1. Articles from Ruikang K. Wang

    1-24 of 228 1 2 3 4 5 6 7 8 9 10 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. Automated three‐dimensional cell counting method for grading uveitis of rodent eye in vivo with optical coherence tomography

      Automated three‐dimensional cell counting method for grading uveitis of rodent eye in vivo with optical coherence tomography

      In preclinical vision research, cell grading in small animal models is essential for the quantitative evaluation of intraocular inflammation. Here, we present a new and practical optical coherence tomography (OCT) image analysis method for the automated detection and counting of aqueous cells in the anterior chamber (AC) of a rodent model of uveitis. Anterior segment OCT images are acquired with a 100 kHz swept‐source OCT system. The proposed method consists of 2 steps. In the first step, we first despeckle and binarize each OCT image. After removing AS structures in the binary image, we then apply area thresholding to ...

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    15. OCT‐based angiography of human dermal microvascular reactions to local stimuli: Implications for increasing capillary blood collection volumes

      OCT‐based angiography of human dermal microvascular reactions to local stimuli: Implications for increasing capillary blood collection volumes

      Objectives To measure and compare microvascular responses within the skin of the upper arm to local stimuli, such as heating or rubbing, through the use of optical coherence tomography angiography (OCTA), and to investigate its impact on blood volume collection. Materials and Methods With the use of heat packs or rubbing, local stimulation was applied to the skin of either the left or right upper arm. Data from the stimulated sites were obtained using OCTA comparing pre‐ and post‐stimulation microvascular parameters, such as vessel density, mean vessel diameter, and mean avascular pore size. Additionally, blood was collected using a ...

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    16. Optical coherence tomography angiography monitors human cutaneous wound healing over time

      Optical coherence tomography angiography monitors human cutaneous wound healing over time

      Background: In vivo imaging of the complex cascade of events known to be pivotal elements in the healing of cutaneous wounds is a difficult but essential task. Current techniques are highly invasive, or lack the level of vascular and structural detail required for accurate evaluation, monitoring and treatment. We aimed to use an advanced optical coherence tomography (OCT)-based angiography (OCTA) technique for the non-invasive, high resolution imaging of cutaneous wound healing. Methods: We used a clinical prototype OCTA to image, identify and track key vascular and structural adaptations known to occur throughout the healing process. Specific vascular parameters, such ...

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    17. Generating​ ​retinal​ ​flow​ ​maps​ ​from​ ​structural​ ​optical​ ​coherence​ ​tomography​ ​with​ ​artificial intelligence

      Generating​ ​retinal​ ​flow​ ​maps​ ​from​ ​structural​ ​optical​ ​coherence​ ​tomography​ ​with​ ​artificial intelligence

      Despite advances in artificial intelligence (AI), its application in medical imaging has been burdened and limited by expert-generated labels. We used images from optical coherence tomography angiography (OCTA), a relatively new imaging modality that measures retinal blood flow, to train an AI algorithm to generate flow maps from standard optical coherence tomography (OCT) images, exceeding the ability and bypassing the need for expert labeling. Deep learning was able to infer flow from single structural OCT images with similar fidelity to OCTA and significantly better than expert clinicians (P < 0.00001). Our model allows generating flow maps from large volumes of ...

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    18. Generating perfusion maps from structural optical coherence tomography with artificial intelligence

      Generating perfusion maps from structural optical coherence tomography with artificial intelligence

      Despite significant advances in artificial intelligence (AI) for computer vision, its application in medical imaging has been limited by the burden and limits of expert-generated labels. We used images from optical coherence tomography angiography (OCTA), a relatively new imaging modality that measures perfusion of the retinal vasculature, to train an AI algorithm to generate vasculature maps from standard structural optical coherence tomography (OCT) images of the same retinae, both exceeding the ability and bypassing the need for expert labeling. Deep learning was able to infer perfusion of microvasculature from structural OCT images with similar fidelity to OCTA and significantly better ...

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    19. Optical coherence tomography angiography and cutaneous wound healing

      Optical coherence tomography angiography and cutaneous wound healing

      Background: Examination of the skin’s vascular and structural features is essential in clinical, medical, and research dermatology. However, there is a lack of comprehensive imaging tools that clearly and accurately evaluates the skin’s vascular and structural features. Current techniques are invasive and have inherent preparatory drawbacks. Aim: To use optical coherence tomography angiography (OCTA) for a more accurate depiction of vessels in the skin without the use of a dye or other invasive techniques to visualize and asses the role of the skin’s vasculature during the process’ of wound healing. Method: We used an in-house-built, swept source-OCT ...

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    20. Optical Coherence Tomography Microangiography Imaging of Circumscribed Choroidal Hemangioma

      Optical Coherence Tomography Microangiography Imaging of Circumscribed Choroidal Hemangioma

      Optical coherence tomography angiography (OCTA) is a new imaging technology capable of providing three-dimensional (3-D) retinal and choroidal microvascular maps without a need for exogenous dye. In this study, the authors evaluate the retinal and choroidal microvascular architecture of the macula in a patient with choroidal hemangioma using OCTA. Widefield OCTA with tracking capability and segmentation was performed to provide images with a field of view at 9 × 9 mm 2 . The en face maximum projection was used to generate 2-D angiograms of different layers with color-coded images. Variable levels of perfusion within the lesion were identified, which correlate well ...

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    21. Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions

      Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions

      Background In clinical dermatology, the identification of subsurface vascular and structural features known to be associated with numerous cutaneous pathologies remains challenging without the use of invasive diagnostic tools. Objective To present an advanced optical coherence tomography angiography (OCTA) method to directly visualize capillary-level vascular and structural features within skin in vivo . Methods An advanced OCTA system with a 1310 nm wavelength was used to image the microvascular and structural features of various skin conditions. Subjects were enrolled and OCTA imaging was performed with a field of view of approximately 10 × 10 mm. Skin blood flow was identified using an ...

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    22. Methods and systems for integrated imaging using optical coherence tomography and photoacoustic imaging

      Methods and systems for integrated imaging using optical coherence tomography and photoacoustic imaging

      Systems and methods for photoacoustic imaging are provided. Photoacoustic signals are excited from a body and the excited photoacoustic signals are detected with a low coherence interferometer system serving as a photoacoustic detector. Cross-sectional images of the body are then reconstructed by the system from the detected photoacoustic signals.

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    23. Long ranging swept-source optical coherence tomography-based angiography outperforms its spectral-domain counterpart in imaging human skin microcirculations

      Long ranging swept-source optical coherence tomography-based angiography outperforms its spectral-domain counterpart in imaging human skin microcirculations

      There is an increasing demand for imaging tools in clinical dermatology that can perform in vivo wide-field morphological and functional examination from surface to deep tissue regions at various skin sites of the human body. The conventional spectral-domain optical coherence tomography-based angiography (SD-OCTA) system is difficult to meet these requirements due to its fundamental limitations of the sensitivity roll-off, imaging range as well as imaging speed. To mitigate these issues, we demonstrate a swept-source OCTA (SS-OCTA) system by employing a swept source based on a vertical cavity surface-emitting laser. A series of comparisons between SS-OCTA and SD-OCTA are conducted. Benefiting ...

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    24. Multifunctional in vivo imaging for monitoring wound healing using swept-source polarization-sensitive optical coherence tomography

      Multifunctional in vivo imaging for monitoring wound healing using swept-source polarization-sensitive optical coherence tomography

      Background and Objective Wound healing involves a complex and dynamic biological process in response to tissue injury. Monitoring of the cascade of cellular events is useful for wound management and treatment. The aim of this study is to demonstrate the potential of multifunctional polarization-sensitive optical coherence tomography (PS-OCT) to longitudinally monitor the self-healing process in a murine cutaneous wound model. Materials and Methods A multi-functional PS-OCT system based on swept source OCT configuration (1,310 nm central wavelength) was designed to obtain simultaneously microstructural, blood perfusion, and birefringent information of a biological tissue in vivo . A 1-mm-diameter wound was generated ...

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    1. (228 articles) Ruikang K. Wang
    2. (188 articles) University of Washington
    3. (53 articles) Oregon Health & Science University
    4. (27 articles) Lin An
    5. (22 articles) Woo June Choi
    6. (20 articles) Zhongwei Zhi
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    8. (16 articles) Alfred L. Nuttall
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