The Experts below are selected from a list of 63672 Experts worldwide ranked by ideXlab platform
Lihong V Wang - One of the best experts on this subject based on the ideXlab platform.
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Photoacoustic tomography of water in Biological Tissue
Proceedings of SPIE, 2011Co-Authors: Zhun Xu, Changhui Li, Lihong V WangAbstract: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.
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depth resolved two dimensional stokes vectors of backscattered light and mueller matrices of Biological Tissue measured with optical coherence tomography
Applied Optics, 2000Co-Authors: Shuliang Jiao, Lihong V WangAbstract:Mueller matrices provide a complete characterization of the optical polarization properties of Biological Tissue. A polarization-sensitive optical coherence tomography (OCT) system was built and used to investigate the optical polarization properties of Biological Tissues and other turbid media. The apparent degree of polarization (DOP) of the backscattered light was measured with both liquid and solid scattering samples. The DOP maintains the value of unity within the detectable depth for the solid sample, whereas the DOP decreases with the optical depth for the liquid sample. Two-dimensional depth-resolved images of both the Stokes vectors of the backscattered light and the full Mueller matrices of Biological Tissue were measured with this system. These polarization measurements revealed some Tissue structures that are not perceptible with standard OCT.
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Study of ultrasound-modulated optical tomography in Biological Tissue with parallel detection
Proceedings of the 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Cat. No.00CH37143), 2000Co-Authors: Lihong V WangAbstract:An ultrasonic beam was focused into a Biological Tissue sample to modulate the laser light passing through the ultrasonic beam inside the Tissue. The speckle field formed by the transmitted laser light was detected by a CCD camera with the source-synchronous-illumination lock-in technique. The ultrasound-modulated laser light reflects the local optical and mechanical properties within the ultrasonic beam and can be used for tomographic imaging of the Tissue. Spatial resolution along the ultrasonic axis was achieved by sweeping the ultrasonic frequency. Two-dimensional images of Biological Tissue were successfully obtained with both single frequency modulation and frequency-swept modulation. Three-dimensional images could be acquired as well in principle.
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scanning thermoacoustic tomography in Biological Tissue
Medical Physics, 2000Co-Authors: Geng Ku, Lihong V WangAbstract:Microwave-induced thermoacoustic tomography was explored to image Biological Tissue. Short microwave pulses irradiated Tissue to generate acoustic waves by thermoelastic expansion. The microwave-induced thermoacoustic waves were detected with a focused ultrasonic transducer. Each time-domain signal from the ultrasonic transducer represented a one-dimensional image along the acoustic axis of the ultrasonic transducer similar to an ultrasonic A-scan. Scanning the system perpendicularly to the acoustic axis of the ultrasonic transducer would generate multi-dimensional images. Two-dimensional tomographic images of Biological Tissue were obtained with 3-GHz microwaves. The axial and lateral resolutions were characterized. The time-domain piezo-electric signal from the ultrasonic transducer in response to the thermoacoustic signal was simulated theoretically, and the theoretical result agreed with the experimental result very well.
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Theoretical and experimental studies of ultrasound-modulated optical tomography in Biological Tissue.
Applied Optics, 2000Co-Authors: Lihong V WangAbstract:Ultrasound-modulated optical tomography in Biological Tissue was studied both theoretically and experimentally. An ultrasonic beam was focused into Biological Tissue samples to modulate the laser light passing through the ultrasonic beam inside the Tissue. The ultrasound-modulated laser light reflects the local optical and mechanical properties in the ultrasonic beam and permits tomographic imaging of Biological Tissues by scanning. Parallel detection of the speckle field formed by the transmitted laser light was implemented with the source-synchronous-illumination lock-in technique to improve the signal-to-noise ratio. Two-dimensional images of Biological Tissues were successfully obtained experimentally with a laser beam at either normal or oblique incidence, which showed that ultrasound-modulated optical tomography depends on diffuse light rather than on ballistic light. Monte Carlo simulations showed that the modulation depth decreased much more slowly than the diffuse transmittance, which indicated the possibility that even thicker Biological Tissues can be imaged with this technique.
Geng Ku - One of the best experts on this subject based on the ideXlab platform.
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scanning thermoacoustic tomography in Biological Tissue
Medical Physics, 2000Co-Authors: Geng Ku, Lihong V WangAbstract:Microwave-induced thermoacoustic tomography was explored to image Biological Tissue. Short microwave pulses irradiated Tissue to generate acoustic waves by thermoelastic expansion. The microwave-induced thermoacoustic waves were detected with a focused ultrasonic transducer. Each time-domain signal from the ultrasonic transducer represented a one-dimensional image along the acoustic axis of the ultrasonic transducer similar to an ultrasonic A-scan. Scanning the system perpendicularly to the acoustic axis of the ultrasonic transducer would generate multi-dimensional images. Two-dimensional tomographic images of Biological Tissue were obtained with 3-GHz microwaves. The axial and lateral resolutions were characterized. The time-domain piezo-electric signal from the ultrasonic transducer in response to the thermoacoustic signal was simulated theoretically, and the theoretical result agreed with the experimental result very well.
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Scanning thermoacoustic tomography in Biological Tissue
Medical Physics, 2000Co-Authors: Geng Ku, Lei WangAbstract:Microwave-induced thermoacoustic tomography was explored to image Biological Tissue. Short microwave pulses irradiated Tissue to generate acoustic waves by thermoelastic expansion. The microwave-induced thermoacoustic waves were detected with a focused ultrasonic transducer. Each time-domain signal from the ultrasonic transducer represented a one-dimensional image along the acoustic axis of the ultrasonic transducer similar to an ultrasonic A-scan. Scanning the system perpendicularly to the acoustic axis of the ultrasonic transducer would generate multi-dimensional images. Two-dimensional tomographic images of Biological Tissue were obtained with 3-GHz microwaves. The axial and lateral resolutions were characterized. The time-domain piezo-electric signal from the ultrasonic transducer in response to the thermoacoustic signal was simulated theoretically, and the theoretical result agreed with the experimental result very well. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)03105-9].
Lei Wang - One of the best experts on this subject based on the ideXlab platform.
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Scanning thermoacoustic tomography in Biological Tissue
Medical Physics, 2000Co-Authors: Geng Ku, Lei WangAbstract:Microwave-induced thermoacoustic tomography was explored to image Biological Tissue. Short microwave pulses irradiated Tissue to generate acoustic waves by thermoelastic expansion. The microwave-induced thermoacoustic waves were detected with a focused ultrasonic transducer. Each time-domain signal from the ultrasonic transducer represented a one-dimensional image along the acoustic axis of the ultrasonic transducer similar to an ultrasonic A-scan. Scanning the system perpendicularly to the acoustic axis of the ultrasonic transducer would generate multi-dimensional images. Two-dimensional tomographic images of Biological Tissue were obtained with 3-GHz microwaves. The axial and lateral resolutions were characterized. The time-domain piezo-electric signal from the ultrasonic transducer in response to the thermoacoustic signal was simulated theoretically, and the theoretical result agreed with the experimental result very well. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)03105-9].
W. Rutten - One of the best experts on this subject based on the ideXlab platform.
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Determination of the optical impulse response function of Biological Tissue and technical constraints
Proceedings of 18th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1996Co-Authors: A. Zimolong, E. Gaelings, W. RuttenAbstract:Optical tomography of Biological Tissue is struggling with blurred pictures due to high scattering of photons. We describe a procedure to overcome this problem by employing measurement techniques in the frequency domain in order to determine the optical impulse response function. After introducing problems of optical tomography and realized solutions, an arrangement is described which utilizes frequency domain measurements based on direct modulation of a laser diode and detection by a photodiode. The principle function is demonstrated by measuring optical properties of a test system.
Moungi G Bawendi - One of the best experts on this subject based on the ideXlab platform.
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absorption by water increases fluorescence image contrast of Biological Tissue in the shortwave infrared
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Jessica A Carr, Marianne Aellen, Daniel Franke, Peter T C So, Oliver T Bruns, Moungi G BawendiAbstract:Recent technology developments have expanded the wavelength window for Biological fluorescence imaging into the shortwave infrared. We show here a mechanistic understanding of how drastic changes in fluorescence imaging contrast can arise from slight changes of imaging wavelength in the shortwave infrared. We demonstrate, in 3D Tissue phantoms and in vivo in mice, that light absorption by water within Biological Tissue increases image contrast due to attenuation of background and highly scattered light. Wavelengths of strong Tissue absorption have conventionally been avoided in fluorescence imaging to maximize photon penetration depth and photon collection, yet we demonstrate that imaging at the peak absorbance of water (near 1,450 nm) results in the highest image contrast in the shortwave infrared. Furthermore, we show, through microscopy of highly labeled ex vivo Biological Tissue, that the contrast improvement from water absorption enables resolution of deeper structures, resulting in a higher imaging penetration depth. We then illustrate these findings in a theoretical model. Our results suggest that the wavelength-dependent absorptivity of water is the dominant optical property contributing to image contrast, and is therefore crucial for determining the optimal imaging window in the infrared.
