1. Articles from Ruikang K. Wang

    1-24 of 311 1 2 3 4 ... 11 12 13 »
    1. Impact of Reticular Pseudodrusen on Choriocapillaris Flow Deficits and Choroidal Structure on Optical Coherence Tomography Angiography

      Impact of Reticular Pseudodrusen on Choriocapillaris Flow Deficits and Choroidal Structure on Optical Coherence Tomography Angiography

      Purpose: To examine the impact of reticular pseudodrusen (RPD) on choriocapillaris blood flow and choroidal structure in individuals with intermediate age-related macular degeneration (AMD). Methods: Individuals with bilateral large drusen underwent optical coherence tomography (OCT), color fundus photography, near-infrared reflectance, and fundus autofluorescence imaging to determine the presence of RPD. These participants also underwent swept-source OCT angiography (SS-OCTA) imaging to determine (1) choriocapillaris flow deficit (FD) parameters, including the percentage, mean size, and number of FDs present; and (2) choroidal structural parameters, including mean choroidal thickness and choroidal vascularity index. Differences in these parameters between eyes with and without coexistent ...

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    2. Change In Choriocapillaris Flow Deficits Within Tears Of The Retinal Pigment Epithelium Imaged With SWEPT-SOURCE Optical Coherence Tomography Angiography

      Change In Choriocapillaris Flow Deficits Within Tears Of The Retinal Pigment Epithelium Imaged With SWEPT-SOURCE Optical Coherence Tomography Angiography

      Purpose: Choriocapillaris (CC) flow deficits (FDs) were measured in the areas exposed by tears of the retinal pigment epithelium (RPE) before and after their onset to determine their change over time. Methods: Patients enrolled in a prospective, swept-source optical coherence tomography angiography (SS-OCTA) study were retrospectively reviewed for RPE tears, and scans were evaluated before and after RPE tear formation. Choriocapillaris flow deficits were measured within the bed of the tear and within a symmetric control region. Results: Three patients with RPE tears were imaged before tear formation and for at least 16 months afterward. When the baseline and first ...

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    3. Spatial resolution in optical coherence elastography of bounded media

      Spatial resolution in optical coherence elastography of bounded media

      Dynamic optical coherence elastography (OCE) tracks mechanical wave propagation in the subsurface region of tissue to image its shear modulus. For bulk shear waves, the lateral resolution of the reconstructed modulus map (i.e., elastographic resolution) can approach that of optical coherence tomography (OCT), typically a few tens of microns. Here we perform comprehensive numerical simulations and acoustic micro-tapping OCE experiments to show that for the typical situation of guided wave propagation in bounded media, such as cornea, the elastographic resolution cannot reach the OCT resolution and is mainly defined by the thickness of the bounded tissue layer. We considered ...

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    4. Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Non-Glaucoma Eyes

      Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Non-Glaucoma Eyes

      Précis: Peripapillary vessel parameters from optical coherence tomography angiography (OCTA) 4.5×4.5 mm scans in nonglaucomatous and glaucomatous eyes showed high repeatability and reproducibility, with higher reliability for commercially developed OCTA parameters compared with custom OCTA parameters. Purpose: The purpose of this study was to assess intrasession repeatability versus intersession reproducibility of peripapillary vessel parameters from 4.5×4.5 mm OCTA scans in nonglaucomatous eyes and glaucomatous eyes. Materials and Methods: In a longitudinal study, peripapillary OCTA scans were quantified using research-oriented custom quantification software that calculated vessel area density (VAD) and flux and clinic-oriented commercially ...

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    5. Local axis orientation mapped by polarization sensitive optical coherence tomography provides a unique contrast to identify caries lesions in enamel

      Local axis orientation mapped by polarization sensitive optical coherence tomography provides a unique contrast to identify caries lesions in enamel

      Due to rod-like hydroxyapatite crystal organizations, dental enamel is optically anisotropic, i.e., birefringent. Healthy enamel is known to be intrinsically negatively birefringent. However, when demineralization of enamel occurs, a considerable number of inter-crystallite spaces would be created between the crystallites in the enamel, which could lead to a sign reversion in birefringence of the enamel structure. We propose that this sign reversion can be leveraged in polarization sensitive OCT (PSOCT) imaging to differentiate early caries lesions from healthy enamel. In this study using PSOCT, we first confirm that the change in birefringence sign (negative to positive) can lead to ...

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    6. A deep learning model for automated segmentation of geographic atrophy imaged with swept-source optical coherence tomography images

      A deep learning model for automated segmentation of geographic atrophy imaged with swept-source optical coherence tomography images

      Purpose: To present a deep-learning algorithm for the segmentation of geographic atrophy (GA) using en face swept-source optical coherence tomography (SS-OCT) images that is accurate and reproducible for the assessment of GA growth over time. Design: Retrospective review of images obtained as part of a prospective natural history study Subjects: Patients with GA (90), early/intermediate AMD (32), healthy controls (16) METHODS: An automated algorithm utilizing scan volume data to generate three image inputs characterizing the main OCT features of GA - hyper-transmission in sub RPE slab, regions of RPE loss, and loss of retinal thickness - was trained with 126 images ...

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    7. Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      There remains a clinical need for an accurate and non-invasive imaging tool for intraoral evaluation of dental conditions. Optical coherence tomography (OCT) is a potential candidate to meet this need, but the design of current OCT systems limits their utility in the intraoral examinations. The inclusion of light-induced autofluorescence (LIAF) can expedite the image collection process and provides a large field of view for viewing the condition of oral tissues. This study describes a novel LIAF-OCT system equipped with a handheld probe designed for intraoral examination of microstructural (via OCT) and microvascular information (via OCT angiography, OCTA). The handheld probe ...

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    8. Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Nonglaucoma Eyes

      Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Nonglaucoma Eyes

      Prcis: Peripapillary vessel parameters from optical coherence tomography angiography (OCTA) 4.5×4.5 mm scans in nonglaucomatous and glaucomatous eyes showed high repeatability and reproducibility, with higher reliability for commercially developed OCTA parameters compared with custom OCTA parameters. Purpose: The purpose of this study was to assess intrasession repeatability versus intersession reproducibility of peripapillary vessel parameters from 4.5×4.5 mm OCTA scans in nonglaucomatous eyes and glaucomatous eyes. Materials and methods: In a longitudinal study, peripapillary OCTA scans were quantified using research-oriented custom quantification software that calculated vessel area density (VAD) and flux and clinic-oriented commercially developed ...

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    9. Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

      Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

      Purpose: To investigate the correlation between laser speckle flowgraphy (LSFG) signals and the quantitative metrics derived from optical coherence tomography (OCT) in normal eyes. Methods: LSFG, OCT, and OCT angiography (OCTA) imaging were performed on normal participants using a custom-designed LSFG system and a commercial swept-source OCT system. Mean (PWM) and amplitude (PWA) of the LSFG pulse waveform were selected to quantify the LSFG signals. Retinal and choroidal maps were obtained using the standard 6 × 6 mm OCT and OCTA scans. Structural and vascular metrics maps, including thickness, vessel area density, vessel skeleton density, and vessel diameter index of the ...

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    10. De-aliased depth-range-extended optical coherence tomography based on dual under-sampling

      De-aliased depth-range-extended optical coherence tomography based on dual under-sampling

      We demonstrate a dual under-sampling (DUS) method to achieve de-aliased and depth-range-extended optical coherence tomography (OCT) imaging. The spectral under-sampling can significantly reduce the data size but causes well-known aliasing artifacts. A change in the sampling frequency used to acquire the interference spectrum alters the aliasing period within the output window except for the true image; this feature is utilized to distinguish the true image from the aliasing artifacts. We demonstrate that with DUS, the data size is reduced to 37% at an extended depth range of 24 mm, over which the true depth can be precisely measured without ambiguity ...

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    11. Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      There remains a clinical need for an accurate and non-invasive imaging tool for intraoral evaluation of dental conditions. Optical coherence tomography (OCT) is a potential candidate to meet this need, but the design of current OCT systems limits their utility in the intraoral examinations. The inclusion of light-induced autofluorescence (LIAF) can expedite the image collection process and provides a large field of view for viewing the condition of oral tissues. This study describes a novel LIAF-OCT system equipped with a handheld probe designed for intraoral examination of microstructural (via OCT) and microvascular information (via OCT angiography, OCTA). The handheld probe ...

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    12. Automated counting of cerebral penetrating vessels using optical coherence tomography images of a mouse brain in vivo

      Automated counting of cerebral penetrating vessels using optical coherence tomography images of a mouse brain in vivo

      Rationale and objectives: Penetrating blood vessels emanating from cortical surface vasculature and lying deep in the cortex are essential vascular conduits for the shuttling of blood from superficial pial vessels to the capillary beds in parenchyma for the nourishment of neuronal brain tissues. Locating and counting the penetrating vessels is beneficial for the quantification of a course of ischemia in blood occlusive events such as stroke. This paper seeks to demonstrate and validate a method for automated penetrating vessel counting that uses optical coherence tomography (OCT). Materials and methods: This paper proposes an OCT method that effectively identifies and grades ...

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    13. Mitigating the effects of choroidal hyper- and hypo-transmission defects on choroidal vascularity index assessments using optical coherence tomography

      Mitigating the effects of choroidal hyper- and hypo-transmission defects on choroidal vascularity index assessments using optical coherence tomography

      Background: Changes in choroidal vascularity index (CVI) are associated with multiple choroid-related ocular diseases. CVI is calculated as the area/volume ratio of vessels in the choroid, which could be affected by alterations in regional signal intensities due to hypo-transmission defects (hypoTDs) caused by drusen and retinal pigment epithelium (RPE) detachments, and hyper-transmission defects (hyperTDs) caused by the absence of RPE. To develop a simulation model to verify the CVI assessments in eyes with hyper/hypoTDs and demonstrate that accurate CVIs can be achieved after attenuation correction on swept-source optical coherence tomography (SS-OCT). Methods: A simulation model was developed on ...

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    14. Swept-Source Optical Coherence Tomography Detection of Bruch’s Membrane and Choriocapillaris Abnormalities in Sorsby Macular Dystrophy

      Swept-Source Optical Coherence Tomography Detection of Bruch’s Membrane and Choriocapillaris Abnormalities in Sorsby Macular Dystrophy

      Purpose: Swept-source optical coherence tomography angiography (SS-OCTA) was used to analyze Bruch's membrane (BM) and choriocapillaris (CC) abnormalities in undiagnosed family members with Sorsby macular dystrophy (SMD). Methods: In a family with SMD (TIMP3 Tyr191Cys), SS-OCTA imaging was performed using the 6X6mm scan patter and previously validated algorithms to detect abnormalities in BM and the CC, as well as the presence of reticular pseudodrusen (RPD) and macular neovascularization (MNV). Genetic analyses were performed for TIMP3 mutations. Results: Of eight family members, two were previously diagnosed with SMD and six were asymptomatic. SS-OCTA imaging of the 33-year-old proband revealed type ...

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    15. Imaging-photoplethysmography-guided optical microangiography

      Imaging-photoplethysmography-guided optical microangiography

      We report a method to image facial cutaneous microvascular perfusion using wide-field imaging photoplethysmography (iPPG) and handheld swept-source optical coherence tomography (OCT). The iPPG system employs a 16-bit-depth camera to provide a 2D wide-field blood pulsation map that is then used as a positioning guidance for OCT imaging of cutaneous microvasculature. We show the results from iPPG and OCT to demonstrate the ability of guided imaging of cutaneous microvasculature, which is potentially useful for the assessment of skin conditions in dermatology and cosmetology.

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    16. Automatic geographic atrophy segmentation using optical attenuation in OCT scans with deep learning

      Automatic geographic atrophy segmentation using optical attenuation in OCT scans with deep learning

      A deep learning algorithm was developed to automatically identify, segment, and quantify geographic atrophy (GA) based on optical attenuation coefficients (OACs) calculated from optical coherence tomography (OCT) datasets. Normal eyes and eyes with GA secondary to age-related macular degeneration were imaged with swept-source OCT using 6 × 6 mm scanning patterns. OACs calculated from OCT scans were used to generate customized composite en face OAC images. GA lesions were identified and measured using customized en face sub-retinal pigment epithelium (subRPE) OCT images. Two deep learning models with the same U-Net architecture were trained using OAC images and subRPE OCT images. Model ...

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    17. Intrasession Repeatability and Intersession Reproducibility of Macular Vessel Parameters on Optical Coherence Tomography Angiography in Glaucomatous and Non-Glaucomatous Eyes

      Intrasession Repeatability and Intersession Reproducibility of Macular Vessel Parameters on Optical Coherence Tomography Angiography in Glaucomatous and Non-Glaucomatous Eyes

      Purpose: Using optical coherence tomography angiography (OCTA), this study compared intrasession repeatability versus intersession reproducibility of macular vessel parameters in glaucoma and non-glaucoma subjects. Methods: 6x6 mm 2 macular OCTA scans (Cirrus HD-OCT 5000) were acquired from glaucomatous and non-glaucomatous subjects as part of an observational, longitudinal study. Vessel area density (VAD) and vessel skeleton density (VSD) were calculated using research-based quantification software while perfusion density (PD Z ) and vessel density (VD Z ) were calculated using commercially developed software (Cirrus 11.0, Carl Zeiss Meditec). Intrasession repeatability and intersession reproducibility were determined using within-eye standard deviation (S W ), within-eye coefficient ...

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    18. Probing elastic anisotropy of human skin in vivo with light using non-contact acoustic micro-tapping OCE and polarization sensitive OCT

      Probing elastic anisotropy of human skin in vivo with light using non-contact acoustic micro-tapping OCE and polarization sensitive OCT

      Skin broadly protects the human body from undesired factors such as ultraviolet radiation and abrasion and helps conserve body temperature and hydration. Skin’s elasticity and its level of anisotropy are key to its aesthetics and function. Currently, however, treatment success is often speculative and subjective, and is rarely based on skin’s elastic properties because there is no fast and accurate non-contact method for imaging of skin’s elasticity.

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    19. OCTA Derived Vessel Skeleton Density Versus Flux and Their Associations With Systemic Determinants of Health

      OCTA Derived Vessel Skeleton Density Versus Flux and Their Associations With Systemic Determinants of Health

      Purpose: To examine the associations of optical coherence tomography angiography (OCTA)-derived retinal capillary flux with systemic determinants of health. Methods: This is a cross-sectional study of subjects recruited from the African American Eye Disease Study. A commercially available swept-source (SS)-OCTA device was used to image the central 3 × 3 mm macular region. Retinal capillary perfusion was assessed using vessel skeleton density (VSD) and flux. Flux approximates the number of red blood cells moving through vessel segments and is a novel metric, whereas VSD is a previously validated measure commonly used to quantify capillary density. The associations of OCTA ...

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    20. Capillary density and caliber as assessed by optical coherence tomography angiography may be significant predictors of diabetic retinopathy severity

      Capillary density and caliber as assessed by optical coherence tomography angiography may be significant predictors of diabetic retinopathy severity

      Purpose To validate retinal capillary density and caliber associations with diabetic retinopathy (DR) severity in different clinical settings. Methods This cross-sectional study assessed retinal capillary density and caliber in the superficial retinal layer of 3-mm OCTA scans centered on the fovea. Images were collected from non-diabetic controls and subjects with mild or referable DR (defined DR worse than mild DR) between February 2016 and December 2019 at secondary and tertiary eye care centers. Vessel Skeleton Density (VSD), a measure of capillary density, and Vessel Diameter Index (VDI), a measure of vascular caliber, were calculated from these images. Discriminatory performance of ...

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    21. Interocular asymmetry of choroidal thickness and vascularity index measurements in normal eyes assessed by swept-source optical coherence tomography

      Interocular asymmetry of choroidal thickness and vascularity index measurements in normal eyes assessed by swept-source optical coherence tomography

      Background: To investigate the symmetry of interocular choroidal thickness and vascularity index measurements in normal eyes using swept-source optical coherence tomography (SS-OCT). Cross-sectional and observational study. This study included 244 eyes of 122 normal adults with ages uniformly distributed from 19 to 89 years. Methods: SS-OCT imaging was performed using a scanning pattern of 12×12 mm. Mean choroidal thickness (MCT) and choroidal vascularity index (CVI) measurements in the entire scanning region were obtained using a validated and published automatic method. The correlation and differences (including signed and absolute differences) between bilateral MCT and CVI measurements were analyzed at the ...

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    22. Vitreous opacities in infants born full-term and preterm by handheld swept-source optical coherence tomography

      Vitreous opacities in infants born full-term and preterm by handheld swept-source optical coherence tomography

      Purpose To compare vitreous opacity density in infants born at term and in infants born prematurely using an investigational handheld swept-source optical coherence tomography (SS-OCT). Methods Infants born at term underwent imaging once between 12 and 48 hours after birth; infants born prematurely were imaged at each routine retinopathy of prematurity (ROP) examination. Three masked, trained graders analyzed images. Semiautomated methods were used to quantify vitreous opacity density, which was correlated with ROP severity based on indirect ophthalmoscopy, other SS-OCT findings, and medical comorbidities. Results Between April 2018 and June 2019, 251 SS-OCT imaging sessions were performed on 78 infants ...

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    23. Polarization sensitive optical coherence tomography with single input for imaging depth-resolved collagen organizations

      Polarization sensitive optical coherence tomography with single input for imaging depth-resolved collagen organizations

      Collagen organization plays an important role in maintaining structural integrity and determining tissue function. Polarization-sensitive optical coherence tomography (PSOCT) is a promising noninvasive three-dimensional imaging tool for mapping collagen organization in vivo. While PSOCT systems with multiple polarization inputs have demonstrated the ability to visualize depth-resolved collagen organization, systems, which use a single input polarization state have not yet demonstrated sufficient reconstruction quality. Herein we describe a PSOCT based polarization state transmission model that reveals the depth-dependent polarization state evolution of light backscattered within a birefringent sample. Based on this model, we propose a polarization state tracing method that relies ...

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