1. Articles from Ruikang K. Wang

    1-24 of 253 1 2 3 4 ... 9 10 11 »
    1. Validation of a Compensation Strategy used to Detect Choriocapillaris Flow Deficits Under Drusen with Swept Source OCT Angiography

      Validation of a Compensation Strategy used to Detect Choriocapillaris Flow Deficits Under Drusen with Swept Source OCT Angiography

      Purpose A compensation strategy that was developed to measure the choriocapillaris (CC) flow deficits (FDs) under drusen was tested in eyes with large drusen from age-related macular degeneration (AMD) before and after the drusen spontaneously resolved without evidence of disease progression. Design Prospective, observational consecutive case series. Methods Patients with AMD were enrolled in a prospective SS-OCT imaging study (PLEX® Elite 9000, Carl Zeiss Meditec). Consecutive eyes with large drusen were followed, and eyes that underwent spontaneous collapse of drusen without evidence of disease progression were identified retrospectively. The drusen-resolved regions were manually outlined. CC FDs were measured using a ...

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    2. Quantitative Analysis of the Choriocapillaris in Uveitis Using en face Swept Source Optical Coherence Tomography Angiography

      Quantitative Analysis of the Choriocapillaris in Uveitis Using en face Swept Source Optical Coherence Tomography Angiography

      Purpose To perform a quantitative analysis of choriocapillaris (CC) flow deficits (FDs) in patients with uveitis. Design Retrospective cross-sectional study Methods Swept-source optical coherence tomography based angiography (SS-OCTA) macular volume scans (3x3 mm and 6x6 mm) were obtained using the PLEX® Elite 9000: En face CC images were generated and analyzed using an automated flow deficit identification algorithm. Three quantitative metrics were determined for each eye: FD number (FDN), mean FD size (MFDS), and FD density (FDD). Quantitative metrics were compared between uveitis and control eyes. The uveitis cohort was further subdivided by the presence or absence of choroidal involvement ...

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    3. Mean-Subtraction Method for De-shadowing of Tail Artifacts in Cerebral OCTA Images: A Proof of Concept

      Mean-Subtraction Method for De-shadowing of Tail Artifacts in Cerebral OCTA Images: A Proof of Concept

      When imaging brain vasculature with optical coherence tomography angiography (OCTA), volumetric analysis of cortical vascular networks in OCTA datasets is frequently challenging due to the presence of artifacts, which appear as multiple-scattering tails beneath superficial large vessels in OCTA images. These tails shadow underlying small vessels, making the assessment of vascular morphology in the deep cortex difficult. In this work, we introduce an image processing technique based on mean subtraction of the depth profile that can effectively reduce these tails to better reveal small hidden vessels compared to the current tail removal approach. With the improved vascular image quality, we ...

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    4. Optical coherence tomography for the investigation of skin adaptation to mechanical stress

      Optical coherence tomography for the investigation of skin adaptation to mechanical stress

      Background Skin breakdown due to limb‐socket interface stress is a significant problem for lower limb prosthesis users. While it is known that skin can adapt to stress to become more resistant to breakdown, little is understood about skin adaptation and few methods exist to noninvasively investigate it. In this study, we present novel, noninvasive imaging methods using Optical Coherence Tomography (OCT) to assess key features of the cutaneous microvasculature that may be involved in skin adaptation. Materials and Methods Eight able‐bodied participants wore a modified below‐knee prosthetic socket for two weeks to stress the skin of their ...

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    5. Non‐invasive multimodal imaging by integrating optical coherence tomography with autofluorescence imaging for dental applications

      Non‐invasive multimodal imaging by integrating optical coherence tomography with autofluorescence imaging for dental applications

      We report the development of an integrated multi‐functional imaging system capable of providing anatomical (optical coherence tomography, OCT), functional (OCT angiography, OCTA) and molecular imaging (light‐induced autofluorescence, LIAF) for in vivo dental applications. Blue excitation light (405 nm) was used for LIAF imaging, while the OCT was powered by a 1310 nm swept laser source. A red‐green‐blue (RGB) digital camera, with a 450 nm cut‐on broad‐band optical filter, was used for LIAF detection. The exciting light source and camera were integrated directly with the OCT scanning probe. The integrated system used two non‐invasive ...

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    6. Measurement and visualization of stimulus-evoked tissue dynamics in mouse barrel cortex using phase-sensitive optical coherence tomography

      Measurement and visualization of stimulus-evoked tissue dynamics in mouse barrel cortex using phase-sensitive optical coherence tomography

      We describe a method to measure tissue dynamics in mouse barrel cortex during functional activation via phase-sensitive optical coherence tomography (PhS-OCT). The method measures the phase changes in OCT signals, which are induced by the tissue volume change, upon which to localize the activated tissue region. Phase unwrapping, compensation and normalization are applied to increase the dynamic range of the OCT phase detection. To guide the OCT scanning, intrinsic optical signal imaging (IOSI) system equipped with a green light laser source (532 nm) is integrated with the PhS-OCT system to provide a full field time-lapsed images of the reflectance that ...

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    7. Ultra-Widefield Protocol Enhances Automated Classification of Diabetic Retinopathy Severity with Optical Coherence Tomography Angiography

      Ultra-Widefield Protocol Enhances Automated Classification of Diabetic Retinopathy Severity with Optical Coherence Tomography Angiography

      Purpose To assess the diagnostic utility of retinal nonperfusion to classify eyes based on diabetic retinopathy (DR) severity on optical coherence tomography angiography (OCTA). To determine whether wider field of view (FOV) OCTA protocols enhance the diagnostic utility of retinal nonperfusion in the classification of DR severity. Design Retrospective cross-sectional study Subjects Diabetic patients undergoing ultra-widefield OCTA imaging at one academic retina practice Methods Ultra-widefield OCTA images with 100 degree FOV were obtained from 60 eyes. Eyes were grouped as diabetes without retinopathy (DWR), nonproliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR). The ratio of nonperfusion (RNP) was expressed ...

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    8. Electrically tunable lens integrated with optical coherence tomography angiography for cerebral blood flow imaging in deep cortical layers in mice

      Electrically tunable lens integrated with optical coherence tomography angiography for cerebral blood flow imaging in deep cortical layers in mice

      We report the use of an electrically tunable lens (ETL) in a 1.3 μm spectral-domain optical coherence tomography (SD-OCT) system to overcome the depth of focus (DOF) limitation in conventional OCT systems for OCT angiography (OCTA) in a mouse cerebral cortex. The ETL provides fast and dynamic control of the axial focus of the probe beam along the entire range of the mouse cortex, upon which we performed cerebral blood flow imaging of all cortical layers by stitching the OCTA images automatically captured at six focal depths. Capillary vasculature and axial blood flow velocity were revealed in distinctive cortical ...

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    9. Handheld swept-source optical coherence tomography with angiography in awake premature neonates

      Handheld swept-source optical coherence tomography with angiography in awake premature neonates

      Background: Retinopathy of prematurity (ROP) can lead to retinal detachment and severe vision loss and is a common cause of childhood blindness. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality that can be used to detect potential abnormalities in the microvasculature in this population. The objective of this study is to assess the feasibility of a newly developed handheld swept source OCT (SS-OCT) device to successfully acquire structural vitreoretinal and retinal microvascular images in awake premature infants. Methods: OCT and OCTA images were acquired at the time of routine ROP examinations from awake, unsedated preterm infants in the ...

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    10. Correlations between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes using Swept Source OCT Angiography

      Correlations between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes using Swept Source OCT Angiography

      Purpose Choriocapillaris (CC) imaging of normal eyes with swept-source optical coherence tomography SS-OCTA was performed, and the percentage of CC flow deficits (FD%) and the average area of CC flow deficits (FDa) were compared within given macular regions. Design A prospective, cross-sectional study. Methods Subjects with normal eyes ranging in age from their 20s through their 80s were imaged with SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec, Dublin, CA) using both 3x3 mm and 6x6 mm macular scan patterns. The CC images were generated using a previously published and validated algorithm. In both 3x3 mm and 6x6 mm scans, the ...

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    11. Spatial resolution in dynamic optical coherence elastography

      Spatial resolution in dynamic optical coherence elastography

      Dynamic optical coherence elastography (OCE) tracks elastic wave propagation speed within tissue, enabling quantitative three-dimensional imaging of the elastic modulus. We show that propagating mechanical waves are mode converted at interfaces, creating a finite region on the order of an acoustic wavelength where there is not a simple one-to-one correspondence between wave speed and elastic modulus. Depending on the details of a boundary’s geometry and elasticity contrast, highly complex propagating fields produced near the boundary can substantially affect both the spatial resolution and contrast of the elasticity image. We demonstrate boundary effects on Rayleigh waves incident on a vertical ...

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    12. Two-Year Risk of Exudation in Eyes with Nonexudative Age-Related Macular Degeneration and Subclinical Neovascularization Detected with Swept Source Optical Coherence Tomography Angiography

      Two-Year Risk of Exudation in Eyes with Nonexudative Age-Related Macular Degeneration and Subclinical Neovascularization Detected with Swept Source Optical Coherence Tomography Angiography

      Purpose Swept source optical coherence tomography angiography (SS-OCTA) was used to study the prevalence, incidence, and natural history of subclinical macular neovascularization (MNV) in eyes with unilateral nonexudative age-related macular degeneration. Design Prospective cohort study. Methods Patients were imaged using 3- × 3-mm and 6- × 6-mm SS-OCTA scan patterns. MNV was detected using the outer retina to choriocapillaris en face slab. Prevalence and incidence of subclinical MNV, Kaplan–Meier cumulative estimates for the overall risk of exudation, and the association between neovascular lesion size and the risk of exudation were assessed through 2 years. Results From August 2014 through March 2018 ...

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    13. Systems and methods for in vivo visualization of lymphatic vessels with optical coherence tomography

      Systems and methods for in vivo visualization of lymphatic vessels with optical coherence tomography

      The present technology relates generally to systems and methods for in vivo visualization of lymphatic vessels. A system includes an optical coherence tomography (OCT) device and a computing device coupled to the OCT device configured to cause the OCT device to perform an OCT scan, generate image data in response to the OCT scan, and apply an eigendecomposition filter to the image data to produce processed image data. Alternatively or in addition, the computing device can compensate for scattering attenuation along an optical axis of the OCT scan in the image data set to generate compensated image data, enhance contrast ...

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    14. Quantifying choriocapillaris hypoperfusion in patients with choroidal neovascularization using swept-source OCT angiography

      Quantifying choriocapillaris hypoperfusion in patients with choroidal neovascularization using swept-source OCT angiography

      Purpose: To compare choriocapillaris flow voids (FV) in patients with neovascular age-related macular degeneration (AMD) with age-matched normal controls using swept-source optical coherence tomography angiography (SS-OCTA). Patients and methods: Eleven eyes of 11 subjects with neovascular AMD and 11 eyes of 11 age-similar normal subjects were imaged using SS-OCTA with a 6x6mm scanning pattern. Choriocapillaris FV, defined as a percentage of regions determined to have flow deficits divided by the total scanned region, was measured using a one standard deviation thresholding algorithm developed from a database of age-similar normal subjects. Results: Choriocapillaris FV was more extensive in patients with choroidal ...

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    15. Quantification of choriocapillaris with OCTA: a comparison study

      Quantification of choriocapillaris with OCTA: a comparison study

      Purpose To demonstrate the variation in quantitative choriocapillaris (CC) metrics with various binarization approaches using optical coherence tomography angiography (OCTA). Design Retrospective, observational, cross-sectional case series. Methods 3x3 mm and 6x6 mm macular OCTA scans were obtained from normal eyes and from eyes with drusen secondary to AMD. The CC slab was extracted and the CC flow deficits (FDs) were segmented with two previously published algorithms: fuzzy C-means approach (FCM method) and Phansalkar’s local thresholding (Phansalkar method). Four different values for the radius were used in order to investigate the effect on the FD segmentation when using the Phansalkar ...

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    16. Systems and methods for quantitative assessment of microvasculature using optical coherence tomography angiography

      Systems and methods for quantitative assessment of microvasculature using optical coherence tomography angiography

      A five-index quantitative analysis of OCT angiograms is disclosed. One method of analyzing an anatomical region of interest of a subject includes acquiring vascular image data from the region of interest and generating a binary vasculature map from the vascular image data. A vessel skeleton map and vessel perimeter map are generated from the binary vasculature map. Based on the three generated maps, a vessel area density, vessel skeleton density, vessel perimeter index, vessel diameter index, and vessel complexity can be determined, in addition to detection of any flow impairment zones in the region of interest. These metrics can be ...

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    17. Impaired Retinal Vascular Reactivity in Diabetic Retinopathy as Assessed by Optical Coherence Tomography Angiography

      Impaired Retinal Vascular Reactivity in Diabetic Retinopathy as Assessed by Optical Coherence Tomography Angiography

      Purpose : To assess retinal vascular reactivity in healthy controls and subjects with diabetic retinopathy (DR). Methods : A total of 22 healthy control eyes and 16 eyes with DR were enrolled. Images were acquired using a commercially available swept-source optical coherence tomography angiography (SS-OCTA) system. Three conditions were tested for each patient (hyperoxia, hypercapnia, and room-air) by employing a non-rebreathing apparatus that delivered appropriate gas mixtures (100% O 2 , 5% CO 2 , room air). Vessel skeleton density (VSD) and vessel diameter index (VDI) were compared between the conditions using mixed-model ANOVA adjusting for age and hypertension. Significant gas or interaction effects ...

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    18. Two-Year Risk of Exudation in Eyes with Non-Exudative AMD and Subclinical Neovascularization Detected with Swept Source OCT Angiography

      Two-Year Risk of Exudation in Eyes with Non-Exudative AMD and Subclinical Neovascularization Detected with Swept Source OCT Angiography

      Purpose Swept source optical coherence tomography angiography (SS-OCTA) was used to study the prevalence, incidence, and natural history of subclinical macular neovascularization (MNV) in eyes with unilateral non-exudative age-related macular degeneration (AMD). Design Prospective cohort study. Methods Patients were imaged using 3x3 mm and 6x6 mm SS-OCTA scan patterns. MNV was detected using the outer retina to choriocapillaris en face slab. Prevalence and incidence of subclinical MNV, Kaplan-Meier cumulative estimates for the overall risk of exudation, and the association between neovascular lesion size and the risk of exudation were assessed through 2 years. Results From August 2014 through March 2018 ...

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    19. Optical coherence tomography correlates multiple measures of tissue damage following acute burn injury

      Optical coherence tomography correlates multiple measures of tissue damage following acute burn injury

      Background: The visual assessment of burned skin is inherently subjective, and whilst a number of imaging modalities have identified quantifiable parameters to characterize vascular and structural changes following burn damage, none have become common place in the assessment protocol. Here, we use optical coherence tomography (OCT)-based angiography (OCTA) to introduce novel correlations between vessel depth, i.e., the depth of functional blood vessels beneath the tissue surface, edema depth, i.e., the depth of interstitial fluid buildup beneath the tissue surface, and tissue injury depth, i.e., the depth of collagen denaturation beneath the tissue surface, following burn injury ...

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    20. Revealing the morphology and function of the cochlea and middle ear with optical coherence tomography

      Revealing the morphology and function of the cochlea and middle ear with optical coherence tomography

      Optical coherence tomography (OCT) has revolutionized physiological studies of the hearing organ, the vibration and morphology of which can now be measured without opening the surrounding bone. In this review, we provide an overview of OCT as used in the otological research, describing advances and different techniques in vibrometry, angiography, and structural imaging.

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    21. Visualizing choriocapillaris using swept-source optical coherence tomography angiography with various probe beam sizes

      Visualizing choriocapillaris using swept-source optical coherence tomography angiography with various probe beam sizes

      Imaging choriocapillaris (CC) is a long-term challenge for commercial OCT angiography (OCTA) systems due to limited transverse resolution. Effects of transverse resolution on the visualization of a CC microvascular network are explored and demonstrated in this paper. We use three probe beams with sizes of ~1.12 mm, ~2.51 mm and ~3.50 mm at the pupil plane, which deliver an estimated transverse resolution at the retina of 17.5 µm, 8.8 µm and 7.0 µm, respectively, to investigate the ability of OCTA to resolve the CC capillary vessels. The complex optical microangiography algorithm is applied to ...

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    22. Effect of Scan Size on Glaucoma Diagnostic Performance Using OCT Angiography En Face Images of the Radial Peripapillary Capillaries

      Effect of Scan Size on Glaucoma Diagnostic Performance Using OCT Angiography En Face Images of the Radial Peripapillary Capillaries

      Precis: When comparing 4.5×4.5 mm to 6.0×6.0 mm optical coherence tomography angiography scans of the radial peripapillary capillaries (RPCs) for glaucoma diagnostic capability, there was a trend of 4.5 scans outperforming 6.0 scans, especially for inferior, nasal, and superior quadrants. Objectives: The main purpose of this study was to compare diagnostic ability of peripapillary vessel parameters from 4.5×4.5 mm (4.5) and 6.0×6.0 mm (6.0) spectral-domain optical coherence tomography angiography scans of the RPC in detecting primary open-angle glaucoma from nonglaucoma eyes. Methods: Consecutive patients ...

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    23. Quantitative evaluation of primary retinitis pigmentosa patients using colour Doppler flow imaging and optical coherence tomography angiography

      Quantitative evaluation of primary retinitis pigmentosa patients using colour Doppler flow imaging and optical coherence tomography angiography

      Purpose To find the potential relation between changes in retinal large vessels and terminal vessels using colour Doppler flow imaging (CDFI) and optical coherence tomography angiography (OCTA) and to compare the respective advantages of CDFI and OCTA in evaluating vascular changes in retinitis pigmentosa (RP) patients. Methods A prospective series of case study was conducted to enrol RP patients and age‐matched controls, who were, respectively, imaged by CDFI and OCTA. Repeatability and reproducibility of both CDFI and OCTA were performed among healthy volunteers. The central retinal artery (CRA) was detected by CDFI analysis to provide parameters of peak systolic ...

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    24. The evaluation of spontaneous Descemet’s membrane reattachment using swept-source optical coherence tomography: a case report

      The evaluation of spontaneous Descemet’s membrane reattachment using swept-source optical coherence tomography: a case report

      A 29-year old man presented with a history of facial burn in August of 2017. Slit lamp examination revealed significant central corneal stromal scarring in the right eye. The patient received deep anterior lamellar keratoplasty (DALK) in the right eye. Three weeks post operatively, the patient was found to have recurrent corneal edema on slit lamp exam, and standard anterior segment optical coherence tomography (OCT) revealed a central detachment of Descemet’s membrane.

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    1. (251 articles) Ruikang K. Wang
    2. (211 articles) University of Washington
    3. (54 articles) Oregon Health & Science University
    4. (27 articles) Lin An
    5. (23 articles) Woo June Choi
    6. (23 articles) Carl Zeiss Meditec
    7. (20 articles) Zhongwei Zhi
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