1. Articles from Ruikang K. Wang

    1-24 of 239 1 2 3 4 5 6 7 8 9 10 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. Optic Nerve Head Perfusion Before and After Intravitreal Antivascular Growth Factor Injections Using Optical Coherence Tomography-based Microangiography

      Optic Nerve Head Perfusion Before and After Intravitreal Antivascular Growth Factor Injections Using Optical Coherence Tomography-based Microangiography

      Purpose: To use optical coherence tomography angiography (OCTA) to evaluate the changes in optic nerve head perfusion following intravitreal antivascular endothelial growth factor injections. Methods: Preinjection and postinjection intraocular pressure (IOP) and OCTA images were taken of both the injected and uninjected fellow eyes. Results: Mean preinjection IOP was 16.6±4.7 mm Hg, which increased to a mean of 40.3±13.0 mm Hg ( P <0.0001) during the first postinjection image and remained elevated at 36.1±11.5 mm Hg ( P <0.0001) during the second postinjection image. Although no significant change was observed in ...

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    12. Correlations Between Choriocapillaris Flow Deficits Around Geographic Atrophy and Enlargement Rates Based on Swept Source OCT Imaging

      Correlations Between Choriocapillaris Flow Deficits Around Geographic Atrophy and Enlargement Rates Based on Swept Source OCT Imaging

      Purpose To determine the possible correlation between the annual enlargement rates (ERs) of geographic atrophy (GA) with the percentage and size of the choriocapillaris (CC) flow deficits (FDs) surrounding GA, measured with swept source optical coherence tomography angiography (SS-OCTA) images. Design Prospective, observational case series. Participants Patients with GA secondary to non-exudative AMD. Methods Patients were imaged with a 100-kHz SS-OCTA instrument (PLEX Elite 9000, Carl Zeiss Meditec) using a 6x6 mm field of view scan pattern. GA area measurements were obtained from en face SS-OCT sub-RPE slab images. Visualization of the CC and quantification of FDs were performed using ...

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    13. Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Cerebral ischemic stroke causes injury to brain tissue characterized by a complex cascade of neuronal and vascular events. Imaging during early stages of its development allows prediction of tissue infarction and penumbra, so that optimal intervention can be determined in order to salvage brain function impairment. Therefore, there is a critical need for novel imaging techniques that can characterize brain injury in the earliest phases of ischemic stroke. This study examined optical coherence tomography (OCT) for imaging acute injury in experimental ischemic stroke in vivo. Based on endogenous optical scattering signals provided by OCT imaging, we have developed a single ...

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    14. Diagnostic Performance of Macular Versus Peripapillary Vessel Parameters by Optical Coherence Tomography Angiography for Glaucoma

      Diagnostic Performance of Macular Versus Peripapillary Vessel Parameters by Optical Coherence Tomography Angiography for Glaucoma

      Purpose : To compare the diagnostic ability of the vessel parameters in macular and peripapillary regions measured using spectral-domain optical coherence tomography angiography (SD-OCTA) in differentiating primary open-angle glaucoma (POAG) from healthy eyes. Methods : POAG patients and healthy subjects underwent 6 × 6-mm scans centered on the macula and optic nerve head. Commercially available automatic segmentation created en face images from SD-OCTA of the superficial retinal layer (SRL) of the macular (m) and peripapillary (cp) regions. Vessel area density (VAD), vessel skeleton density (VSD), vessel complexity index (VCI), and flux were calculated. Area under curve (AUC) statistics controlled for age and intereye ...

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    15. Imaging and visualization of the polarization state of the probing beam in polarization-sensitive optical coherence tomography

      Imaging and visualization of the polarization state of the probing beam in polarization-sensitive optical coherence tomography

      We propose a simple and efficient method of color-encoded Stokes parameters to visualize the polarization states for polarization-sensitive optical coherence tomography (PS-OCT) of biological tissue. In this method, polarization states of the probing light are detected and described in the Stokes domain. Three primary colors of red, green, and blue are used to code Stokes parameters of Q, U, and V, respectively, which can be used to represent and visualize each unique polarization state. A strategy that uses the polarization state as the PS-OCT imaging parameter is first introduced to obtain high contrast images of the birefringent samples. Then, color-based ...

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    16. Attenuation correction assisted automatic segmentation for assessing choroidal thickness and vasculature with swept-source OCT

      Attenuation correction assisted automatic segmentation for assessing choroidal thickness and vasculature with swept-source OCT

      Swept source optical coherence tomography (SS-OCT) is being used more widely in clinical studies to investigate the choroid due to its deeper penetration under the retinal pigment epithelium and improved image quality compared with spectral domain OCT. However, automatic methods to reliably assess choroidal thickness and vasculature are still limited. This paper reports an approach that applies attenuation correction on SS-OCT structural scans to facilitate accurate automatic segmentation of the choroid and provides visualization of the choroidal vasculature without the necessity of OCT angiography. After attenuation correction, enhanced interlayer contrast at the choroidal-scleral interface was observed (from 0.13 ± 0 ...

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    17. Peripapillary microvasculature in the retinal nerve fiber layer in glaucoma by optical coherence tomography angiography: focal structural and functional correlations and diagnostic performance

      Peripapillary microvasculature in the retinal nerve fiber layer in glaucoma by optical coherence tomography angiography: focal structural and functional correlations and diagnostic performance

      Purpose: To quantify peripapillary microvasculature within the retinal nerve fiber layer (RNFL) in primary open-angle glaucoma (POAG) and normal eyes, determine association of perfusion parameters with structural and functional measures, and report diagnostic accuracy of perfusion parameters. Patients and methods: POAG and normal patients underwent 6×6 mm2 optic nerve head scans (Angioplex optical coherence tomography angiography [OCTA]; Cirrus HD-OCT 5000) and Humphrey Field Analyzer II-i 24-2 visual field (VF) testing. Prototype software performed semiautomatic segmentation to create RNFL en face images and quantified vessel area density (VAD), vessel skeleton density (VSD), and vessel complexity index (VCI) in the optic ...

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    18. Ultra-wide optical coherence tomography angiography in diabetic retinopathy

      Ultra-wide optical coherence tomography angiography in diabetic retinopathy

      Background: To implement an ultra-wide optical coherence tomography angiography imaging (UW-OCTA) modality in eyes with diabetic retinopathy (DR) with the aim of quantifying the burden of microvascular disease at baseline and subsequent clinic visits. Methods: UW-OCTA was implemented on a 1,060 nm swept source (SS) OCTA engine running at 100 kHz A-line rate with a motion tracking mechanism. A montage scanning protocol was used to capture a 100-degree field of view (FOV) using a 4×4 grid of sixteen total individual 6×6 mm 2 scans. Typical OCTA images with a FOV of 3×3, 6×6 and 12 ...

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    19. Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Penetrating vessels bridge the mesh of communicating vessels on the surface of the cortex with the subsurface microvascular beds that feed the underlying neural tissue. Their accurate identification in vivo is important in the investigations of neural degenerative diseases, e.g., Alzheimer's disease and stroke. Here, we propose an efficient method to automatically map cortical penetrating vessels based on an eigen decompensation analysis of the optical coherence tomography (OCT) and OCT angiographic signals. We first project the ensemble of repeated OCT signals into a feature space that represents the power spectral components of eigenvectors through a well-known eigen-decomposition method ...

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    20. Use of En Face Swept-Source Optical Coherence Tomography Angiography in Identifying Choroidal Flow Voids in 3 Patients With Birdshot Chorioretinopathy

      Use of En Face Swept-Source Optical Coherence Tomography Angiography in Identifying Choroidal Flow Voids in 3 Patients With Birdshot Chorioretinopathy

      Importance Patients with birdshot chorioretinopathy (BSCR) can experience a delay in diagnosis owing to the challenges of identifying the condition prior to evolution of characteristic choroidal scars. An objective, noninvasive method for detecting early lesions in BSCR might have an effect on preventing vision loss in these patients. Objective To test the feasibility of swept-source optical coherence tomography angiography (SS-OCTA) in the detection of BSCR choroidal lesions and to use en face image analysis of choroidal layers to localize lesion depth. Design, Setting, and Participants Prospective, longitudinal, observational case series of 3 patients diagnosed as having BSCR at 1 of ...

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    21. A non‐invasive imaging and measurement using optical coherence tomography angiography for the assessment of gingiva: An in vivo study

      A non‐invasive imaging and measurement using optical coherence tomography angiography for the assessment of gingiva: An in vivo study

      Gingiva is the soft tissue that surrounds and protects the teeth. Healthy gingiva provides an effective barrier to periodontal insults to deeper tissue, thus is an important indicator to a patient’s periodontal health. Current methods in assessing gingival tissue health, including visual observation and physical examination with probing on the gingiva, are qualitative and subjective. They may become cumbersome when more complex cases are involved, such as variations in gingival biotypes where feature and thickness of the gingiva are considered. A non‐invasive imaging technique providing depth‐resolved structural and vascular information is necessary for an improved assessment of ...

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    22. Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

      Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

      Background There are two forms of system implementation of optical coherence tomography angiography (OCTA) in ophthalmic imaging, i.e., spectral domain (SD-) and swept source OCTA (SS-OCTA). The purpose of this paper is to compare the SD-OCTA and SS-OCTA for elucidating structural and vascular features associated with central serous retinopathy (CSR), and to evaluate the effects of CSR on SD- and SS-OCTA’s imaging capabilities. Methods Normal subjects and CSR patients were imaged by SD- and SS-OCTA using 3 × 3 mm and 6 × 6 mm scan patterns. OCT signal strengths at the superficial retina, deep retina, Sattler’s layer and ...

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    23. Repeatability and Reproducibility of Quantitative Assessment of the Retinal Microvasculature Using Optical Coherence Tomography Angiography Based on Optical Microangiography

      Repeatability and Reproducibility of Quantitative Assessment of the Retinal Microvasculature Using Optical Coherence Tomography Angiography Based on Optical Microangiography

      Objective The aim of this study was to determine the repeatability and reproducibility of optical coherence tomography angiography (OCTA) based on optical microangiography (OMAG) measurements of macular vessels in normal eyes. Methods In this prospective cohort study, 40 eyes of 40 healthy volunteers underwent repeated OCTA (Cirrus HD-OCT 5000 angiography system, Carl Zeiss Meditec, Inc.) scans on two separate visit days. On each visit day, the eyes were scanned three times. The following parameters were used to quantitatively describe the OCTA images of the superficial vascular network: vessel area density (VAD), vessel skeleton density (VSD), vessel diameter index (VDI), vessel ...

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    24. Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography

      Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography

      Capillary velocity increases by 21% and velocity heterogeneity increases by 19% with older age. Abstract Normal aging is associated with significant alterations in brain’s vascular structure and function, which can lead to compromised cerebral circulation and increased risk of neurodegeneration. The in vivo examination of cerebral blood flow (CBF), including capillary beds, in aging brains with sufficient spatial detail remains challenging with current imaging modalities. In the present study, we use three-dimensional (3-D) quantitative optical coherence tomography angiography (OCTA) to examine characteristic differences of the cerebral vasculatures and hemodynamics at the somatosensory cortex (S1) between old (16-month-old) and young ...

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    1-24 of 239 1 2 3 4 5 6 7 8 9 10 »
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