1. Articles from Qiang Wang

    1-15 of 15
    1. Jones matrix‐based speckle‐decorrelation angiography using polarization‐sensitive optical coherence tomography

      Jones matrix‐based speckle‐decorrelation angiography using polarization‐sensitive optical coherence tomography

      We show that polarization‐sensitive optical coherence tomography angiography (PS‐OCTA) based on full Jones matrix assessment of speckle decorrelation offers improved contrast and depth of vessel imaging over conventional OCTA. We determine how best to combine the individual Jones matrix elements and compare the resulting image quality to that of a conventional OCT scanner by co‐locating and imaging the same skin locations with closely matched scanning setups. Vessel projection images from finger and forearm skin demonstrate the benefits of Jones matrix‐based PS‐OCTA. Our study provides a promising starting point and a useful reference for future pre ...

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    2. Short-time series optical coherence tomography angiography and its application to cutaneous microvasculature

      Short-time series optical coherence tomography angiography and its application to cutaneous microvasculature

      We present a new optical coherence tomography (OCT) angiography method for imaging tissue microvasculature in vivo based on the characteristic frequency-domain flow signature in a short time series of a single voxel. The angiography signal is generated by Fourier transforming the OCT signal time series from a given voxel in multiple acquisitions and computing the average magnitude of non-zero (high-pass) frequency components. Larger temporal variations of the OCT signal caused by blood flow result in higher values of the average magnitude in the frequency domain compared to those from static tissue. Weighting of the signal by the inverse of the ...

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    3. Label‐free volumetric imaging of conjunctival collecting lymphatics ex vivo by optical coherence tomography lymphangiography

      Label‐free volumetric imaging of conjunctival collecting lymphatics ex vivo by optical coherence tomography lymphangiography

      We employ optical coherence tomography (OCT) and optical coherence microscopy (OCM) to study conjunctival lymphatics in porcine eyes ex vivo . This study is a precursor to the development of in vivo imaging of the collecting lymphatics for potentially guiding and monitoring glaucoma filtration surgery. OCT scans at 1300 nm and higher‐resolution OCM scans at 785 nm reveal the lymphatic vessels via their optical transparency. Equivalent signal characteristics are also observed from blood vessels largely free of blood (and devoid of flow) in the ex vivo conjunctiva. In our lymphangiography, vessel networks were segmented by compensating the depth attenuation in ...

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    4. Adaptive optics optical coherence tomography with dynamic retinal tracking

      Adaptive optics optical coherence tomography with dynamic retinal tracking

      Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction ...

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    5. Henle fiber layer phase retardation measured with polarization-sensitive optical coherence tomography

      Henle fiber layer phase retardation measured with polarization-sensitive optical coherence tomography

      Abstract: We developed a method based on polarization-sensitive optical coherence tomography (PS-OCT) to quantify the double pass phase retardation (DPPR) induced by Henle fiber layer in three subjects. Measurements of the retina were performed at a mean wavelength of 840 nm using two polarization states that were perpendicular in a Poincaré sphere representation and phase retardation contributions from tissue layers above and below the Henle fiber layer were excluded using appropriately placed reference and measurement points. These points were semi-automatically segmented from intensity data. Using a new algorithm to determine DPPR, the Henle fiber layer in three healthy subjects aged ...

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    6. 3D image noise reduction and contrast enhancement in optical coherence tomography

      3D image noise reduction and contrast enhancement in optical coherence tomography

      A novel noise reduction algorithm is proposed for reducing the noise and enhancing the contrast in 3D Optical Coherence Tomography (OCT) images. First, the OCT image is divided into two subregions based on the local noise property: the background area in which the additive noise is dominant and the foreground area in which the multiplicative noise is dominant. In the background, the noise is eliminated by the 2D linear filtering combined with the frame averaging. In the foreground, the noise is eliminated by the 3D linear filtering-an extension of the 2D linear filtering. Therefore, the denoised image is reconstructed according ...

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    7. Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors

      Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors

      Optical coherence tomography with adaptive optics (AO-OCT) is a noninvasive method for imaging the living retina at the microscopic level. We used AO-OCT technology to follow changes in cone photoreceptor outer segment (OS) length and reflectance. To substantially increase sensitivity of the length measurements, a novel phase retrieval technique was demonstrated, capable of detecting changes on a nanometer scale. We acquired volume videos of 0.65°x0.65° retinal patches at 1.5° temporal to the fovea over 75 and 105 minutes in two subjects. Volumes were dewarped and registered, after which the cone intensity, OS length, and referenced phase ...

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    8. Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics

      Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics
      The cone photoreceptor’s outer segment (OS) experiences changes in optical path length, both in response to visible stimuli and as a matter of its daily course of renewal and shedding. These changes are of interest, to quantify function in healthy cells and assess dysfunction in diseased ones. While optical coherence tomography (OCT), combined with adaptive optics (AO), has permitted unprecedented three-dimensional resolution in the living retina, it has not generally been able to measure these OS dynamics, whose scale is smaller than OCT’s axial resolution of a few microns. A possible solution is to take advantage of the ...
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    9. Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics

      Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics
      Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3 × 3 × 3 μm3 resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3° × 3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n = 5; 29–62 years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were ...
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    10. Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics

      Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics
      Cone photoreceptors in the living human eye have recently been imaged with micron-scale resolution in all three spatial dimensions using adaptive optics optical coherence tomography. While these advances have allowed non-invasive study of the three-dimensional structure of living human cones, studies of their function and physiology are still hampered by the difficulties to monitor the same cells over time. The purpose of this study is to demonstrate the feasibility of cone monitoring using ultrahigh-resolution adaptive optics optical coherence tomography. Critical to this is incorporation of a high speed CMOS camera (125 KHz) and a novel feature-based, image registration/dewarping algorithm ...
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    11. 3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics

      3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics

      Optical coherence tomography with adaptive optics (AO-OCT) is a highly sensitive, noninvasive method for 3D imaging of the microscopic retina. The purpose of this study is to advance AO-OCT technology by enabling repeated imaging of cone photoreceptors over extended periods of time (days). This sort of longitudinal imaging permits monitoring of 3D cone dynamics in both normal and diseased eyes, in particular the physiological processes of disc renewal and phagocytosis, which are disrupted by retinal diseases such as age related macular degeneration and retinitis pigmentosa. For this study, the existing AO-OCT system at Indiana underwent several major hardware and software ...

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    12. Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics

      Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics
      Purpose: Ultrahigh-resolution optical coherence tomography (UHR-OCT) with adaptive optics (AO) provides micron-scale 3D resolution that is attractive for imaging the retinal microvasculature. Such imaging may be useful for early detection of pathologic changes as in diabetic retinopathy. Here we investigate this potential for detecting individual capillaries in healthy subjects. Methods: UHR-AO-OCT volumes centered on the fovea were acquired from seven subjects (25-61 years) with three pre-selected with no foveal avascular zone (FAZ). Images were compared to entoptic diagrams using the capillaries at the rim of the FAZ. Methods of comparison were: testing for the presence of a FAZ; noting distinct ...
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    13. Three-dimensional optical coherence tomography imaging of retinal sheet implants in live rats

      Three-dimensional optical coherence tomography imaging of retinal sheet implants in live rats
      Purpose To obtain three-dimensional images from retinal transplants in live animals and evaluate the placement and structural quality of the transplants. Methods Donor retinal sheets were isolated from E19 fetuses of transgenic rats expressing human alkaline phosphatase (hPAP), and transplanted to the subretinal space of 19–56 days old S334ter-3 rat recipients with fast retinal degeneration (average age at surgery 32 days). A total of 143 rats were imaged 1 day to 2.8 months after surgery, using a Fourier-domain optical coherence tomography (FDOCT) system, with an axial resolution of 3.5 μm. The CCD A-line integration time was set ...
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    14. Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics

      Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics
      Ultrahigh speed line scan detectors based on CMOS technology have been recently demonstrated in ultrahigh resolution spectral-domain optical coherence tomography (UHR-SD-OCT) for retinal imaging. While successful, fundamental tradeoffs exist been image acquisition time, image sampling density, and sensitivity, all of which impact the extent of motion artifacts, visualization of fine spatial detail, and detection of faint reflections. Here we investigate these tradeoffs for imaging retinal nerve fiber bundles (RNFBs) using UHR-SD-OCT with adaptive optics (AO). Volume scans of 3°x3° and 1.5°x1.5° were acquired at retinal locations of 3° nasal and 6° superior to the fovea on ...
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    15. Thermoelastic optical Doppler tomography of biological tissues

      Thermoelastic optical Doppler tomography of biological tissues
      In this presentation, we demonstrate a novel optical tomography technique, thermoelastic optical Doppler tomography (ODT). Short laser pulses are used to generate thermoelastic waves in biological samples. Optical phase variations in response to wave propagation are detected using ODT. It is shown that areas of different elastic property in the phantom can be clearly resolved.
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    1-15 of 15
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  2. Topics in the News

    1. (15 articles) Qiang Wang
    2. (10 articles) Indiana University
    3. (9 articles) Donald T. Miller
    4. (8 articles) Omer P. Kocaoglu
    5. (7 articles) Ravi S. Jonnal
    6. (5 articles) Weihua Gao
    7. (5 articles) Barry Cense
    8. (3 articles) University of Western Australia
    9. (3 articles) David D. Sampson
    10. (2 articles) Zhongping Chen
    11. (1 articles) University of Sydney
    12. (1 articles) University of Zurich
    13. (1 articles) UCSD
    14. (1 articles) University of Pittsburgh
    15. (1 articles) L V Prasad Eye Institute
    16. (1 articles) Giuseppe Querques
    17. (1 articles) Carl Zeiss Meditec
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    Thermoelastic optical Doppler tomography of biological tissues Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics Three-dimensional optical coherence tomography imaging of retinal sheet implants in live rats Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics 3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors Henle fiber layer phase retardation measured with polarization-sensitive optical coherence tomography Optical coherence tomography features of neovascularization in proliferative diabetic retinopathy: a systematic review Retinal microvascular metrics in untreated essential hypertensives using optical coherence tomography angiography