2008] [Indexed: 05/18/2023]
Abstract
Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects.
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Affiliation(s)
- ADAM DE LA ZERDA
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
- Department of Electrical Engineering, Stanford University, Palo Alto, California 94305, USA
| | - CRISTINA ZAVALETA
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - SHAY KEREN
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - SRIKANT VAITHILINGAM
- Department of Electrical Engineering, Stanford University, Palo Alto, California 94305, USA
| | - SUNIL BODAPATI
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - ZHUANG LIU
- Department of Chemistry, Stanford University, Palo Alto, California 94305, USA
| | - JELENA LEVI
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - BRYAN R. SMITH
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - TE-JEN MA
- Department of Electrical Engineering, Stanford University, Palo Alto, California 94305, USA
| | - OMER ORALKAN
- Department of Electrical Engineering, Stanford University, Palo Alto, California 94305, USA
| | - ZHEN CHENG
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - XIAOYUAN CHEN
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
| | - HONGJIE DAI
- Department of Chemistry, Stanford University, Palo Alto, California 94305, USA
| | - BUTRUS T. KHURI-YAKUB
- Department of Electrical Engineering, Stanford University, Palo Alto, California 94305, USA
| | - SANJIV S. GAMBHIR
- Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University, Palo Alto, California 94305, USA
- Department of Bioengineering, Stanford University, Palo Alto, California 94305, USA
- e-mail:
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958
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Abstract
We demonstrate that microscopic imaging is feasible in ultrasound-modulated optical tomography (UOT) of soft biological tissues, using a high-frequency focused ultrasound transducer with a 75-MHz central frequency. Our experiments in tissue mimicking phantoms show that at an imaging depth of about 2 mm, an axial resolution better than 30 microm can be achieved, whereas the lateral resolution is 38 microm. A long-cavity scanning confocal Fabry-Perot interferometer (CFPI) is used for real-time detection of multiply scattered light modulated by high-frequency ultrasound pulses propagating in an optically scattering medium. We also compare the performances of various high-frequency focused ultrasound transducers with central frequencies of 15 MHz, 30 MHz, 50 MHz, and 75 MHz. The comparison is based on two-dimensional (2-D) images of optically absorbing objects positioned at a few millimeters depth below the surface of both optically scattering phantoms and soft biological tissue samples. Our experimental results show that modulation depth and image contrast decrease with an increase in ultrasound frequency. In addition, we use analytical calculations to show that modulation depth decreases with increasing ultrasound frequency.
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959
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Song L, Maslov K, Bitton R, Shung KK, Wang LV. Fast 3-D dark-field reflection-mode photoacoustic microscopy in vivo with a 30-MHz ultrasound linear array. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054028. [PMID: 19021408 PMCID: PMC2644744 DOI: 10.1117/1.2976141] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present an in vivo dark-field reflection-mode photoacoustic microscopy system that performs cross-sectional (B-scan) imaging at 50 Hz with real-time beamforming and 3-D imaging consisting of 166 B-scan frames at 1 Hz with postbeamforming. To our knowledge, this speed is currently the fastest in photoacoustic imaging. A custom-designed light delivery system is integrated with a 30-MHz ultrasound linear array to realize dark-field reflection-mode imaging. Linear mechanical scanning of the array produces 3-D images. The system has axial, lateral, and elevational resolutions of 25, 70, and 200 microm, respectively, and can image 3 mm deep in scattering biological tissues. Volumetric images of subcutaneous vasculature in rats are demonstrated in vivo. Fast 3-D photoacoustic microscopy is anticipated to facilitate applications of photoacoustic imaging in biomedical studies that involve dynamics and clinical procedures that demand immediate diagnosis.
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Affiliation(s)
- Liang Song
- Washington University in St. Louis, Optical Imaging Laboratory, Department of Biomedical Engineering, St. Louis, Missouri 63130, USA
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960
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Zhang C, Wang Y. A reconstruction algorithm for thermoacoustic tomography with compensation for acoustic speed heterogeneity. Phys Med Biol 2008; 53:4971-82. [PMID: 18711251 DOI: 10.1088/0031-9155/53/18/008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An inverse reconstruction algorithm for thermoacoustic tomography (TAT) is proposed with the compensation for the acoustic speed heterogeneity. Not requiring the prior knowledge of the acoustic speed distribution like most other algorithms, this algorithm utilizes the correlation information between thermoacoustic signals to compensate for the acoustic heterogeneity. The absorbed energy density is reconstructed on the basis of a corrected time-domain formula. Computer simulations are carried out to validate the algorithm. It is shown that the algorithm has a good precision within the acoustic speed variation of 10%, strong robustness to random data noises and good computational efficiency compared to other model-based methods. Therefore, the algorithm may be used in TAT of biological soft tissues, in which the acoustic speed variation is normally within 10%.
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Affiliation(s)
- Chi Zhang
- Department of Electronic Engineering, Fudan University, Shanghai 200433, People's Republic of China
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961
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Hendee WR, Cleary K, Ehman RL, Fullerton GD, Grundfest WS, Haller J, Kelley CA, Meyer AE, Murphy RF, Phillips W, Torchilin VP. Bioengineering and imaging research opportunities workshop V: summary of findings on imaging and characterizing structure and function in native and engineered tissues. Radiology 2008; 248:342-7. [PMID: 18641242 DOI: 10.1148/radiol.2482080456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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962
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Lao Y, Xing D, Yang S, Xiang L. Noninvasive photoacoustic imaging of the developing vasculature during early tumor growth. Phys Med Biol 2008; 53:4203-12. [PMID: 18635896 DOI: 10.1088/0031-9155/53/15/013] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this study, we monitor the progress of vasculature in early tumor growth using photoacoustic imaging over a 20 day period after subcutaneous inoculation of breast cancer tumor cells in a mouse. With 532 nm laser pulses employed as an irradiation source, the photoacoustic images were obtained through the photoacoustic signals received by a hydrophone in orthogonal mode. The morphological characteristics of vasculature in tumor region are clearly resolved in the photoacoustic images, and the change in structure as well as the increase in density can be identified. Moreover, the average photoacoustic signal strength of vasculature in tumor region, which is highly correlated with the total hemoglobin concentration of blood, is enhanced during early tumor growth. These results indicate the feasibility of detecting early stage tumor and monitoring the progress of anti-angiogenic therapy by photoacoustic imaging.
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Affiliation(s)
- Yeqi Lao
- MOE Key Laboratory of Laser Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
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963
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Bioengineering and Imaging Research Opportunities Workshop V: A Summary. Ann Biomed Eng 2008; 36:1315-21. [DOI: 10.1007/s10439-008-9529-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2008] [Accepted: 06/18/2008] [Indexed: 11/26/2022]
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964
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Hendee W, Cleary K, Ehman R, Fullerton G, Grundfest W, Haller J, Kelley C, Meyer A, Murphy RF, Phillips W, Torchilin V. Bioengineering and Imaging Research Opportunities Workshop V: A white paper on imaging and characterizing structure and function in native and engineered tissues. Med Phys 2008; 35:3428-35. [DOI: 10.1118/1.2948317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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965
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Meinhardt M, Krebs R, Anders A, Heinrich U, Tronnier H. Wavelength-dependent penetration depths of ultraviolet radiation in human skin. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:044030. [PMID: 19021357 DOI: 10.1117/1.2957970] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The wavelength-dependent penetration depth of ultraviolet radiation in human skin is a fundamental parameter for the estimation of the possible photobiological impact of ultraviolet (UV) radiation. We have determined the absorption spectra of human skin in vivo in the wavelength range from 290 to 341 nm in 3-nm steps using laser optoacoustics and calculated the respective penetration depths. Data were analyzed with respect to different skin regions and skin phototype of the 20 subjects in the study (phototype I: n=3; II: n=7; III: n=5; IV: n=5), revealing large variability between individuals. The penetration depth of UV radiation in human skin is highly dependent on wavelength and skin area, but no significant dependence on skin phototype could be found.
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Affiliation(s)
- Merve Meinhardt
- Leibniz University Hannover, Institute of Biophysics, Herrenhaeuser Str. 2, D-30419 Hannover, Germany.
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966
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Zemp RJ, Song L, Bitton R, Shung KK, Wang LV. Realtime photoacoustic microscopy in vivo with a 30-MHz ultrasound array transducer. OPTICS EXPRESS 2008; 16:7915-28. [PMID: 18545502 PMCID: PMC2717902 DOI: 10.1364/oe.16.007915] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present a novel high-frequency photoacoustic microscopy system capable of imaging the microvasculature of living subjects in realtime to depths of a few mm. The system consists of a high-repetition-rate Q-switched pump laser, a tunable dye laser, a 30-MHz linear ultrasound array transducer, a multichannel high-frequency data acquisition system, and a shared-RAM multi-core-processor computer. Data acquisition, beamforming, scan conversion, and display are implemented in realtime at 50 frames per second. Clearly resolvable images of 6-microm-diameter carbon fibers are experimentally demonstrated at 80 microm separation distances. Realtime imaging performance is demonstrated on phantoms and in vivo with absorbing structures identified to depths of 2.5-3 mm. This work represents the first high-frequency realtime photoacoustic imaging system to our knowledge.
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Affiliation(s)
- Roger J. Zemp
- Washington University, Optical Imaging Laboratory, Department of Biomedical Engineering, Saint Louis, Missouri 63130
| | - Liang Song
- Washington University, Optical Imaging Laboratory, Department of Biomedical Engineering, Saint Louis, Missouri 63130
| | - Rachel Bitton
- University of Southern California, Department of Biomedical Engineering, Los Angeles, California 90089
| | - K. Kirk Shung
- University of Southern California, Department of Biomedical Engineering, Los Angeles, California 90089
| | - Lihong V. Wang
- Washington University, Optical Imaging Laboratory, Department of Biomedical Engineering, Saint Louis, Missouri 63130
- Corresponding author:
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967
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Maslov K, Zhang HF, Hu S, Wang LV. Optical-resolution photoacoustic microscopy for in vivo imaging of single capillaries. OPTICS LETTERS 2008; 33:929-31. [PMID: 18451942 DOI: 10.1364/ol.33.000929] [Citation(s) in RCA: 374] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Capillaries, the smallest blood vessels, are the distal end of the vasculature where oxygen and nutrients are exchanged between blood and tissue. Hence, noninvasive imaging of capillaries and function in vivo has long been desired as a window to studying fundamental physiology, such as neurovascular coupling. Existing imaging modalities cannot provide the required sensitivity and spatial resolution. We present in vivo imaging of the microvasculature including single capillaries in mice using optical-resolution photoacoustic microscopy (OR-PAM) developed in our laboratory. OR-PAM provides a lateral resolution of 5 microm and an imaging depth >0.7 mm.
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Affiliation(s)
- Konstantin Maslov
- Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
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968
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Abstract
New technologies for imaging molecules, particularly optical technologies, are increasingly being used to understand the complexity, diversity and in vivo behaviour of cancers. 'Omic' approaches are providing comprehensive 'snapshots' of biological indicators, or biomarkers, of cancer, but imaging can take this information a step further, showing the activity of these markers in vivo and how their location changes over time. Advances in experimental and clinical imaging are likely to improve how cancer is understood at a systems level and, ultimately, should enable doctors not only to locate tumours but also to assess the activity of the biological processes within these tumours and to provide 'on the spot' treatment.
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Affiliation(s)
- Ralph Weissleder
- Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 5206, Boston, Massachusetts 02114, USA
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969
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Chamberland DL, Agarwal A, Kotov N, Brian Fowlkes J, Carson PL, Wang X. Photoacoustic tomography of joints aided by an Etanercept-conjugated gold nanoparticle contrast agent-an ex vivo preliminary rat study. NANOTECHNOLOGY 2008; 19:095101. [PMID: 21817663 DOI: 10.1088/0957-4484/19/9/095101] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Monitoring of anti-rheumatic drug delivery in experimental models and in human diseases would undoubtedly be very helpful for both basic research and clinical management of inflammatory diseases. In this study, we have investigated the potential of an emerging hybrid imaging technology-photoacoustic tomography-in noninvasive monitoring of anti-TNF drug delivery. After the contrast agent composed of gold nanorods conjugated with Etanercept molecules was produced, ELISA experiments were performed to prove the conjugation and to show that the conjugated anti-TNF-α drug was biologically active. PAT of ex vivo rat tail joints with the joint connective tissue enhanced by intra-articularly injected contrast agent was conducted to examine the performance of PAT in visualizing the distribution of the gold-nanorod-conjugated drug in articular tissues. By using the described system, gold nanorods with a concentration down to 1 pM in phantoms or 10 pM in biological tissues can be imaged with good signal-to-noise ratio and high spatial resolution. This study demonstrates the feasibility of conjugating TNF antagonist pharmaceutical preparations with gold nanorods, preservation of the mechanism of action of TNF antagonist along with preliminary evaluation of novel PAT technology in imaging optical contrast agents conjugated with anti-rheumatic drugs. Further in vivo studies on animals are warranted to test the specific binding between such conjugates and targeted antigen in joint tissues affected by inflammation.
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970
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Gamelin J, Aguirre A, Maurudis A, Huang F, Castillo D, Wang LV, Zhu Q. Curved array photoacoustic tomographic system for small animal imaging. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:024007. [PMID: 18465970 PMCID: PMC2507725 DOI: 10.1117/1.2907157] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present systematic characterization of a photoacoustic imaging system optimized for rapid, high-resolution tomographic imaging of small animals. The system is based on a 128-element ultrasonic transducer array with a 5-MHz center frequency and 80% bandwidth shaped to a quarter circle of 25 mm radius. A 16-channel data-acquisition module and dedicated channel detection electronics enable capture of a 90-deg field-of-view image in less than 1 s and a complete 360-deg scan using sample rotation within 15 s. Measurements on cylindrical phantom targets demonstrate a resolution of better than 200 microm and high-sensitivity detection of 580-microm blood tubing to depths greater than 3 cm in a turbid medium with reduced scattering coefficient mu(s) (')=7.8 cm(-1). The system is used to systematically investigate the effects of target size, orientation, and geometry on tomographic imaging. As a demonstration of these effects and the system imaging capabilities, we present tomographic photoacoustic images of the brain vasculature of an ex vivo mouse with varying measurement aperture. For the first time, according to our knowledge, resolution of sub-200-microm vessels with an overlying turbid medium of greater than 2 cm depth is demonstrated using only intrinsic biological contrast.
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Affiliation(s)
- John Gamelin
- University of Connecticut, Department of Electrical Engineering, Storrs, Connecticut 06269, USA.
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971
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Maslov K, Wang LV. Photoacoustic imaging of biological tissue with intensity-modulated continuous-wave laser. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:024006. [PMID: 18465969 DOI: 10.1117/1.2904965] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We build a photoacoustic imaging system using an intensity-modulated continuous-wave laser source, which is an inexpensive, compact, and durable 120-mW laser diode. The goal is to significantly reduce the costs and sizes of photoacoustic imaging systems. By using a bowl-shaped piezoelectric transducer, whose numerical aperture is 0.85 and resonance frequency is 2.45 MHz, we image biological tissues with a lateral resolution of 0.45 mm, an axial resolution of 1 mm, and an SNR as high as 43 dB.
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Affiliation(s)
- Konstantin Maslov
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, Campus Box 1097, One Brookings Drive, St. Louis, Missouri 63130-4899, USA
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972
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Levenson RM, Lynch DT, Kobayashi H, Backer JM, Backer MV. Multiplexing with Multispectral Imaging: From Mice to Microscopy. ILAR J 2008; 49:78-88. [DOI: 10.1093/ilar.49.1.78] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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973
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Chamberland DL, Wang X, Roessler BJ. Photoacoustic tomography of carrageenan-induced arthritis in a rat model. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:011005. [PMID: 18315354 DOI: 10.1117/1.2841028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Laser-based photoacoustic tomography (PAT), a novel, nonionizing, noninvasive, laser-based technology, has been adapted to the diagnosis and imaging of inflammatory arthritis. A commonly used adjuvant induced arthritis model using carrageenan was employed to simulate acute rheumatoid arthritis in rat tail joints. Cross-sectional photoacoustic images of joints affected by acute inflammation were compared to those of the control. The diameter of the periosteum and the optical absorption of intra-articular tissue were measured on each joint image. Significant differences were found on PAT imaging between the affected joints and the control for both variables measured, including enlarged periosteum diameter and enhanced intra-articular optical absorption occurring in the joints affected with carrageenan-induced arthritis. Anatomical correlation with histological sections of imaged joints and microMRI results verified the findings of PAT. This suggests that PAT has the potential for highly sensitive diagnosis and evaluation of pathologic hallmarks of acute inflammatory arthritis.
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Affiliation(s)
- David L Chamberland
- University of Michigan School of Medicine, Division of Rheumatology, Department of Internal Medicine, Ann Arbor, Michigan 48109, USA
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974
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In vivo tumor targeting and spectroscopic detection with surface-enhanced Raman nanoparticle tags. Nat Biotechnol 2007; 26:83-90. [DOI: 10.1038/nbt1377] [Citation(s) in RCA: 1904] [Impact Index Per Article: 112.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 12/03/2007] [Indexed: 11/08/2022]
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975
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Tseng SH, Yang C. 2-D PSTD Simulation of optical phase conjugation for turbidity suppression. OPTICS EXPRESS 2007; 15:16005-16016. [PMID: 19550887 DOI: 10.1364/oe.15.016005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Turbidity Suppression via Optical Phase Conjugation (TS-OPC) is an optical phenomenon that uses the back propagation nature of optical phase conjugate light field to undo the effect of tissue scattering. We use the computationally efficient and accurate pseudospectral time-domain (PSTD) simulation method to study this phenomenon; a key adaptation is the volumetric inversion of the optical wavefront E-field as a means for simulating a phase conjugate mirror. We simulate a number of scenarios and demonstrate that TS-OPC deteriorates with increased scattering in the medium, or increased mismatch between the random medium and the phase conjugate wave during reconstruction.
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976
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Wang X, Chamberland DL, Xi G. Noninvasive reflection mode photoacoustic imaging through infant skull toward imaging of neonatal brains. J Neurosci Methods 2007; 168:412-21. [PMID: 18155298 DOI: 10.1016/j.jneumeth.2007.11.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 11/05/2007] [Accepted: 11/06/2007] [Indexed: 11/28/2022]
Abstract
The feasibility of functional imaging of neonatal brains was studied in a noninvasive transcranial manner by using reflection mode photoacoustic technique for the first time. Experiments were conducted to examine the quality of photoacoustic signals and consequent images across a newborn infant skull. With the designed system, photoacoustic imaging of blood vessels through the infant skull has been achieved with an axial resolution up to 50mum and a lateral resolution up to 420mum. Experimental results also indicate that photoacoustic imaging of neonatal brain with a depth of 21mm or more beneath the skull is feasible when working with near-infrared light. Moreover, the performance of this technique for measuring and monitoring the changes in blood oxygenation level through the newborn infant skull has also been explored. This study suggests that reflection mode photoacoustic imaging holds promise to become a novel and powerful tool for noninvasive diagnosis, monitoring and prognosis of disorders in neonatal brains.
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Affiliation(s)
- Xueding Wang
- Department of Radiology, University of Michigan School of Medicine, 200 Zina Pitcher Pl, 3485 Kresge III, Ann Arbor, MI, USA.
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977
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Wang RK. Three-dimensional optical micro-angiography maps directional blood perfusion deep within microcirculation tissue beds in vivo. Phys Med Biol 2007; 52:N531-7. [PMID: 18029974 DOI: 10.1088/0031-9155/52/23/n01] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Optical micro-angiography (OMAG) is a recently developed method of imaging localized blood perfusion at capillary level resolution within microcirculatory beds. This paper reports that the OMAG is capable of directional blood perfusion mapping in vivo. This is achieved simply by translating the mirror located in the reference arm back and forth while 3D imaging is performed. The mirror which moves toward the incident beam gives the blood perfusion that flows away from the beam direction and vice versa. The approach is experimentally demonstrated by imaging of a flow phantom and then cerebro-vascular perfusion of a live mouse with cranium intact.
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Affiliation(s)
- Ruikang K Wang
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR 97237, USA.
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978
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Fang H, Maslov K, Wang LV. Photoacoustic Doppler effect from flowing small light-absorbing particles. PHYSICAL REVIEW LETTERS 2007; 99:184501. [PMID: 17995411 DOI: 10.1103/physrevlett.99.184501] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Indexed: 05/18/2023]
Abstract
From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.
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Affiliation(s)
- Hui Fang
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, Missouri 63130, USA
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979
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Abstract
Until recently most studies of metastasis only measured the end point of the process--macroscopic metastases. Although these studies have provided much useful information, the details of the metastatic process remain somewhat mysterious owing to difficulties in studying cell behaviour with high spatial and temporal resolution in vivo. The use of luminescent and fluorescent proteins and developments in optical imaging technology have enabled the direct observation of cancer cells spreading from their site of origin and arriving at secondary sites. This Review will describe recent advances in our understanding of the different steps of metastasis gained from cellular resolution imaging, and how these techniques can be used in preclinical drug evaluation.
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Affiliation(s)
- Erik Sahai
- Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK.
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980
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Abstract
Tissue engineering is a rapidly growing field that aims to develop biological substitutes that restore, maintain or improve tissue function. The focus of research to date has been the underlying biology required for tissue-engineered therapies. However, as tissue-engineered products reach the marketplace, there is a pressing need for an improved understanding of the engineering and economic issues associated with them. This is motivated by the lack of commercial viability of many of the initial therapies that have been produced. It has been suggested in the literature that this is partly due to poor process and system design in tissue production, as well as a lack of process monitoring and control. This review argues that principles of design, measurement and process monitoring from the physical sciences are needed to move tissue engineering forward, and that much of the technology needed to realize this is already available.
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Affiliation(s)
- Melissa L Mather
- Applied Optics Group, School of Electrical and Electronic Engineering, University of Nottingham, Nottingham, UK
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981
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Wang RK, Hurst S. Mapping of cerebro-vascular blood perfusion in mice with skin and skull intact by Optical Micro-AngioGraphy at 1.3 mum wavelength. OPTICS EXPRESS 2007; 15:11402-12. [PMID: 19547498 DOI: 10.1364/oe.15.011402] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical micro-angiography (OMAG) was developed to achieve volumetric imaging of the microstructures and dynamic cerebrovascular blood perfusion in mice with capillary level resolution and high signal-to-background ratio. In this paper, we present a high-speed and high-sensitivity OMAG imaging system by using an InGaAs line scan camera and broadband light source at 1.3 mum wavelength for enhanced imaging depth in tissue. We show that high quality imaging of cerebrovascular blood perfusion down to capillary level resolution with the intact skin and cranium are obtained in vivo with OMAG, without the interference from the blood perfusion in the overlaying skin. The results demonstrate the potential of 1.3 mum OMAG for high-speed and high-sensitivity imaging of blood perfusion in human and small animal studies.
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982
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Kothapalli SR, Sakadzić S, Kim C, Wang LV. Imaging optically scattering objects with ultrasound-modulated optical tomography. OPTICS LETTERS 2007; 32:2351-3. [PMID: 17700782 DOI: 10.1364/ol.32.002351] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We show the feasibility of imaging objects having different optical scattering coefficients relative to the surrounding scattering medium using ultrasound-modulated optical tomography (UOT). While the spatial resolution depends on ultrasound parameters, the image contrast depends on the difference in scattering coefficient between the object and the surrounding medium. Experimental measurements obtained with a CCD-based speckle contrast detection scheme are in agreement with Monte Carlo simulations and analytical calculations. This study complements previous UOT experiments that demonstrated optical absorption contrast.
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Affiliation(s)
- Sri-Rajasekhar Kothapalli
- Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130-4899, USA
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983
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Kim C, Wang LV. Multi-optical-wavelength ultrasound-modulated optical tomography: a phantom study. OPTICS LETTERS 2007; 32:2285-7. [PMID: 17700760 DOI: 10.1364/ol.32.002285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We used multiple optical wavelengths to study ultrasound-modulated optical tomography (UOT) in tissue phantoms. By using intense acoustic bursts and a CCD camera-based speckle contrast detection technique, we observed variations of the ultrasound-modulated signal at various optical absorptions. The experimental variations were found to be highly correlated with predictions from Monte Carlo simulations. By irradiating the sample at two optical wavelengths, we quantitatively estimated the total concentration and the concentration ratio of double dyes in objects embedded in tissue phantoms. The results suggest that UOT can potentially provide noninvasive functional imaging of the total concentration and oxygen saturation of hemoglobin in biological tissue.
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Affiliation(s)
- Chulhong Kim
- Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
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984
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Zhang HF, Maslov K, Wang LV. In vivo imaging of subcutaneous structures using functional photoacoustic microscopy. Nat Protoc 2007; 2:797-804. [PMID: 17446879 DOI: 10.1038/nprot.2007.108] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Functional photoacoustic microscopy (fPAM) is a hybrid technology that permits noninvasive imaging of the optical absorption contrast in subcutaneous biological tissues. fPAM uses a focused ultrasonic transducer to detect high-frequency photoacoustic (PA) signals. Volumetric images of biological tissues can be formed by two-dimensional raster scanning, and functional parameters can be further extracted from spectral measurements. fPAM is safe and applicable to animals as well as humans. This protocol provides guidelines for parameter selection, system alignment, imaging operation, laser safety and data processing for in vivo fPAM. It currently takes approximately 100 min to carry out this protocol, including approximately 50 min for data acquisition using a 10-Hz pulse-repetition-rate laser system. The data acquisition time, however, can be significantly reduced by using a laser system with a higher pulse repetition rate.
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Affiliation(s)
- Hao F Zhang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
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985
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Cox BT, Kara S, Arridge SR, Beard PC. k-space propagation models for acoustically heterogeneous media: application to biomedical photoacoustics. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2007; 121:3453-64. [PMID: 17552697 DOI: 10.1121/1.2717409] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Biomedical applications of photoacoustics, in particular photoacoustic tomography, require efficient models of photoacoustic propagation that can incorporate realistic properties of soft tissue, such as acoustic inhomogeneities both for purposes of simulation and for use in model-based image reconstruction methods. k-space methods are well suited to modeling high-frequency acoustics applications as they require fewer mesh points per wavelength than conventional finite element and finite difference models, and larger time steps can be taken without a loss of stability or accuracy. They are also straightforward to encode numerically, making them appealing as a general tool. The rationale behind k-space methods and the k-space approach to the numerical modeling of photoacoustic waves in fluids are covered in this paper. Three existing k-space models are applied to photoacoustics and demonstrated with examples: an exact model for homogeneous media, a second-order model that can take into account heterogeneous media, and a first-order model that can incorporate absorbing boundary conditions.
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Affiliation(s)
- B T Cox
- Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, United Kingdom.
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986
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987
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Sivaramakrishnan M, Maslov K, Zhang HF, Stoica G, Wang LV. Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels. Phys Med Biol 2007; 52:1349-61. [PMID: 17301459 DOI: 10.1088/0031-9155/52/5/010] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO2), with a spatial resolution of about 50 microm from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO2 inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO2 quantification in vivo.
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Affiliation(s)
- Mathangi Sivaramakrishnan
- Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A&M University 3120 TAMU, College Station,TX 77843-3120, USA
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988
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Zemp RJ, Bitton R, Li ML, Shung KK, Stoica G, Wang LV. Photoacoustic imaging of the microvasculature with a high-frequency ultrasound array transducer. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:010501. [PMID: 17343475 DOI: 10.1117/1.2709850] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Visualization of microvascular networks could provide new information about function and disease. We demonstrate the capabilities of a 30-MHz ultrasound array system for photoacoustic microscopy of small (< or = 300 microm) vessels in a rat. 3D images obtained by translating the array in the elevation direction are compared with photographs of excised skin. The system is shown to have 100-microm lateral resolution, 25-microm axial resolution, and 3-mm imaging depth. To our knowledge this is the first report on photoacoustic microscopy of the microvasculature with a high-frequency array transducer. It is anticipated that the system can be used for studying and diagnosing a number of diseases including cancer, atherosclerosis, dermatological disorders, and peripheral microvascular complications in diabetes.
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Affiliation(s)
- Roger J Zemp
- Washington University, Optical Imaging Laboratory, Department of Biomedical Engineering, Saint Louis, Missouri 63130, USA
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989
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Dabrowska M, Hendrikx PJ, Skierski J, Malinowska M, Bertino JR, Rode W. EGFP fluorescence as an indicator of cancer cells response to methotrexate. Eur J Pharmacol 2006; 555:93-9. [PMID: 17141212 DOI: 10.1016/j.ejphar.2006.10.052] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Revised: 10/11/2006] [Accepted: 10/13/2006] [Indexed: 10/24/2022]
Abstract
Methotrexate action in viable cells was monitored by registering changes in EGFP (Enhanced Green Fluorescent Protein) fluorescence intensity. Treatment with 1 microM methotrexate for 48 h of human colorectal adenocarcinoma C85 cells, stably transfected to express EGFP, caused 5-fold increase in EGFP fluorescence assayed by flow cytometry with no distinct increase in EGFP protein level. This was correlated with morphological changes, including an increase of cell granularity and cell shape flattening, as well as cell cycle G1 phase arrest revealed by DNA content analysis. Methotrexate removal allowed the morphology of the cells in culture to revert in 10 days to normal. The cells that survived methotrexate exposure were propagated as C85r cell subline and displayed kinetics of methotrexate sensitivity parallel to that of the parental C85 line. As the increase in EGFP fluorescence could also be visualized by fluorescence microscopy, this reporter system may be employed to image methotrexate action in cancer cells in living models.
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Affiliation(s)
- Magdalena Dabrowska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland.
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990
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Zhang HF, Maslov K, Li ML, Stoica G, Wang LV. In vivo volumetric imaging of subcutaneous microvasculature by photoacoustic microscopy. OPTICS EXPRESS 2006; 14:9317-23. [PMID: 19529315 DOI: 10.1364/oe.14.009317] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Photoacoustic microscopy was developed to achieve volumetric imaging of the anatomy and functions of the subcutaneous microvasculature in both small animals and humans in vivo with high spatial resolution and high signal-to-background ratio. By following the skin contour in raster scanning, the ultrasonic transducer maintains focusing in the region of interest. Furthermore, off-focus lateral resolution is improved by using a synthetic-aperture focusing technique based on the virtual point detector concept. Structural images are acquired in both rats and humans, whereas functional images representing hemoglobin oxygen saturation are acquired in rats. After multiscale vesselness filtering, arterioles and venules in the image are separated based on the imaged oxygen saturation levels. Detailed structural information, such as vessel depth and spatial orientation, are revealed by volume rendering.
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991
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Zhang HF, Maslov K, Stoica G, Wang LV. Imaging acute thermal burns by photoacoustic microscopy. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:054033. [PMID: 17092182 DOI: 10.1117/1.2355667] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The clinical significance of a burn depends on the percentage of total body involved and the depth of the burn. Hence a noninvasive method that is able to evaluate burn depth would be of great help in clinical evaluation. To this end, photoacoustic microscopy is used to determine the depth of acute thermal burns by imaging the total hemoglobin concentration in the blood that accumulates along the boundaries of injuries as a result of thermal damage to the vasculature. We induce acute thermal burns in vivo on pig skin with cautery. Photoacoustic images of the burns are acquired after skin excision. In a burn treated at 175 degrees C for 20 s, the maximum imaged burn depth is 1.73+/-0.07 mm. In burns treated at 150 degrees C for 5, 10, 20, and 30 s, respectively, the trend of increasing maximum burn depth with longer thermal exposure is demonstrated.
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Affiliation(s)
- Hao F Zhang
- Department of Biomedical Engineering, Optical Imaging Laboratory, Texas A&M University, 3120 TAMU, College Station, Texas 77843-3120, USA
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992
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In Brief. Nat Rev Drug Discov 2006. [DOI: 10.1038/nrd2127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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