1. Articles from Wang-Yuhl Oh

    1-24 of 36 1 2 »
    1. Comprehensive Assessment of High-Risk Plaques by Dual-Modal Imaging Catheter in Coronary Artery

      Comprehensive Assessment of High-Risk Plaques by Dual-Modal Imaging Catheter in Coronary Artery

      Coronary plaque destabilization involves alterations in microstructure and biochemical composition; however, no imaging approach allows such comprehensive characterization. Herein, the authors demonstrated a simultaneous microstructural and biochemical assessment of high-risk plaques in the coronary arteries in a beating heart using a fully integrated optical coherence tomography and fluorescence lifetime imaging (FLIm). It was found that plaque components such as lipids, macrophages, lipids+macrophages, and fibrotic tissues had unique fluorescence lifetime signatures that were distinguishable using multispectral FLIm. Because FLIm yielded massive biochemical readouts, the authors incorporated machine learning framework into FLIm, and ultimately, their approach enabled an automated, quantitative imaging ...

      Read Full Article
    2. Macrophage targeted theranostic strategy for accurate detection and rapid stabilization of the inflamed high-risk plaque

      Macrophage targeted theranostic strategy for accurate detection and rapid stabilization of the inflamed high-risk plaque

      Rationale: Inflammation plays a pivotal role in the pathogenesis of the acute coronary syndrome. Detecting plaques with high inflammatory activity and specifically treating those lesions can be crucial to prevent life-threatening cardiovascular events. Methods: Here, we developed a macrophage mannose receptor (MMR)-targeted theranostic nanodrug (mannose-polyethylene glycol-glycol chitosan-deoxycholic acid-cyanine 7-lobeglitazone; MMR-Lobe-Cy) designed to identify inflammatory activity as well as to deliver peroxisome proliferator-activated gamma (PPARγ) agonist, lobeglitazone, specifically to high-risk plaques based on the high mannose receptor specificity. The MMR-Lobe-Cy was intravenously injected into balloon-injured atheromatous rabbits and serial in vivo optical coherence tomography (OCT)-near-infrared fluorescence (NIRF) structural-molecular imaging ...

      Read Full Article
      Mentions: Korea University
    3. Robust and easy-to-operate stretched-pulse mode-locked wavelength-swept laser with an all-polarization-maintaining fiber cavity for 10 MHz A-line rate optical coherence tomography

      Robust and easy-to-operate stretched-pulse mode-locked wavelength-swept laser with an all-polarization-maintaining fiber cavity for 10 MHz A-line rate optical coherence tomography

      We demonstrate robust and easy-to-operate stretched-pulse mode-locked laser (SPML) architectures using all-polarization-maintaining fiber laser cavities. Because of the polarization-maintaining construction, the laser performance is unaffected by mechanical perturbation on the cavity fibers. The lasers automatically initiate linear-in-wavenumber sweeps across 100 nm centered at 1290 nm with a 10 MHz repetition rate. OCT imaging with a sensitivity of 98 dB and a single-sided 6 dB coherence length of 2.5 mm is demonstrated. OCT angiography of a mouse brain that visualized three-dimensional cerebral microvasculature over a field of 1.5 m m × 1.5 m m 1.5mm×1.5mm (398 ...

      Read Full Article
    4. Visualization of three-dimensional microcirculation of rodents’ retina and choroid for studies of critical illness using optical coherence tomography angiography

      Visualization of three-dimensional microcirculation of rodents’ retina and choroid for studies of critical illness using optical coherence tomography angiography

      We developed a method to measure the relative blood flow speed using optical coherence tomography angiography (OCTA) in retina and choroid, and investigated the feasibility of this method for assessing microcirculatory function in rat models of sepsis and hemorrhagic shock. Two sepsis models, 6-h severe sepsis without treatment and 30-h moderate sepsis maintaining mean arterial pressure, and volume controlled hemorrhagic shock and fluid resuscitation model were used to see the change of microcirculation. The blood flow index (BFI), which was calculated from the OCTA images to represent the average relative blood flow, was decreasing during the 6-h severe sepsis model ...

      Read Full Article
    5. Quantification of retinal microvascular parameters by severity of diabetic retinopathy using wide-field swept-source optical coherence tomography angiography

      Quantification of retinal microvascular parameters by severity of diabetic retinopathy using wide-field swept-source optical coherence tomography angiography

      Purpose: To investigate the diagnostic utility of microvascular parameters for grading the severity of diabetic retinopathy (DR) with a range of views using wide-field swept-source optical coherence tomography angiography (SS-OCTA). Methods: This retrospective study grouped 235 eyes with diabetes into the five grades: diabetes without retinopathy (no-DR), mild non-proliferative DR (NPDR), moderate NPDR, severe NPDR, and proliferative DR (PDR). Foveal avascular zone (FAZ) metrics, vessel density (VD), and the capillary nonperfusion area (NPA) were quantified with a customized, semiautomatic software algorithm. Regions of interest were selected from three rectangular fields of different sizes (i.e., 3 × 3 mm 2 , 6 ...

      Read Full Article
    6. Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

      Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

      Significance: Evaluation of vessel patency and blood flow direction is important in various medical situations, including diagnosis and monitoring of ischemic diseases, and image-guided vascular surgeries. While optical coherence tomography angiography (OCTA) is the most widely used functional extension of optical coherence tomography that visualizes three-dimensional vasculature, inability to provide information of blood flow direction is one of its limitations. Aim: We demonstrate two-dimensional (2D) transverse blood flow direction imaging in en face OCTA. Approach: A series of triangular beam scans for the fast axis was implemented in the horizontal direction for the first volume scan and in the vertical ...

      Read Full Article
    7. Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

      Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

      Significance: Evaluation of vessel patency and blood flow direction is important in various medical situations, including diagnosis and monitoring of ischemic diseases, and image-guided vascular surgeries. While optical coherence tomography angiography (OCTA) is the most widely used functional extension of optical coherence tomography that visualizes three-dimensional vasculature, inability to provide information of blood flow direction is one of its limitations. Aim: We demonstrate two-dimensional (2D) transverse blood flow direction imaging in en face OCTA. Approach: A series of triangular beam scans for the fast axis was implemented in the horizontal direction for the first volume scan and in the vertical ...

      Read Full Article
    8. High-speed optical coherence tomography angiography for the measurement of stimulus-induced retrograde vasodilation of cerebral pial arteries in awake mice

      High-speed optical coherence tomography angiography for the measurement of stimulus-induced retrograde vasodilation of cerebral pial arteries in awake mice

      Significance: Having a clear understanding of functional hyperemia is crucial for functional brain imaging and neurological disease research. Vasodilation induced by sensory stimulus propagates from the arterioles to the upstream pial arteries in a retrograde fashion. As retrograde vasodilation occurs briefly in the early stage of functional hyperemia, an imaging technique with a high temporal resolution is required for its measurement. Aim: We aimed to present an imaging method to measure stimulus-induced retrograde vasodilation in awake animals. Approach: An imaging method based on optical coherence tomography angiography, which enables a high-speed and label-free vessel diameter measurement, was developed and applied ...

      Read Full Article
    9. In vivo imaging of the hyaloid vascular regression and retinal and choroidal vascular development in rat eyes using optical coherence tomography angiography

      In vivo imaging of the hyaloid vascular regression and retinal and choroidal vascular development in rat eyes using optical coherence tomography angiography

      This study investigates the hyaloid vascular regression and its relationship to the retinal and choroidal vascular developments using optical coherence tomography angiography (OCTA). Normal and oxygen-induced retinopathy (OIR) rat eyes at postnatal day 15, 18, 21, and 24 were longitudinally imaged using OCTA. At each day, two consecutive imaging for visualizing the hyaloid vasculature and the retinal and choroidal vasculatures were conducted. The hyaloid vessel volume and the retinal and choroidal vessel densities were measured. The hyaloid vessel volumes gradually decreased during the regression, although the OIR eyes exhibited large vessel volumes at all time points. A spatial relationship between ...

      Read Full Article
    10. 9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking

      9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking

      In optical coherence tomography (OCT), high-speed systems based at 1300 nm are among the most broadly used. Here, we present 9.4 MHz A-line rate OCT system at 1300 nm. A wavelength-swept laser based on stretched-pulse active mode locking (SPML) provides a continuous and linear-in-wavenumber sweep from 1240 nm to 1340 nm, and the OCT system using this light source provides a sensitivity of 98 dB and a single-sided 6-dB roll-off depth of 2.5 mm. We present new capabilities of the 9.4 MHz SPML-OCT system in three microscopy applications. First, we demonstrate high quality OCTA imaging at a ...

      Read Full Article
    11. Retinal Blood Vessel Caliber Estimation for Optical Coherence Tomography Angiography Images Based on 3D Superellipsoid Modeling

      Retinal Blood Vessel Caliber Estimation for Optical Coherence Tomography Angiography Images Based on 3D Superellipsoid Modeling

      Changes of retinal blood vessel calibers may reflect various retinal diseases and even several non-retinal diseases. We propose a new method to estimate retinal vessel calibers from 3D optical coherence tomography angiography (OCTA) images based on 3D modeling using superellipsoids. Taking advantage of 3D visualization of the retinal tissue microstructures in vivo provided by OCTA, our method can detect retinal blood vessels precisely, estimate their calibers reliably, and show the relative flow speed visually.

      Read Full Article
    12. Tie2 activation promotes choriocapillary regeneration for alleviating neovascular age-related macular degeneration

      Tie2 activation promotes choriocapillary regeneration for alleviating neovascular age-related macular degeneration

      Choriocapillary loss is a major cause of neovascular age-related macular degeneration (NV-AMD). Although vascular endothelial growth factor (VEGF) blockade for NV-AMD has shown beneficial outcomes, unmet medical needs for patients refractory or tachyphylactic to anti-VEGF therapy exist. In addition, the treatment could exacerbate choriocapillary rarefaction, necessitating advanced treatment for fundamental recovery from NV-AMD. In this study, Tie2 activation by angiopoietin-2–binding and Tie2-activating antibody (ABTAA) presents a therapeutic strategy for NV-AMD. Conditional Tie2 deletion impeded choriocapillary maintenance, rendering eyes susceptible to NV-AMD development. Moreover, in a NV-AMD mouse model, ABTAA not only suppressed choroidal neovascularization (CNV) and vascular leakage but ...

      Read Full Article
    13. Comprehensive intravascular imaging of atherosclerotic plaque in vivo using optical coherence tomography and fluorescence lifetime imaging

      Comprehensive intravascular imaging of atherosclerotic plaque in vivo using optical coherence tomography and fluorescence lifetime imaging

      Comprehensive imaging of both the structural and biochemical characteristics of atherosclerotic plaque is essential for the diagnosis and study of coronary artery disease because both a plaque’s morphology and its biochemical composition affect the level of risk it poses. Optical coherence tomography (OCT) and fluorescence lifetime imaging (FLIm) are promising optical imaging methods for characterizing coronary artery plaques morphologically and biochemically, respectively. In this study, we present a hybrid intravascular imaging device, including a custom-built OCT/FLIm system, a hybrid optical rotary joint, and an imaging catheter, to visualize the structure and biochemical composition of the plaque in an ...

      Read Full Article
    14. Wide dynamic range high-speed three-dimensional quantitative OCT angiography with a hybrid-beam scan

      Wide dynamic range high-speed three-dimensional quantitative OCT angiography with a hybrid-beam scan

      We demonstrate a novel hybrid-beam scanning-based quantitative optical coherence tomography angiography (OCTA) that provides high-speed wide dynamic range blood flow speed imaging. The hybrid-beam scanning scheme enables multiple OCTA image acquisitions with a wide range of multiple time intervals simultaneously providing wide dynamic range blood flow speed imaging independent of the blood vessel orientation, which was quantified over a speed range of 0.6 ∼ 104    mm / s 0.6∼104  mm/s through the blood flow phantom experiments. A fully automated high-speed hybrid-beam scanning-based quantitative OCTA system demonstrates visualization of blood flow speeds in various vessels from the main arteries ...

      Read Full Article
    15. Multispectral analog-mean-delay fluorescence lifetime imaging combined with optical coherence tomography

      Multispectral analog-mean-delay fluorescence lifetime imaging combined with optical coherence tomography

      The pathophysiological progression of chronic diseases, including atherosclerosis and cancer, is closely related to compositional changes in biological tissues containing endogenous fluorophores such as collagen, elastin, and NADH, which exhibit strong autofluorescence under ultraviolet excitation. Fluorescence lifetime imaging (FLIm) provides robust detection of the compositional changes by measuring fluorescence lifetime, which is an inherent property of a fluorophore. In this paper, we present a dual-modality system combining a multispectral analog-mean-delay (AMD) FLIm and a high-speed swept-source optical coherence tomography (OCT) to simultaneously visualize the cross-sectional morphology and biochemical compositional information of a biological tissue. Experiments using standard fluorescent solutions showed ...

      Read Full Article
    16. Comparison of Accuracy of One Use Methods for Calculating Fractional Flow Reserve by Intravascular Optical Coherence Tomography to That Determined by the Pressure-Wire Method

      Comparison of Accuracy of One Use Methods for Calculating Fractional Flow Reserve by Intravascular Optical Coherence Tomography to That Determined by the Pressure-Wire Method

      While identification of hemodynamic significance of coronary lesions becomes important for revascularization strategy, the potential role of three-dimensional high-resolution intracoronary Optical coherence tomography (OCT) for predicting functional significance of coronary lesions remains unclear. We assessed the diagnostic performance of two computational approaches for deriving fractional flow reserve (FFR) from intravascular OCT images. We developed two methods to derive FFR from volumetric OCT images by applying analytical fluid dynamics (FFR-OCTAFD) and computational fluid dynamics (FFR-OCTCFD). Among 217 eligible patients between 2011 and 2014, total 104 patients were included for data analysis (9 for derivation, 95 for validation). Luminal geometries from three-dimensional ...

      Read Full Article
    17. Intravascular optical coherence tomography [Invited]

      Intravascular optical coherence tomography [Invited]

      Shortly after the first demonstration of optical coherence tomography for imaging the microstructure of the human eye, work began on developing systems and catheters suitable for intravascular imaging in order to diagnose and investigate atherosclerosis and potentially to monitor therapy. This review covers the driving considerations of the clinical application and its constraints, the major engineering milestones that enabled the current, high-performance commercial imaging systems, the key studies that laid the groundwork for image interpretation, and the clinical research that traces intravascular optical coherence tomography (OCT) from early human pilot studies to current clinical trials.

      Read Full Article
    18. Single cardiac cycle three-dimensional intracoronary optical coherence tomography

      Single cardiac cycle three-dimensional intracoronary optical coherence tomography

      While high-speed intracoronary optical coherence tomography (OCT) provides three-dimensional (3D) visualization of coronary arteries in vivo , imaging speeds remain insufficient to avoid motion artifacts induced by heartbeat, limiting the clinical utility of OCT. In this paper, we demonstrate development of a high-speed intracoronary OCT system (frame rate: 500 frames/s, pullback speed: 100 mm/s) along with prospective electrocardiogram (ECG) triggering technology, which enabled volumetric imaging of long coronary segments within a single cardiac cycle (70 mm pullback in 0.7 s) with minimal cardiac motion artifact. This technology permitted detailed visualization of 3D architecture of the coronary arterial wall ...

      Read Full Article
    19. Imaging Laser-Induced Choroidal Neovascularization in the Rodent Retina Using Optical Coherence Tomography Angiography

      Imaging Laser-Induced Choroidal Neovascularization in the Rodent Retina Using Optical Coherence Tomography Angiography

      Purpose : The purpose of this study was to evaluate the performance of optical coherence tomography angiography (OCTA) in visualizing laser-induced choroidal neovascularization (CNV) in the rodent retina. Methods : Choroidal neovascularization was induced via laser photocoagulation in 2 male Brown Norway rats and 2 male C57BL/6 mice. For qualitative comparison, the animals were imaged in vivo with OCTA, indocyanine green angiography (ICGA), and fluorescein angiography (FA), and ex vivo with immunofluorescence confocal microscopy, 14 days post laser photocoagulation without anti-vascular endothelial growth factor (anti-VEGF) intervention. For longitudinal quantitative analysis, CNV was induced in 6 additional male C57BL/6 mice. Three ...

      Read Full Article
    20. Characterization of lipid-rich plaques using spectroscopic optical coherence tomography

      Characterization of lipid-rich plaques using spectroscopic optical coherence tomography

      Intravascular optical coherence tomography (IV-OCT) is a high-resolution imaging method used to visualize the internal structures of walls of coronary arteries in vivo . However, accurate characterization of atherosclerotic plaques with gray-scale IV-OCT images is often limited by various intrinsic artifacts. In this study, we present an algorithm for characterizing lipid-rich plaques with a spectroscopic OCT technique based on a Gaussian center of mass (GCOM) metric. The GCOM metric, which reflects the absorbance properties of lipids, was validated using a lipid phantom. In addition, the proposed characterization method was successfully demonstrated in vivo using an atherosclerotic rabbit model and was found ...

      Read Full Article
    21. Intracoronary dual-modal optical coherence tomography-near-infrared fluorescence structural–molecular imaging with a clinical dose of indocyanine green for the assessment of high-risk plaques and stent-associated inflammation in a beating coronary artery

      Intracoronary dual-modal optical coherence tomography-near-infrared fluorescence structural–molecular imaging with a clinical dose of indocyanine green for the assessment of high-risk plaques and stent-associated inflammation in a beating coronary artery

      Aims Inflammation plays essential role in development of plaque disruption and coronary stent-associated complications. This study aimed to examine whether intracoronary dual-modal optical coherence tomography (OCT)-near-infrared fluorescence (NIRF) structural–molecular imaging with indocyanine green (ICG) can estimate inflammation in swine coronary artery. Methods and results After administration of clinically approved NIRF-enhancing ICG (2.0 mg/kg) or saline, rapid coronary imaging (20 mm/s pullback speed) using a fully integrated OCT-NIRF catheter was safely performed in 12 atheromatous Yucatan minipigs and in 7 drug-eluting stent (DES)-implanted Yorkshire pigs. Stronger NIRF activity was identified in OCT-proven high-risk plaque compared ...

      Read Full Article
    22. GPU-Accelerated Framework for Intracoronary Optical Coherence Tomography Imaging at the Push of a Button

      GPU-Accelerated Framework for Intracoronary Optical Coherence Tomography Imaging at the Push of a Button

      Frequency domain optical coherence tomography (FD-OCT) has become one of the important clinical tools for intracoronary imaging to diagnose and monitor coronary artery disease, which has been one of the leading causes of death. To help more accurate diagnosis and monitoring of the disease, many researchers have recently worked on visualization of various coronary microscopic features including stent struts by constructing three-dimensional (3D) volumetric rendering from series of cross-sectional intracoronary FD-OCT images. In this paper, we present the first, to our knowledge, "push-of-a-button" graphics processing unit (GPU)-accelerated framework for intracoronary OCT imaging. Our framework visualizes 3D microstructures of the ...

      Read Full Article
    23. Multi-functional angiographic OFDI using frequency-multiplexed dual-beam illumination

      Multi-functional angiographic OFDI using frequency-multiplexed dual-beam illumination

      Detection of blood flow inside the tissue sample can be achieved by measuring the local change of complex signal over time in angiographic optical coherence tomography (OCT). In conventional angiographic OCT, the transverse displacement of the imaging beam during the time interval between a pair of OCT signal measurements must be significantly reduced to minimize the noise due to the beam scanning-induced phase decorrelation at the expense of the imaging speed. Recent introduction of dual-beam scan method either using polarization encoding or two identical imaging systems in spectral-domain (SD) OCT scheme shows potential for high-sensitivity vasculature imaging without suffering from ...

      Read Full Article
    24. All-fiber wavelength swept ring laser based on Fabry-Perot filter for optical frequency domain imaging

      All-fiber wavelength swept ring laser based on  Fabry-Perot filter for optical frequency domain  imaging

      Innovations in laser engineering have yielded several novel configurations for high repetition rate, broad sweep range, and long coherence length wavelength swept lasers. Although these lasers have enabled high performance frequency-domain optical coherence tomography, they are typically complicated and costly and many require access to proprietary materials or devices. Here, we demonstrate a simplified ring resonator configuration that is straightforward to construct from readily available materials at a low total cost. It was enabled by an insight regarding the significance of isolation against bidirectional operation and by configuring the sweep range of the intracavity filter to exceed its free spectral ...

      Read Full Article
    1-24 of 36 1 2 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (30 articles) Korea Advanced Institute of Science and Technology
    2. (17 articles) Harvard University
    3. (17 articles) Massachusetts General Hospital
    4. (8 articles) Korea University
    5. (7 articles) Hanyang University
    6. (3 articles) Massachusetts Institute of Technology
    7. (2 articles) Samsung
    8. (2 articles) FDA
    9. (2 articles) Seoul National University
    10. (2 articles) Heidelberg Engineering
    11. (1 articles) Kyung Hee University
    12. (1 articles) Jichi Medical University
    13. (1 articles) Stanford University
    14. (1 articles) University of Florence
    15. (1 articles) Centre Hospitalier Intercommunal de Créteil
    16. (1 articles) University of Montreal
    17. (1 articles) Hanyang University
    18. (1 articles) University of Toronto
    19. (1 articles) Carl Zeiss Meditec
  3. Popular Articles

  4. Picture Gallery

    Performance of reduced bit-depth acquisition for optical frequency domain imaging Progress in Intracoronary Optical Coherence Tomography >400 kHz repetition rate wavelength-swept laser and application to high-speed optical frequency domain imaging Comprehensive esophageal microscopy by using optical frequency–domain imaging (with video) Complex wavefront shaping for optimal depth-selective focusing in optical coherence tomography Feature Of The Week 3/3/13: Complex wavefront shaping for optimal depth-selective focusing in optical coherence tomography Artifacts in polarization-sensitive optical coherence tomography caused by polarization mode dispersion Fully Integrated High-Speed Intravascular OCT/NIRF Structural/Molecular Imaging In Vivo Using a Clinically Available Near-Infrared Fluorescence–Emitting Indocyanine Green to Detect Inflamed Lipid-Rich Atheromata in Coronary-Sized Vessels Feature Of The Week 8/31/14: Fully Integrated High-speed Intravascular OCT/NIRF Structural/Molecular Imaging In Vivo using a Clinically-available NIRF Emitting Indocyanine Green to Detect Inflamed Lipid-rich Atheromata in Coronary-sized Vessels All-fiber wavelength swept ring laser based on  Fabry-Perot filter for optical frequency domain  imaging The truth about invisible posterior vitreous structures The Influence of Eyelid Position and Environmental Conditions on the Corneal Changes in Early Postmortem Interval: A Prospective, Multicentric OCT Study