1. Articles from Woo June Choi

    1-24 of 39 1 2 »
    1. 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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    2. 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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    3. 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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    4. Optical coherence tomography imaging of cranial meninges post brain injury in vivo

      Optical coherence tomography imaging of cranial meninges post brain injury in vivo

      We report a new application of optical coherence tomography (OCT) to investigate the cranial meninges in an animal model of brain injury in vivo. The injury is induced in a mouse due to skull thinning, in which the repeated and excessive drilling exerts mechanical stress on the mouse brain through the skull, resulting in acute and mild brain injury. Transcranial OCT imaging reveals an interesting virtual space between the cranial meningeal layers post skull thinning, which is gradually closed within hours. The finding suggests a promise of OCT as an effective tool to monitor the mechanical trauma in the small ...

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    5. Cerebral capillary velocimetry based on temporal OCT speckle contrast

      Cerebral capillary velocimetry based on temporal OCT speckle contrast

      We propose a new optical coherence tomography (OCT) based method to measure red blood cell (RBC) velocities of single capillaries in the cortex of rodent brain. This OCT capillary velocimetry exploits quantitative laser speckle contrast analysis to estimate speckle decorrelation rate from the measured temporal OCT speckle signals, which is related to microcirculatory flow velocity. We hypothesize that OCT signal due to sub-surface capillary flow can be treated as the speckle signal in the single scattering regime and thus its time scale of speckle fluctuations can be subjected to single scattering laser speckle contrast analysis to derive characteristic decorrelation time ...

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    6. Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo

      Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo

      Purpose : To perform an analysis of optical coherence tomography (OCT) abnormalities in patients with MEWDS, during the acute and recovery stages, using enhanced depth imaging-OCT (EDI-OCT). Methods : A retrospective case series of five patients with MEWDS was included. EDI-OCT imaging was evaluated to detect retinal and choroidal features. Results : In the acute phase, focal impairment of the ellipsoid zone and external limiting membrane, hyperreflective dots in the inner choroid, and full-thickness increase of the choroidal profile were observed in the affected eye; disappearance of these findings and restoration of the choroidal thickness ( p = 0.046) was appreciated in the recovery ...

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    7. Tail artifact removal in OCT angiography images of rodent cortex

      Tail artifact removal in OCT angiography images of rodent cortex

      Optical coherence tomography angiography (OCTA) is a surging non-invasive, label-free, in vivo volumetric imaging method, currently being translated to clinical ophthalmology and becoming popular in neuroscience. Despite its attractiveness, there is an inherent issue of using OCT angiograms for quantitative cerebrovascular studies: The dynamic scattering of moving erythrocytes within pial vasculature creates tail-like artifacts that shadow the capillary vessels in the deeper layers of cortex. This false flow effect is relatively benign for qualitative visualization purposes, but it might have a significant impact on quantitative interpretation of angiographic results. In this work, we propose a simple image processing method to ...

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    8. Quantitative Assessment of Anterior Segment Inflammation in a Rat Model of Uveitis Using Spectral-Domain Optical Coherence Tomography

      Quantitative Assessment of Anterior Segment Inflammation in a Rat Model of Uveitis Using Spectral-Domain Optical Coherence Tomography

      Purpose : To develop anterior segment spectral-domain optical coherence tomography (SD-OCT) and quantitative image analysis for use in experimental uveitis in rats. Methods : Acute anterior uveitis was generated in Lewis rats. A spectral domain anterior segment OCT system was used to image the anterior chamber (AC) and ciliary body at baseline and during peak inflammation 2 days later. Customized MatLab image analysis algorithms were developed to segment the AC, count AC cells, calculate central corneal thickness (CCT), segment the ciliary body and zonules, and quantify the level of ciliary body inflammation with the ciliary body index (CBI). Images obtained at baseline ...

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    9. Automated segmentation and enhancement of optical coherence tomography-acquired images of rodent brain

      Automated segmentation and enhancement of optical coherence tomography-acquired images of rodent brain

      Background Optical coherence tomography (OCT) is a non-invasive optical imaging method that has proven useful in various fields such as ophthalmology, dermatology and neuroscience. In ophthalmology, significant progress has been made in retinal layer segmentation and enhancement of OCT images. There are also segmentation algorithms to separate epidermal and dermal layers in OCT-acquired images of human skin. New Method We describe simple image processing methods that allow automatic segmentation and enhancement of OCT images of rodent brain. Results We demonstrate the effectiveness of the proposed methods for OCT-based microangiography (OMAG) and tissue injury mapping (TIM) of mouse cerebral cortex. The ...

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    10. Wide-field optical coherence tomography angiography enabled by two repeated measurements of B-scans

      Wide-field optical coherence tomography angiography enabled by two repeated measurements of B-scans

      Optical coherence tomography angiography (OCTA) has increasingly become clinically important, particularly in ophthalmology. However, the field of view (FOV) for current OCTA imaging is severely limited due to A-scan rates that can be afforded by current clinical systems and, more importantly, the requirement of a repeated scanning protocol. This Letter evaluates the possibility of using only two repeated B-scans for OCTA for the purpose of an increased FOV. The effect of repeated numbers on the OCTA result is discussed through experiments on an animal model in vivo and evaluated using quantitative metrics for image quality. Demonstrated through in vivo imaging ...

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    11. Automated detection of inflammatory cells in whole anterior chamber of a uveitis mouse from swept-source optical coherence tomography images

      Automated detection of inflammatory cells in whole anterior chamber of a uveitis mouse from swept-source optical coherence tomography images

      Cell grading in a rodent anterior chamber is essential for anterior inflammation evaluation in preclinical vision research. This paper describes a computerized method for detection and counting of the anterior chamber cells from swept-source optical coherence tomography (SS-OCT) images of a experimental rodent model of uveitis. The volumetric anterior segment OCT data is obtained from 100 kHz SS-OCT imaging of mouse eye in vivo. For the OCT cross-sections, each OCT structural image is de-speckled and binarized. After removal of cornea, iris, and crystalline lens structures connected to the binary image border, an area thresholding is then employed for each labeled ...

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    12. Swept-source optical coherence tomography powered by a 1.3-μm vertical cavity surface emitting laser enables 2.3-mm-deep brain imaging in mice in vivo

      Swept-source optical coherence tomography powered by a 1.3-μm vertical cavity surface emitting laser enables 2.3-mm-deep brain imaging in mice in vivo

      We report noninvasive, in vivo optical imaging deep within a mouse brain by swept-source optical coherence tomography (SS-OCT), enabled by a 1.3 - μ m vertical cavity surface emitting laser (VCSEL). VCSEL SS-OCT offers a constant signal sensitivity of 105 dB throughout an entire depth of 4.25 mm in air, ensuring an extended usable imaging depth range of more than 2 mm in turbid biological tissue. Using this approach, we show deep brain imaging in mice with an open-skull cranial window preparation, revealing intact mouse brain anatomy from the superficial cerebral cortex to the deep hippocampus. VCSEL SS-OCT would be ...

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    13. Feature Of The Week 03/29/15: University of Washington Demonstrates In vivo Microvascular Imaging of Human Oral and Nasal Cavities using SS-OCT

      Feature Of The Week 03/29/15: University of Washington Demonstrates In vivo Microvascular Imaging of Human Oral and Nasal Cavities using SS-OCT

      Over decades, optical coherence tomography (OCT) has proven useful in the diagnosis of cavity disorders through in vivo feasibility or clinical studies in human. OCT studies have evaluated changes in cavity tissue morphology and optical properties of backscattered OCT signals from cavity tissue layers for the identification of abnormalities. Notwithstanding, there has been limited discussion regarding the assessment of microvasculature in human cavity tissues. The microcirculation within cavity tissues would be an invaluable indicator for assessing cavity disorders due to vascular malformation associated with disease progression. In this work, we report three-dimensional (3D) imaging of microcirculation within human cavity tissues ...

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    14. Characterization of rat model of acute anterior uveitis using optical coherence tomography angiography

      Characterization of rat model of acute anterior uveitis using optical coherence tomography angiography

      Uveitis, or ocular inflammation, is a cause of severe visual impairment. Rodent models of uveitis are powerful tools used to investigate the pathological mechanisms of ocular inflammation and to study the efficacy of new therapies prior to human testing. In this paper, we report the utility of spectral-domain optical coherence tomography (SD-OCT) angiography in characterizing the inflammatory changes induced in the anterior segment of a rat model of uveitis. Acute anterior uveitis (AAU) was induced in two rats by intravitreal injection of a killed mycobacterial extract. One of them received a concurrent periocular injection of steroids to model a treatment ...

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    15. In vivo microvascular imaging of human oral and nasal cavities using swept-source optical coherence tomography with a single forward/side viewing probe

      In vivo microvascular imaging of human oral and nasal cavities using swept-source optical coherence tomography with a single forward/side viewing probe

      We report three-dimensional (3D) imaging of microcirculation within human cavity tissues in vivo using a high-speed swept-source optical coherence tomography (SS-OCT) at 1.3 μm with a modified probe interface. Volumetric structural OCT images of the inner tissues of oral and nasal cavities are acquired with a field of view of 2 mm x 2 mm. Two types of disposable and detachable probe attachments are devised and applied to the port of the imaging probe of OCT system, enabling forward and side imaging scans for selective and easy access to specific cavity tissue sites. Blood perfusion is mapped with OCT-based ...

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    16. High resolution imaging of acne lesion development and scarring in human facial skin using OCT-based microangiography

      High resolution imaging of acne lesion development and scarring in human facial skin using OCT-based microangiography

      Background and Objective Acne is a common skin disease that often leads to scarring. Collagen and other tissue damage from the inflammation of acne give rise to permanent skin texture and microvascular changes. In this study, we demonstrate the capabilities of optical coherence tomography-based microangiography in detecting high-resolution, three-dimensional structural, and microvascular features of in vivo human facial skin during acne lesion initiation and scar development. Materials and Methods A real time swept source optical coherence tomography system is used in this study to acquire volumetric images of human skin. The system operates on a central wavelength of 1,310 ...

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    17. Optical coherence tomography based microangiography for quantitative monitoring of structural and vascular changes in a rat model of acute uveitis in vivo: a preliminary study

      Optical coherence tomography based microangiography for quantitative monitoring of structural and vascular changes in a rat model of acute uveitis in vivo: a preliminary study

      Uveitis models in rodents are important in the investigation of pathogenesis in human uveitis and the development of appropriate therapeutic strategies for treatment. Quantitative monitoring of ocular inflammation in small animal models provides an objective metric to assess uveitis progression and/or therapeutic effects. We present a new application of optical coherence tomography (OCT) and OCT-based microangiography (OMAG) to a rat model of acute anterior uveitis induced by intravitreal injection of a killed mycobacterial extract. OCT/OMAG is used to provide noninvasive three-dimensional imaging of the anterior segment of the eyes prior to injection (baseline) and two days post-injection (peak ...

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    18. Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

      Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

      We demonstrate volumetric cutaneous microangiography of the human skin in vivo that utilises 1.3-μm high-speed sweptsource optical coherence tomography (SS-OCT). The swept source is based on a micro-electro-mechanical (MEMS)-tunable vertical cavity surface emission laser (VCSEL) that is advantageous in terms of long coherence length over 50 mm and 100 nm spectral bandwidth, which enables the visualisation of microstructures within a few mm from the skin surface. We show that the skin microvasculature can be delineated in 3D SS-OCT images using ultrahigh-sensitive optical microangiography (UHS-OMAG) with a correlation mapping mask, providing a contrast enhanced blood perfusion map with ...

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    19. Optical coherence tomography microangiography for monitoring the response of vascular perfusion to external pressure on human skin tissue

      Optical coherence tomography microangiography for monitoring the response of vascular perfusion to external pressure on human skin tissue

      Characterization of the relationship between external pressure and blood flow is important in the examination of pressure-induced disturbance in tissue microcirculation. Optical coherence tomography (OCT)-based microangiography is a promising imaging technique, capable of providing the noninvasive extraction of functional vessels within the skin tissue with capillary-scale resolution. Here, we present a feasibility study of OCT microangiography (OMAG) to evaluate changes in blood perfusion in response to externally applied pressure on human skin tissue in vivo . External force is loaded normal to the tissue surface at the nailfold region of a healthy human volunteer. An incremental force is applied step ...

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    20. In vivo OCT microangiography of rodent iris

      In vivo OCT microangiography of rodent iris

      We report on the functional optical coherence tomography (OCT) imaging of iris tissue morphology and microcirculation in living small animals. Anterior segments of healthy mouse and rat eyes are imaged with high-speed spectral domain OCT (SD-OCT) utilizing ultrahigh sensitive optical microangiography (UHS-OMAG) imaging protocol. 3D iris microvasculature is produced by the use of an algorithm that calculates absolute differences between the amplitudes of the OCT interframes. We demonstrate that the UHS-OMAG is capable of delineating iris microvascular beds in the mouse and rat with capillary-level resolution. Furthermore, the fast imaging speed enables dynamic imaging of iris micro-vascular response during drug-induced ...

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    21. Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Optical microangiography based on optical coherence tomography (OCT) is prone to noise that arises from a static tissue region. Here, we propose a method that can significantly reduce this noise. The method is developed based on an approach that uses the magnitude information of OCT signals to produce tissue microangiograms, especially suitable for the case where a swept-source OCT system is deployed. By combined use of two existing OCT microangiography methods—ultrahigh-sensitive optical microangiography (UHS-OMAG) and correlation mapping OCT (cmOCT)—the final tissue microangiogram is generated by masking UHS-OMAG image using the binary representation of cmOCT image. We find that ...

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    22. Analysis of cross-sectional image filters for evaluating nonaveraged optical microangiography images

      Analysis of cross-sectional image filters for evaluating nonaveraged optical microangiography images

      Optical microangiography (OMAG) is a method that enables the noninvasive extraction of blood vessels within biological tissues. OMAG B-frames are prone to noise; therefore, techniques such as B-frame averaging have been applied to reduce these effects. A drawback of this method is that the total acquisition time and amount of data collected are increased; hence, the data are susceptible to motion artifacts and decorrelation. In this paper we propose using an image filter on a nonaveraged OMAG B-frame to reduce its noise. Consequently, B-frames comparable to the averaged OMAG B-frame are obtained, while reducing the total acquisition and processing time ...

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    23. Refractive index measurements of multiple layers using numerical refocusing in FF-OCT

      Refractive index measurements of multiple layers using numerical refocusing in FF-OCT

      We propose and demonstrate the novel method of refractive index (RI) measurement for each layer of multilayered samples, which is based on numerical refocusing in full field optical coherence tomography (FF-OCT). The en-face FF-OCT image on an inner layer boundary of a multilayered sample is unintentionally blurred or defocused due to the RI of the sample itself, but can be numerically refocused. The refocusing is performed by numerically shifting the image sensor plane of the system, in general. However, by calculating the corresponding sample shift and then compared it with the actual sample shifting distance, we could extract the average ...

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    24. Single-camera polarization-sensitive full-field optical coherence tomography with polarization switch

      Single-camera polarization-sensitive full-field optical coherence tomography with polarization switch

      We present a single-channel detection-based polarization-sensitive full-field optical coherence tomography (PS-FF-OCT) for simultaneous acquisition of high-resolution OCT and linear retardance images. A linearly polarized sub-10-fs laser was used as a broadband light source for the OCT system. A bi-stable polarization switching device, composed of a ferroelectric liquid crystal cell and an analyzer, was employed to get the horizontal and the vertical polarization components of a full-field interference signal. The time-switched two perpendicular interference signals were sequentially recorded by a single charge-coupled device camera, then processed to extract en-face functional images of a biological sample. The rat tail tendon was imaged ...

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    1-24 of 39 1 2 »
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    1. (39 articles) Woo June Choi
    2. (24 articles) University of Washington
    3. (22 articles) Ruikang K. Wang
    4. (17 articles) Gwangju Institute of Science and Technology
    5. (16 articles) Byeong Ha Lee
    6. (5 articles) Seon Young Ryu
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    Full-field optical coherence microscopy for identifying live cancer cells by quantitative measurement of refractive index distribution Feasibility of Full-field Optical Coherence Microscopy in Ultra-structural Imaging of Human Colon Tissues Feature Of The Week 3/27/11: Feasibility of Full-Field Optical Coherence Tomography for Detection of Counterfeit Paper Money Characterization of wet pad surface in chemical mechanical polishing (CMP) process with full-field optical coherence tomography (FF-OCT) Feature Of The Week 03/29/15: University of Washington Demonstrates In vivo Microvascular Imaging of Human Oral and Nasal Cavities using SS-OCT Research Associate / Postdoctoral Fellow in Adaptive Optics and Optical Coherence Tomography at Indiana University Spectral interferogram prediction in high resolution dual- and multiple-band Fourier domain optical coherence tomography Process control and quality assurance in remote laser beam welding by optical coherence tomography Inline weld depth measurement for high brilliance laser beam sources using optical coherence tomography Multimodal endoscopy for colorectal cancer detection by optical coherence tomography and near-infrared fluorescence imaging Impact of optical coherence tomography on diagnostic decision-making by UK community optometrists: a clinical vignette study Scheimpflug Camera and Swept-Source Optical Coherence Tomography in Pachymetry Evaluation of Diabetic Patients