1. Articles from Myeong Jin Ju

    1-21 of 21
    1. Directional optical coherence tomography reveals melanin concentration-dependent scattering properties of retinal pigment epithelium

      Directional optical coherence tomography reveals melanin concentration-dependent scattering properties of retinal pigment epithelium

      Optical coherence tomography (OCT) is a powerful tool in ophthalmology that provides in vivo morphology of the retinal layers and their light scattering properties. The directional (angular) reflectivity of the retinal layers was investigated with focus on the scattering from retinal pigment epithelium (RPE). The directional scattering of the RPE was studied in three mice strains with three distinct melanin concentrations: albino (BALB/c), agouti (129S1/SvlmJ), and strongly pigmented (C57BL/6J). The backscattering signal strength was measured with a directional OCT system in which the pupil entry position of the narrow OCT beam can be varied across the dilated ...

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    2. Multi-scale and -contrast sensorless adaptive optics optical coherence tomography

      Multi-scale and -contrast sensorless adaptive optics optical coherence tomography

      Background: The roles of the retinal microvasculature and the retinal pigment epithelium (RPE) in maintaining the health and metabolic activity of the retina lend great clinical value to their high-resolution visualization. Methods: By integrating polarization diversity detection (PDD) into multi-scale and -contrast sensorless adaptive optics optical coherence tomography (MSC-SAO-OCT), we have developed a novel multi-contrast SAO OCT system for imaging pigment in the RPE as well as flow in the retinal capillaries using OCT angiography (OCTA). Aberration correction was performed based on the image quality using transmissive deformable optical elements. Results: MSC-SAO-OCTA imaging was performed at multiple fields-of-view (FOVs) with ...

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    3. Slope-based segmentation of articular cartilage using polarization-sensitive optical coherence tomography phase retardation image

      Slope-based segmentation of articular cartilage using polarization-sensitive optical coherence tomography phase retardation image

      A segmentation method based on phase retardation measurements from polarization-sensitive optical coherence tomography (PS-OCT) is developed to differentiate the structural zones of articular cartilage. The organization of collagen matrix in articular cartilage varies over the different structural zones, generating different tissue birefringence. Analyzing the slope of the accumulated phase retardation at different depths can detect the variation in tissue birefringence and be used to segment the structural zones. The method is validated on phantoms composed of layers of different materials. Articular cartilage samples from adult swine are segmented with the method. The characteristics in each segmented zone are also examined ...

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    4. Automated identification of cone photoreceptors in adaptive optics optical coherence tomography images using transfer learning

      Automated identification of cone photoreceptors in adaptive optics optical coherence tomography images using transfer learning

      Automated measurements of the human cone mosaic requires the identification of individual cone photoreceptors. The current gold standard, manual labeling, is a tedious process and can not be done in a clinically useful timeframe. As such, we present an automated algorithm for identifying cone photoreceptors in adaptive optics optical coherence tomography (AO-OCT) images. Our approach fine-tunes a pre-trained convolutional neural network originally trained on AO scanning laser ophthalmoscope (AO-SLO) images, to work on previously unseen data from a different imaging modality. On average, the automated method correctly identified 94% of manually labeled cones when compared to manual raters, from twenty ...

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    5. Visible light sensorless adaptive optics for retinal structure and fluorescence imaging

      Visible light sensorless adaptive optics for retinal structure and fluorescence imaging

      Optical coherence tomography (OCT) has emerged as a powerful imaging instrument and technology in biomedicine. OCT imaging is predominantly performed using wavelengths in the near infrared; however, visible light (VIS) has been recently employed in OCT systems with encouraging results for high-resolution retinal imaging. Using a broadband supercontinuum VIS source, we present a sensorless adaptive optics (SAO) multimodal imaging system driven by VIS-OCT for volumetric retinal structural imaging, followed by the acquisition of fluorescence emission. The coherence-gated, depth-resolved VIS-OCT images used for image-guided SAO aberration correction enable high-resolution structural and fluorescence imaging.

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    6. Effective bidirectional scanning pattern for optical coherence tomography angiography

      Effective bidirectional scanning pattern for optical coherence tomography angiography

      We demonstrate the utility of a novel scanning method for optical coherence tomography angiography (OCTA). Although raster scanning is commonly used for OCTA imaging, a bidirectional approach would lessen the distortion caused by galvanometer-based scanners as sources continue to increase sweep rates. As shown, a unidirectional raster scan approach has a lower effective scanning time than bidirectional approaches; however, a strictly bidirectional approach causes contrast variation along the B-scan direction due to the non-uniform time interval between B-scans. Therefore, a stepped bidirectional approach is introduced and successfully applied to retinal imaging in normal controls and in a pathological subject with ...

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    7. Investigation of the effect of directional (off-axis) illumination on the reflectivity of retina layers in mice using swept-source optical coherence tomography

      Investigation of the effect of directional (off-axis) illumination on the reflectivity of retina layers in mice using swept-source optical coherence tomography

      Changes in visibility of the Henle fiber layer and photoreceptor bands of the human retina with illumination directionality have been reported in OCT clinical imaging. These are a direct consequence of the changes in back scattering due to fibrous tissue orientation and to waveguiding properties of the photoreceptors respectively. Here we report the preliminary results of a study on the effects of retinal images acquired with OCT of illumination directionality in the mouse retina. The quantitative assessment of the reflectivity of retinal layers of a BALB/c and WT pigmented mice was performed in-vivo using a swept-source optical coherence tomography ...

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    8. Multiscale sensorless adaptive optics OCT angiography system for in vivo human retinal imaging

      Multiscale sensorless adaptive optics OCT angiography system for in vivo human retinal imaging

      We present a multiscale sensorless adaptive optics (SAO) OCT system capable of imaging retinal structure and vasculature with various fields-of-view (FOV) and resolutions. Using a single deformable mirror and exploiting the polarization properties of light, the SAO-OCT-A was implemented in a compact and easy to operate system. With the ability to adjust the beam diameter at the pupil, retinal imaging was demonstrated at two different numerical apertures with the same system. The general morphological structure and retinal vasculature could be observed with a few tens of micrometer-scale lateral resolution with conventional OCT and OCT-A scanning protocols with a 1.7-mm-diameter ...

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    9. Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

      Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

      Polarization-sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are two imaging modalities with different resolutions, field-of-views (FOV), and contrasts, while they both have the capability of imaging collagen fibers in biological tissues. PS-OCT can measure the tissue birefringence which is induced by highly organized fibers while SHG can image the collagen fiber organization with high resolution. Articular cartilage, with abundant structural collagen fibers, is a suitable sample to study the correlation between PS-OCT and SHG microscopy. Qualitative conjecture has been made that the phase retardation measured by PS-OCT is affected by the relationship between the collagen fiber ...

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    10. Lens-based wavefront sensorless adaptive optics swept source OCT

      Lens-based wavefront sensorless adaptive optics swept source OCT

      Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high ...

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    11. Retinal optical coherence tomography at 1  μm with dynamic focus control and axial motion tracking

      Retinal optical coherence tomography at 1  μm with dynamic focus control and axial motion tracking

      High-resolution optical coherence tomography (OCT) retinal imaging is important to noninvasively visualize the various retinal structures to aid in better understanding of the pathogenesis of vision-robbing diseases. However, conventional OCT systems have a trade-off between lateral resolution and depth-of-focus. In this report, we present the development of a focus-stacking OCT system with automatic focus optimization for high-resolution, extended-focal-range clinical retinal imaging by incorporating a variable-focus liquid lens into the sample arm optics. Retinal layer tracking and selection was performed using a graphics processing unit accelerated processing platform for focus optimization, providing real-time layer-specific en face visualization. After optimization, multiple volumes ...

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    12. Usage of polarization-sensitive optical coherence tomography for investigation of collagen cross-linking

      Usage of polarization-sensitive optical coherence tomography for investigation of collagen cross-linking

      To investigate morphological alternation in corneal stroma induced by collagen cross-linking (CXL) treatment, polarization-sensitive optical coherence tomography (PS-OCT) capable of providing scattering, phase retardation, and degree of polarization uniformity (DOPU) images were employed on fresh bovine cornea. Significant corneal thickness reduction was observed after the CXL procedure, and its variation was quantitatively analyzed. From the scattering contrast, a hyperscattering region was observed in the anterior of the cornea immediately after the CXL procedure and its range increased with time. Within the scattering region, a slow increase was observed in the phase retardation image, and a discriminable characteristic was found in ...

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    13. Simultaneous Investigation of Vascular and Retinal Pigment Epithelial Pathologies of Exudative Macular Diseases by Multi-Functional Optical Coherence Tomography

      Simultaneous Investigation of Vascular and Retinal Pigment Epithelial Pathologies of Exudative Macular Diseases by Multi-Functional Optical Coherence Tomography

      Purpose: To investigate exudative macular disease, multi-functional optical coherence tomography (MF-OCT) using a 1-μm probe band was developed. The clinical utility of MF-OCT was examined in a descriptive case series. Methods: Ten eyes of nine subjects with exudative macular disease, including one eye with age-related macular degeneration (AMD), one eye with idiopathic neovascular maculopathy, and eight eyes with polypoidal choroidal vasculopathy (PCV), were investigated. Areas of 6 × 6 mm 2 around the pathologic region were scanned with 512 × 1024 depth scans in 6.6 seconds. Structural OCT, Doppler optical coherence angiography (OCA) and cumulative phase retardation images were obtained ...

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    14. Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography

      Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography

      In this study, polarization-sensitive optical coherence tomography (PS-OCT) capable of providing polarization contrasts such as phase retardation and degree of polarization uniformity (DOPU) was used for visualizing human meibomian glands (MGs) and investigating morphological characteristics of them. Especially, with the help of the DOPU contrast, MGs were exclusively extracted from the volumetric OCT image. In vivo PS-OCT measurements were performed on the upper eyelids of different age groups. From these measurements, different age-dependent aspects of the MG structure were also observed. Based on these observations, it can be inferred that the PS-OCT system has the potential for clinical diagnosis and ...

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    15. Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

      Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

      An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced ...

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    16. Multimodal optical imaging with multiphoton microscopy and optical coherence tomography

      Multimodal optical imaging with multiphoton microscopy and optical coherence tomography

      Two types of combined multiphoton microscopy and optical coherence tomography (MPM/OCT) are compared for multimodal optical imaging. Single-scale multiphoton microscopy and optical coherence microscopy (MPM/OCM) is shown to acquire multiple contrasts from MPM and OCT simultaneously. Multi-scale MPM/OCT is shown to provide multiple field-of-views (FOVs), where OCT provides tissue level imaging and MPM provides cellular level imaging. In both types, the MPM includes two channels which are two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Representative images using each system are demonstrated on biological specimens. A detailed comparison of the two types of MPM/OCT shows ...

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    17. High-penetration swept source Doppler optical coherence angiography by fully numerical phase stabilization

      High-penetration swept source Doppler optical coherence angiography by fully numerical phase stabilization
      A high-penetration swept-source optical coherence tomography (HP-SS-OCT) system based on a 1-μm short cavity laser is developed. Doppler OCT processing is applied, along with a custom-made numerical phase stabilization algorithm; this process does not require additional calibration hardware. Thus, our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. The bidirectional blood flow and vasculature in the deep choroid was successfully imaged via two Doppler modes that use different time intervals for Doppler processing. En face projection image of squared power of Doppler shift is compared to ICGA, and the utility of our method ...
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    18. Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy

      Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy
      , , , , , , , We present an integrated optical system that consists of optical coherence tomography (OCT) and laser-induced fluorescence (LIF) spectroscopy for multimodal analysis of pearls and pearl treatments. The OCT source and the LIF excitation beams were aligned together to illuminate the same spot of a ... [Opt. Express 19, 6420-6432 (2011)]
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    19. 2X2 Photonic Crystal Fiber Splitter For 800 Nm Spectral Domain Optical Coherence Tomography

      2X2 Photonic Crystal Fiber Splitter For 800 Nm Spectral Domain Optical Coherence Tomography

      We report the fabrication and performance of the 2x2 photonic crystal fiber (PCF) splitter that was designed as a single mode splitter at the 800 nm optical band and used as the beam splitter for a spectral domain optical coherence tomography system. The PCF splitter has been made by coupling PCFs to a planar lightwave circuit (PLC) splitter chip. The PLC splitter chip was fabricated to have a single mode property at the 800 nm wavelength band and the PCFs were securely connected to the PLC chip through PCF block arrays having lithographically fabricated V grooves. The core size of ...

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    20. Evaluating and identifying pearls and their nuclei by using optical coherence tomography

      Evaluating and identifying pearls and their nuclei by using optical coherence tomography
      Optical coherence tomography (OCT) has been utilized to evaluate pearls including their nuclei noninvasively. By visualizing the internal structure of a pearl, we could measure the thickness of its nacre layer, observe the fine sub-structure of the nacre, and inspect the nucleus through the nacre. The system also allowed us to classify pearls into beaded- and non-beaded ones; usually, the saltwater ones have nuclei even though there are beaded freshwater pears and non-beaded saltwater pearls. Any cracks, crevices, or blemishes not only in the nacre but in the nucleus of a pearl could be clearly visualized. The OCT system was ...
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    21. Combined swept-source optical coherence tomography and fluorescence spectroscopy system

      Combined swept-source optical coherence tomography and fluorescence spectroscopy system

      We report a combined swept source optical coherence tomography (SSOCT) and fluorescence spectroscopy (FS) system for multimodal measurements of biochemical information and internal structures with fast imaging speed. The FS probe composed of a double clad fiber (DCF) coupler is adopted into the single mode fiber based SSOCT system. Here, the DCF coupler acts as a FS system as well as a multifunctional probe for the SSOCT-FS system. The performances of the single-unit SSOCT-FS system is confirmed by monitoring the fluorescence signal from photosensitizer in cancerous region of in-vivo rat and by imaging the internal structures of same region with ...

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    1-21 of 21
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  2. Topics in the News

    1. (21 articles) Myeong Jin Ju
    2. (11 articles) Simon Fraser University
    3. (9 articles) University of British Columbia
    4. (8 articles) Marinko V. Sarunic
    5. (7 articles) Yifan Jian
    6. (6 articles) University of Tsukuba
    7. (6 articles) Gwangju Institute of Science and Technology
    8. (6 articles) Yoshiaki Yasuno
    9. (6 articles) Byeong Ha Lee
    10. (4 articles) Shuichi Makita
    11. (2 articles) Columbia University
    12. (2 articles) Christine P. Hendon
    13. (2 articles) Canon Medical Systems
    14. (1 articles) University of Houston
    15. (1 articles) Kyoto University Graduate School of Medicine
    16. (1 articles) Dmitry A. Terpelov
    17. (1 articles) David D. Sampson
    18. (1 articles) Eric A. Swanson
    19. (1 articles) Akitaka Tsujikawa
    20. (1 articles) Kirill V. Larin
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    Combined swept-source optical coherence tomography and fluorescence spectroscopy system Evaluating and identifying pearls and their nuclei by using optical coherence tomography Multimodal analysis of pearls and pearl treatments by using optical coherence tomography and fluorescence spectroscopy 2X2 Photonic Crystal Fiber Splitter For 800 Nm Spectral Domain Optical Coherence Tomography High-penetration swept source Doppler optical coherence angiography by fully numerical phase stabilization Multimodal optical imaging with multiphoton microscopy and optical coherence tomography Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography Simultaneous Investigation of Vascular and Retinal Pigment Epithelial Pathologies of Exudative Macular Diseases by Multi-Functional Optical Coherence Tomography Retinal optical coherence tomography at 1  μm with dynamic focus control and axial motion tracking Miniaturizing medical imaging, sensing technology On-chip tunable photonic delay line