1. Articles from Ruikang K. Wang

    1-24 of 278 1 2 3 4 ... 10 11 12 »
    1. Retinal Capillary Nonperfusion on OCT-Angiography and Its Relationship to Kidney Function in Patients with Diabetes

      Retinal Capillary Nonperfusion on OCT-Angiography and Its Relationship to Kidney Function in Patients with Diabetes

      Background: Diabetic retinopathy and kidney disease share underlying mechanisms of microvascular damage and are often comorbid in people with diabetes. We evaluated whether there is a relationship between retinal capillary perfusion as measured by swept-source optical coherence tomography angiography and estimated glomerular filtration rate (eGFR) and albuminuria in patients with diabetes and chronic kidney disease (CKD). Method: A cross-sectional pilot study was conducted at the University of Washington among a subset of participants with diabetes and CKD participating in a larger cohort study. Participants were excluded if they were known to have kidney disease from conditions other than diabetes. Ten ...

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    2. Optical coherence tomography angiography measures blood pulsatile waveforms at variable tissue depths

      Optical coherence tomography angiography measures blood pulsatile waveforms at variable tissue depths

      Background: Photoplethysmography (PPG) is routinely used to detect the blood pulse signal from skin tissue beds in clinics. However, the origin of the PPG signal remains controversial. The purpose of this study is to explore optical coherence tomography angiography (OCTA) to indicate pulsatile waveforms in the papillary plexus and dermal plexus separately under different hand elevations. Method: Optical microangiography (OMAG) algorithm was used to obtain a 3D OCTA signals, from which the depth-resolved pulsatile blood flow signals were extracted from different skin vascular plexus. The systolic amplitude, crest time, and delta T were measured from the OCTA pulsatile signals when ...

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    3. Optical coherence tomography angiography distortion correction in widefield montage images

      Optical coherence tomography angiography distortion correction in widefield montage images

      Background: Optical coherence tomography (OCT) imaging is inherently susceptible to distortion artifacts due to the natural curvature of the eye. This study proposes a novel model for widefield OCT angiography (OCTA) distortion correction and analyzes the effects of this correction on quantification metrics. Methods: Widefield OCTA images were obtained on normal subjects at five fixation spatial positions. Radial and field distortion correction were applied and images stitched together to form a corrected widefield montage image. Vessel area density (VAD), vessel complexity index (VCI), and flow impairment area were quantified on the original and corrected montage images. Results: This model allows ...

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    4. Choroidal Thickness by Handheld Swept-Source Optical Coherence Tomography in Term Newborns

      Choroidal Thickness by Handheld Swept-Source Optical Coherence Tomography in Term Newborns

      Purpose : To describe normative values for choroidal thickness in newborns and characterize their relationship to vitreoretinal features. Methods : Term newborns underwent awake, handheld swept-source optical coherence tomography (SS-OCT) in this prospective cohort study. An automated segmentation algorithm followed by manual adjustments measured choroidal thickness at the fovea and five perifoveal locations. Two masked, trained graders, with a third mediating disagreements, analyzed scans for vitreoretinal findings. OCT vitreoretinal findings, including dome-shaped macula, subretinal fluid, punctate hyperreflective vitreous opacities, persistent inner retinal layers, foveal ellipsoid zone, tractional and non-tractional vitreous bands, epiretinal membrane, cystoid macular edema, vessel elevation, scalloped retinal layers, hyporeflective ...

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    5. Robust three-dimensional registration on optical coherence tomography angiography for speckle reduction and visualization

      Robust three-dimensional registration on optical coherence tomography angiography for speckle reduction and visualization

      Background: In the clinical applications of optical coherence tomography angiography (OCTA), the repeated scanning and averaging method can provide better contrast with reduced speckle noises in the final results, which are useful for visualizing and quantifying vascular components with high accuracy, reproducibility, and reliability. However, the inevitable patient motion presents a challenge to this method. The objective of this study is to meet this challenge by introducing a 3D registration method to register optical coherence tomography (OCT)/OCTA scans for precise volume averaging of multiple scans to improve the signal-to-noise ratio (SNR) and increase quantification accuracy. Methods: The proposed method ...

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    6. Differences in cerebral blood vasculature and flow in awake and anesthetized mouse cortex revealed by quantitative optical coherence tomography angiography

      Differences in cerebral blood vasculature and flow in awake and anesthetized mouse cortex revealed by quantitative optical coherence tomography angiography

      Background Most of the in vivo neurovascular imaging studies are performed in anesthetized animals. However, anesthesia significantly affects cerebral hemodynamics. New method We applied optical coherence tomography (OCT) methods such as optical microangiography (OMAG) and Doppler optical microangiography (DOMAG) to quantitatively evaluate the effect of anesthesia in cerebral vasculature and blood flow in mouse brain. Results The OMAG results indicated the increase of large vessel diameter and capillary density induced by ketamine-xylazine and isoflurane, meaning that both anesthetics caused vasodilation. In addition, the preliminary results from DOMAG showed that isoflurane increased the baseline cerebral blood flow. Comparison with existing methods ...

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    7. Imaging human skin autograft integration with optical coherence tomography

      Imaging human skin autograft integration with optical coherence tomography

      Background: Skin autografting is a common clinical procedure for reconstructive surgery. Despite its widespread use, very few studies have been conducted to non-invasively evaluate and monitor the vascular and structural features of skin grafts. This study, therefore, aims to demonstrate the potential of optical coherence tomography (OCT) alongside OCT-based angiography (OCTA) to non-invasively image and monitor human skin graft health and integration over time. Methods: An in-house-built clinical prototype OCT system was used to acquire OCT/OCTA images from patients who underwent split-thickness skin graft surgery following severe burn damage to the skin. The OCT imaging was carried out at ...

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    8. Swept source OCTA reveals a link between choriocapillaris blood flow and vision loss in a case of tubercular serpiginous-like choroiditis

      Swept source OCTA reveals a link between choriocapillaris blood flow and vision loss in a case of tubercular serpiginous-like choroiditis

      Optical coherence tomography angiography (OCTA) is a non-invasive technique that is useful in the diagnosis and management of patients with posterior uveitis. Here we report the use of swept source OCTA (SS-OCTA) in a patient with tuberculosis (TB) associated serpiginous like choroiditis (TB-SLC) that made a full visual recovery following treatment with ATT, local and systemic corticosteroids, and systemic immune modulation. By comparing en face images of choriocapillaris (CC) blood flow before and after treatment, we conclude that the patient's visual recovery was associated with resolution of extensive CC flow deficits. This case highlights the utility of SS-OCTA in ...

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    9. Deliberations of an International Panel of Experts on OCTA Nomenclature of nAMD

      Deliberations of an International Panel of Experts on OCTA Nomenclature of nAMD

      A panel of imaging experts was assembled to review neovascular age-related macular degeneration optical coherence tomography angiography descriptors published to date, and test agreement on use of these terms, which was found to be low. Optical coherence tomography angiography (OCTA) has been used to identify and characterize macular neovascularization (MNV) secondary to age-related macular degeneration (AMD). 1-4 Many studies have explored OCTA morphological features of MNV that might serve as biomarkers to assess disease activity and response to treatment. 1-6 The proliferation of studies however has resulted in an OCTA terminology that has been variable and inconsistent. To address inconsistency ...

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    10. Correlations Between Choriocapillaris and Choroidal Measurements and the Growth of Geographic Atrophy using Swept Source OCT Imaging

      Correlations Between Choriocapillaris and Choroidal Measurements and the Growth of Geographic Atrophy using Swept Source OCT Imaging

      Purpose The correlations between enlargement rates (ERs) of geographic atrophy (GA) and choriocapillaris (CC) flow deficits (FDs), mean choroidal thickness (MCT), and choroidal vascularity index (CVI) were investigated using swept source optical coherence tomography (SS-OCT) in age-related macular degeneration (AMD). Design Retrospective review of prospective, observational case series. Methods Eyes with GA from AMD were imaged with SS-OCT (PLEX® Elite 9000; Carl Zeiss Meditec, Inc, Dublin, CA) using 6x6 mm scan pattern. GA lesions were identified and measured using custom en face structural images and annual square root ERs of GA were calculated. At baseline, CC FDs from different regions ...

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    11. Reduced Pulsatile Trabecular Meshwork Motion in Eyes With Primary Open Angle Glaucoma Using Phase-Sensitive Optical Coherence Tomography

      Reduced Pulsatile Trabecular Meshwork Motion in Eyes With Primary Open Angle Glaucoma Using Phase-Sensitive Optical Coherence Tomography

      Purpose: The purpose of this study was to investigate the difference in pulsatile trabecular meshwork (TM) motion between normal and eyes with POAG using phase-sensitive optical coherence tomography (PhS-OCT). Methods: In this cross-sectional study, eight healthy subjects (16 eyes) and nine patients with POAG (18 eyes) were enrolled. A laboratory-based prototype PhS-OCT system was used to measure pulsatile TM motion. PhS-OCT images were analyzed to obtain parameters of pulsatile TM motion (i.e. maximum velocity [MV] and cumulative displacement [CDisp]). Outflow facility and ocular pulse amplitude were measured using pneumotonography. Detection sensitivity was compared among various parameters by calculating the ...

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    12. Quantitative Handheld Swept-Source Optical Coherence Tomography Angiography in Awake Preterm and Full-Term Infants

      Quantitative Handheld Swept-Source Optical Coherence Tomography Angiography in Awake Preterm and Full-Term Infants

      Purpose : To compare retinal vascular parameters acquired by handheld swept-source optical coherence tomography angiography (SS-OCTA) between nonsedated preterm and full-term infants. Methods : Preterm and full-term infants at the University of Washington Medical Center were enrolled. Retinal angiograms (nominal size ∼7 × 7 mm 2 ) were obtained at each routine retinopathy of prematurity (ROP) screening session for preterms and once during the first 72 hours of life for full-terms. Macular vessel area density and nonperfusion area were evaluated on the binarized vasculature map in both small (1.5 × 1.5 mm) and large (3 × 3 mm) quadrants. Average vessel diameter and tortuosity ...

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    13. Optical Coherence Tomography for the Investigation of Skin Adaptation in Lower-Limb Prosthesis Users

      Optical Coherence Tomography for the Investigation of Skin Adaptation in Lower-Limb Prosthesis Users

      Introduction Mechanically induced skin breakdown is a significant problem for many lower-limb prosthesis users. It is known that skin can adapt to the mechanical stresses of prosthesis use thereby reducing the risk of breakdown, yet little is understood about the biology behind skin adaptation . This is a proof-of-concept study for the use of novel, noninvasive optical coherence tomography (OCT) imaging techniques to investigate skin adaptation . Methods Two OCT imaging-based tests were used to evaluate features of the skin that may be involved in adaptation to limb-socket interface stresses. The tests were used to assess the function and structure of the ...

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    14. OCT-Based Angiography and Surface Topography in Burn-Damaged Skin

      OCT-Based Angiography and Surface Topography in Burn-Damaged Skin

      Background and objectives: There is a clinical need for an accurate, non-invasive imaging tool that can provide the objective assessment of burn wounds. The aims of this study are to demonstrate the potential of optical coherence tomography (OCT) in evaluating burn wound healing, as well as exploring the physiological basis of human wound healing. Study design/materials and methods: This was a retrospective study. Seven patients with severe burn wounds who were admitted to Harborview Medical Center were imaged using an in-house-built, clinical-prototype OCT system. OCT imaging was carried out at multiple scan sites on the burned skin across two ...

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    15. Quantitative assessment of choriocapillaris flow deficits in diabetic retinopathy: A swept-source optical coherence tomography angiography study

      Quantitative assessment of choriocapillaris flow deficits in diabetic retinopathy: A swept-source optical coherence tomography angiography study

      Purpose To quantitatively assess choriocapillaris (CC) flow deficits in eyes with diabetic retinopathy (DR) using swept-source optical coherence tomography angiography (SS-OCTA). Methods Diabetic subjects with different stages of DR and age-matched healthy subjects were recruited and imaged with SS-OCTA. The en face CC blood flow images were generated using previously published and validated algorithms. The percentage of CC flow deficits (FD%) and the mean CC flow deficit size were calculated in a 5-mm-diameter circle centered on the fovea from the 6×6-mm scans. Results Forty-five diabetic subjects and 27 control subjects were included in the study. The CC FD% in ...

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    16. Polarization state tracing method to map local birefringent properties in samples using polarization sensitive optical coherence tomography

      Polarization state tracing method to map local birefringent properties in samples using polarization sensitive optical coherence tomography

      We propose a method that utilizes the trajectory of output polarization states on the Poincaré sphere to derive depth-resolved birefringent information within samples using a fiber-based polarization sensitive optical coherence tomography. The apparent (or intermediate) optic axis and the local phase retardation are first obtained by fitting a plane to the adjacent output polarization states along depths in the Poincare sphere. A sequence of 3D rotation operation determined by the local birefringent property of the upper layers is then applied to the apparent axis to finally determine the local optic axis. This method requires only one input polarization state and ...

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    17. Relative retinal flow velocity detection using optical coherence tomography angiography imaging

      Relative retinal flow velocity detection using optical coherence tomography angiography imaging

      Optical coherence tomography angiography (OCTA) imaging is a valuable tool for the visualization of retinal vasculature at an unprecedented level of details. However, due to relatively long time-interval between repeated scans in the conventional OCTA scanning protocol, the OCTA flow signal suffers from low dynamic range and loss of velocity-intensity correlation. The ability to distinguish fast and slow flow in the retina may provide a powerful tool for the assessment of early-stage retinal diseases such as vein occlusion. Here, we report a method to detect relative flow velocity in human retina using a 67.5 kHz spectral-domain OCTA device. By ...

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    18. Polarization sensitive optical coherence tomography for imaging microvascular information within living tissue without polarization-induced artifacts

      Polarization sensitive optical coherence tomography for imaging microvascular information within living tissue without polarization-induced artifacts

      When imaging birefringent samples using optical coherence tomography angiography (OCTA), the phase retardation may appear opposite to the phase change due to the blood flow in the orthogonal signals, for which a cancellation effect can occur when deriving OCTA signals. This effect can diminish the ability of OCTA to detect vascular information, leading to an erroneous interpretation of the final OCTA images. To mitigate this issue, we demonstrate polarization-sensitive optical coherence tomography (PS-OCT) to image microvascular information within a living sample without polarization induced artifacts. The system is furnished with a swept source OCT (SS-OCT) that incorporates two imaging modes ...

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    19. Handheld swept-source optical coherence tomography guided by smartphone-enabled wide-field autofluorescence photography for imaging facial sebaceous glands

      Handheld swept-source optical coherence tomography guided by smartphone-enabled wide-field autofluorescence photography for imaging facial sebaceous glands

      We report a method to image facial sebaceous glands (SGs) using smartphone-enabled wide-field autofluorescence photography (AFP) and handheld swept-source optical coherence tomography (SS-OCT). Smartphone-enabled AFP provides a 2D wide-field fluorescence image that is used both as a functional mapping of the sebum and a positioning guidance for OCT imaging of the SG. Following the guidance, handheld SS-OCT conducts the volume scan to investigate depth-resolved conditions of the SG in the selected regions of interest. We show the results from smartphone-enabled AFP and handheld SS-OCT to demonstrate the ability of our method to image facial SGs, potentially useful for the assessment ...

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    20. Macular microvascular parameters in the ganglion cell-inner plexiform layer derived by optical coherence tomography angiography: Vascular structure-central visual function analysis

      Macular microvascular parameters in the ganglion cell-inner plexiform layer derived by optical coherence tomography angiography: Vascular structure-central visual function analysis

      Purpose To investigate the relationships between global and sectoral macular vascular microcirculation parameters in the ganglion cell-inner plexiform layer (GCIPL) assessed by optical coherence tomography angiography (OCTA), and global and sectoral visual field (VF) central mean sensitivity (CMS) assessed by standard automated perimetry. Methods Fifty-four eyes with open angle glaucoma were scanned using a swept-source OCTA (Plex Elite 9000, Zeiss, Dublin, CA) and macular vascular microcirculation was measured by calculating the overall flux and vessel area density (VAD) over the entire 6mm x 6mm area, excluding large retinal vessels. Central 10-degree VF CMS was calculated based on 24–2 VF ...

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    21. Optical microangiography reveals temporal and depth-resolved hemodynamic change in mouse barrel cortex during whisker stimulation

      Optical microangiography reveals temporal and depth-resolved hemodynamic change in mouse barrel cortex during whisker stimulation

      Significance: Cerebral blood flow (CBF) regulation at neurovascular coupling (NVC) plays an important role in normal brain functioning to support oxygen delivery to activating neurons. Therefore, studying the mechanisms of CBF adjustment is crucial for the improved understanding of brain activity. Aim: We investigated the temporal profile of hemodynamic signal change in mouse cortex caused by neural activation and its variation over cortical depth. Approach: Following the cranial window surgery, intrinsic optical signal imaging (IOSI) was used to spatially locate the activated region in mouse cortex during whisker stimulation. Optical microangiography (OMAG), the functional extension of optical coherence tomography, was ...

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    22. Semi-automated registration and segmentation for gingival tissue volume measurement on 3D OCT images

      Semi-automated registration and segmentation for gingival tissue volume measurement on 3D OCT images

      The change in gingival tissue volume may be used to indicate changes in gingival inflammation, which may be useful for the clinical assessment of gingival health. Properly quantifying gingival tissue volume requires a robust technique for accurate registration and segmentation of longitudinally captured 3-dimensional (3D) images. In this paper, a semi-automated registration and segmentation method for micrometer resolution measurement of gingival-tissue volume is proposed for 3D optical coherence tomography (OCT) imaging. For quantification, relative changes in gingiva tissue volume are measured based on changes in the gingiva surface height using the tooth surface as a reference. This report conducted repeatability ...

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    23. Automated vessel diameter quantification and vessel tracing for OCT angiography

      Automated vessel diameter quantification and vessel tracing for OCT angiography

      Optical coherence tomography angiography (OCTA) is capable of non‐invasively imaging the vascular networks within circulatory tissue beds in vivo. Following improvements in OCTA image quality, it is now possible to extract vascular parameters from imaging data to potentially facilitate the diagnosis and treatment of human disease. In this paper, we present a method for automated mapping of vessel diameter down to the individual capillary level, through gradient‐guided minimum radial distance (MRD). During validation using well‐characterized microfluidic flow phantoms, this method demonstrated superior consistency and a nearly threefold decrease in error when compared to currently accepted techniques. In ...

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    24. OCT Angiography to Predict Geographic Atrophy Progression using Choriocapillaris Flow Void as a Biomarker

      OCT Angiography to Predict Geographic Atrophy Progression using Choriocapillaris Flow Void as a Biomarker

      Purpose : To investigate the relationship between choriocapillaris (CC) flow void (FV) percentage and geographic atrophy (GA) growth rate, and study how variations in FV percentage surrounding GA predict regional GA growth. Methods : This prospective, longitudinal study enrolled subjects with GA secondary to nonexudative age-related macular degeneration. Optical coherence tomography angiography imaged the CC and FV percentage was evaluated using a validated algorithm. GA growth rate was measured as the difference in the square root of GA area divided by the months between baseline and follow-up imaging. Results : Twelve eyes from 7 subjects with a mean age of 80 ± 5 years ...

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    Use of a scanner to modulate spatial interferograms for in vivo full-range Fourier-domain optical coherence tomography The study of effects of pore architecture in chitosan scaffolds on the fluid flow pattern by Doppler OCT Volumetric in vivo imaging of intracochlear microstructures in mice by high-speed spectral domain optical coherence tomography Phase-sensitive optical coherence tomography imaging of the tissue motion within the organ of Corti at a subnanometer scale: a preliminary study Volumetric In Vivo Imaging of Microvascular Perfusion Within the Intact Cochlea in Mice Using Ultra-High Sensitive Optical Microangiography Volumetric and quantitative imaging of retinal blood flow in rats with optical microangiography Feature Of The Week 01/25/15: Detection and characterisation of biopsy tissue using quantitative optical coherence elastogaphy (OCE) in men with suspected prostate cancer. Portable Optical Coherence Elastography System With Flexible and Phase Stable Common Path Optical Fiber Probe Strategies to Improve Convolutional Neural Network Generalizability and Reference Standards for Glaucoma Detection From OCT Scans Automatic detection of retinopathy with optical coherence tomography images via a semi-supervised deep learning method Reduced Retinal Microvascular Perfusion in Patients With Stroke Detected by Optical Coherence Tomography Angiography Optical coherence tomography angiography findings in diabetic macular edema