1. Articles from Ki Hean Kim

    1-23 of 23
    1. Characterization of early-stage cutaneous radiation injury by using optical coherence tomography angiography

      Characterization of early-stage cutaneous radiation injury by using optical coherence tomography angiography

      Cutaneous radiation injury (CRI) is a skin injury caused by exposure to high dose ionizing radiation (IR). Diagnosis and treatment of CRI is difficult due to its initial clinically latent period and the following inflammatory bursts. Early detection of CRI before clinical symptoms will be helpful for effective treatment, and various optical methods have been applied with limitations. Here we show that optical coherence tomography angiography (OCTA) could detect changes in the skin during the latent period in CRI mouse models non-invasively. CRI was induced on the mouse hindlimb with exposure to various IR doses and the injured skin regions ...

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      Mentions: Ki Hean Kim
    2. Skin Imaging using Ultrasound Imaging, Optical Coherence Tomography, Confocal Microscopy, and Two-Photon Microscopy in Cutaneous Oncology

      Skin Imaging using Ultrasound Imaging, Optical Coherence Tomography, Confocal Microscopy, and Two-Photon Microscopy in Cutaneous Oncology

      With the recognition of dermoscopy as a new medical technology and its available fee assessment in Korea comes an increased interest in imaging-based dermatological diagnosis. For the dermatologist, who treats benign tumors and malignant skin cancers, imaging-based evaluations can assist with determining the surgical method and future follow-up plans. The identification of the tumor’s location and the existence of blood vessels can guide safe treatment and enable the use of minimal incisions. The recent development of high-resolution microscopy based on laser reflection has enabled observation of the skin at the cellular level. Despite the limitation of a shallow imaging ...

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    3. Dermoscopy guided dark-field multi-functional optical coherence tomography

      Dermoscopy guided dark-field multi-functional optical coherence tomography

      Dermoscopy is a skin surface microscopic technique allowing specular reflection free observation of the skin, and has been used to examine pigmented skin lesions. However, dermoscopy has limitations in providing depth information due to lack of 3D resolution. In order to overcome the limitations, we developed dermoscopy guided multi-functional optical coherence tomography (MF-OCT) providing both high-contrast superficial information and depth-resolved structural, birefringent, and vascular information of the skin simultaneously. Dermoscopy and MF-OCT were combined by using a dichroic mirror, and dark-field configuration was adapted for MF-OCT to reduce specular reflection. After characterization, dermoscopy guided MF-OCT was applied to several human ...

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    4. Miniaturization of plastic lens by injection molding for disposable endoscopie optical coherence tomography system

      Miniaturization of plastic lens by injection molding for disposable endoscopie optical coherence tomography system

      Minimally invasive robotic surgery required disposable endoscopie optical coherence tomography (OCT) for high-resolution deep tissue imaging and cross-contamination prevention. Here, we developed a miniaturized plastic lens by injection molding for developing a disposable endoscopie optical coherence tomography system for the first time. Injection molding provided low-cost and high-production rate to produce a disposable plastic lens and enabled the miniaturization of plastic lens. Transmittance and curvature of the plastic lens was measured. The plastic lens was integrated with an endoscopie OCT system, and the images of human-skin and microspheres embedded in agarose gel were captured. We are currently trying to integrate ...

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      Mentions: Ki Hean Kim
    5. Visualization of prostatic nerves by polarization-sensitive optical coherence tomography

      Visualization of prostatic nerves by polarization-sensitive optical coherence tomography

      Preservation of prostatic nerves is critical to recovery of a man’s sexual potency after radical prostatectomy. A real-time imaging method of prostatic nerves will be helpful for nerve-sparing radical prostatectomy (NSRP). Polarization-sensitive optical coherence tomography (PS-OCT), which provides both structural and birefringent information of tissue, was applied for detection of prostatic nerves in both rat and human prostate specimens, ex vivo. PS-OCT imaging of rat prostate specimens visualized highly scattering and birefringent fibrous structures superficially, and these birefringent structures were confirmed to be nerves by histology or multiphoton microscopy (MPM). PS-OCT could easily distinguish these birefringent structures from surrounding ...

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      Mentions: Ki Hean Kim
    6. In vivo visualization of skin inflammation by optical coherence tomography and two-photon microscopy

      In vivo visualization of skin inflammation by optical coherence tomography and two-photon microscopy

      Inflammation is a non-specific immune response to injury intended to protect biological tissue from harmful stimuli such as pathogens, irritants, and damaged cells. In vivo optical tissue imaging has been used to provide spatial and dynamic characteristics of inflammation within the tissue. In this paper, we report in vivo visualization of inflammation in the skin at both cellular and physiological levels by using a combination of label-free two-photon microscopy (TPM) and optical coherence tomography (OCT). Skin inflammation was induced by topically applying lipopolysaccharide (LPS) on the mouse ear. Temporal OCT imaging visualized tissue swelling, vasodilation, and increased capillary density 30 ...

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      Mentions: Ki Hean Kim
    7. Correlation between polarization sensitive optical coherence tomography and second harmonic generation microscopy in skin

      Correlation between polarization sensitive optical coherence tomography and second harmonic generation microscopy in skin

      Both polarization sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are 3D optical imaging methods providing information related to collagen in the skin. PS-OCT provides birefringence information which is due to the collagen composition of the skin. SHG microscopy visualizes collagen fibers in the skin based on their SHG property. These two modalities have been applied to the same skin pathologies associated with collagen changes, but their relationship has not been examined. In this study, we tried to find the relationship by imaging the same skin samples with both modalities. Various parts of the normal rat skin ...

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      Mentions: Ki Hean Kim
    8. Dark-field polarization-sensitive optical coherence tomography

      Dark-field polarization-sensitive optical coherence tomography

      Polarization-sensitive optical coherence tomography (PS-OCT) is a functional OCT providing both structural and birefringent information of the sample, and it has been applied to the studies of various organs having polarization properties. Fiber-based PS-OCT is sensitive to specular reflection from the sample surface, because signal saturation due to the strong specular reflection can make the polarization measurement difficult. We developed a dark-field PS-OCT which can avoid the specular reflection problem. Dark-field PS-OCT was implemented by adapting a hybrid method of Bessel-beam illumination and Gaussian-beam detection, and a PS-OCT method based on passive delay unit (PDU). The new system was characterized ...

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    9. In vivo wide-field reflectance/fluorescence imaging and polarization-sensitive optical coherence tomography of human oral cavity with a forward-viewing probe

      In vivo wide-field reflectance/fluorescence imaging and polarization-sensitive optical coherence tomography of human oral cavity with a forward-viewing probe

      We report multimodal imaging of human oral cavity in vivo based on simultaneous wide-field reflectance/fluorescence imaging and polarization-sensitive optical coherence tomography (PS-OCT) with a forward-viewing imaging probe. Wide-field reflectance/fluorescence imaging and PS-OCT were to provide both morphological and fluorescence information on the surface, and structural and birefringent information below the surface respectively. The forward-viewing probe was designed to access the oral cavity through the mouth with dimensions of approximately 10 mm in diameter and 180 mm in length. The probe had field of view (FOV) of approximately 5.5 mm in diameter, and adjustable depth of field (DOF ...

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    10. Gradient index lens based combined two-photon microscopy and optical coherence tomography

      Gradient index lens based combined two-photon microscopy and optical coherence tomography

      We report a miniaturized probe-based combined two-photon microscopy (TPM) and optical coherence tomography (OCT) system. This system is to study the colorectal cancer in mouse models by visualizing both cellular and structural information of the colon in 3D with TPM and OCT respectively. The probe consisted of gradient index (GRIN) lenses and a 90° reflecting prism at its distal end for side-viewing, and it was added onto an objective lens-based TPM and OCT system. The probe was 2.2 mm in diameter and 60 mm in length. TPM imaging was performed by raster scanning of the excitation focus at the ...

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    11. Detection of pH-induced aggregation of "smart" gold nanoparticles with photothermal optical coherence tomography

      Detection of pH-induced aggregation of "smart" gold nanoparticles with photothermal optical coherence tomography

      We report the feasibility of a novel contrast agent, namely “smart” gold nanoparticles (AuNPs), in the detection of cancer cells with photothermal optical coherence tomography (PT-OCT). “Smart” AuNPs form aggregation in low pH condition, which is typical for cancer cells, and this aggregation results in a shift of their absorption spectrum. A PT-OCT system was developed to detect this pH-induced aggregation by combining an OCT light source and a laser with 660 nm in wavelength for photothermal excitation. Optical detection of pH-induced aggregation was tested with solution samples at two different pH conditions. An increase in optical path length (OPL ...

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    12. Combined two-photon microscopy and angiographic optical coherence tomography

      Combined two-photon microscopy and angiographic optical coherence tomography

      A combined two-photon microscopy (TPM) and angiographic optical coherence tomography (OCT) is developed, which can provide molecular, cellular, structural, and vascular information of tissue specimens in vivo . This combined system is implemented by adding an OCT vasculature visualization method to the previous combined TPM and OCT, and then is applied to in vivo tissue imaging. Two animal models, a mouse brain cranial window model and a mouse ear cancer model, are used. Both molecular, cellular information at local regions of tissues, and structural, vascular information at relatively larger regions are visualized in the same sections. In vivo tissue microenvironments are ...

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    13. In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography

      In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography

      The accurate determination of burn depth is critical in the clinical management of burn wounds. Polarization-sensitive optical coherence tomography (PS-OCT) has been proposed as a potentially non-invasive method for determining burn depth by measuring thermally induced changes in the structure and birefringence of skin, and has been investigated in pre-clinical burn studies with animal models and ex vivo human skin. In this study, we applied PS-OCT to the in-vivo imaging of two pediatric burn patients. Deep and superficial burned skins along with contralateral controls were imaged in 3D. The imaging size was 8  mm×6  mm×2  mm in width ...

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    14. Measurement of anisotropic reflection of flowing blood using optical coherence tomography

      Measurement of anisotropic reflection of flowing blood using optical coherence tomography
      Light reflectance of blood is a complex phenomenon affected by hematocrit and red blood cell (RBC) aggregation (rouleaux formation). According to the hypothesis that RBC rouleaux are aligned with the direction of blood flow, the spatial alignment of RBC rouleaux, as well as their size and quantity in the blood, may also affect light reflectance. The present study aims to investigate the effect of the spatial alignment and distribution of RBC rouleaux on light reflection using optical coherence tomography (OCT). Blood flow velocity and reflectance profiles in a rat jugular-femoral bypass loop were simultaneously measured using a Doppler swept-source OCT ...
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    15. Feature Of The Week 9/18/11: Combined Two-Photon Microscopy and Optical Coherence Tomography Using Individually Optimized Sources

      Feature Of The Week 9/18/11: Combined Two-Photon Microscopy and Optical Coherence Tomography Using Individually Optimized Sources
      Researchers from Phohang University of Science and Technology (POSTECH) in South Korea recent published an article on combined two-phton microscopy and optical coherence tomography using individually optimized sources. Below is a summary of that work.The combination of two-photon microscopy (TPM) and optical coherence tomography (OCT) is useful in conducting in-vivo tissue studies, because they provide complementary information regarding tissues. In the present study, we developed a new combined system using separate light sources and scanners for individually optimal imaging conditions. TPM used a Ti-Sapphire laser and provided molecular and cellular information in microscopic tissue regions. Meanwhile, OCT used a ...
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    16. Combined two-photon microscopy and optical coherence tomography using individually optimized sources

      Combined two-photon microscopy and optical coherence tomography using individually optimized sources
      The combination of two-photon microscopy (TPM) and optical coherence tomography (OCT) is useful in conducting in-vivo tissue studies, because they provide complementary information regarding tissues. In the present study, we developed a new combined system using separate light sources and scanners for individually optimal imaging conditions. TPM used a Ti-Sapphire laser and provided molecular and cellular information in microscopic tissue regions. Meanwhile, OCT used a wavelength-swept source centered at 1300 nm and provided structural information in larger tissue regions than TPM. The system was designed to do simultaneous imaging by combining light from both sources. TPM and OCT had the ...
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    17. Polarization-Sensitive Optical Coherence Tomography Imaging of Benign and Malignant Laryngeal Lesions: An In Vivo Study

      Polarization-Sensitive Optical Coherence Tomography Imaging of Benign and Malignant Laryngeal Lesions: An In Vivo Study
      Objective. Optical coherence tomography (OCT), an imaging technology that provides cross-sectional subsurface tissue structure images using back-scattered light, is a promising noninvasive imaging modality for in vivo assessment of vocal fold layered microstructure. Polarization-sensitive OCT (PS-OCT) augments conventional OCT by detecting changes in the polarization state of reflected light. This study imaged various benign and malignant laryngeal pathologies in patients undergoing direct laryngoscopy under general anesthesia to determine whether PS-OCT would provide useful additional information about vocal fold microstructure and glottic surface pathology. Study Design. Prospective clinical trial. Setting. Tertiary care center. Subjects and Methods. Twenty-three patients who were undergoing ...
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    18. Laryngeal imaging with polarization-sensitive optical coherence tomography

      Laryngeal imaging with polarization-sensitive optical coherence tomography

      Objectives/Hypothesis: Optical coherence tomography (OCT), an imaging technology that provides crosssectional subsurface tissue structure images using backscattered light, is a promising noninvasive, imaging modality for in-vivo assessment of vocal fold layered microstructure. Polarization-sensitive OCT (PS-OCT) augments conventional OCT by detecting changes in the polarization state of reflected light. This study imaged various benign laryngeal pathologies in patients undergoing direct laryngoscopy under general anesthesia to determine whether PS-OCT would provide useful additional information about vocal fold microstructure and glottic surface pathology. Study Design:Prospective clinical trial. Methods: Eighteen patients who were undergoing microlaryngoscopy under general anesthesia for benign glottic disease ...

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    19. Polarization-sensitive optical frequency domain imaging based on unpolarized light

      Polarization-sensitive optical frequency domain imaging based on unpolarized light
      Polarization-sensitive optical coherence tomography (PS-OCT) is an augmented form of OCT, providing 3D images of both tissue structure and polarization properties. We developed a new method of polarization-sensitive optical frequency domain imaging (PS-OFDI), which is based on a wavelength-swept source. In this method the sample was illuminated with unpolarized light, which was composed of two orthogonal polarization states (i.e., separated by 180° in the Poincaré sphere) that are uncorrelated to each other. Reflection of these polarization states from within the sample was detected simultaneously and independently using a frequency multiplexing scheme. This simultaneous sample probing with two polarization states ...
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    20. In vivo 3D human vocal fold imaging with polarization sensitive optical coherence tomography and a MEMS scanning catheter

      In vivo 3D human vocal fold imaging with polarization sensitive optical coherence tomography and a MEMS scanning catheter
      We present in-vivo 3D human vocal fold images with polarization sensitive optical coherence tomography (PS-OCT). Characterizing the extent and location of vocal fold lesions provides useful information in guiding surgeons during phonomicrosurgery. Previous studies showed that PS-OCT imaging can distinguish vocal fold lesions from normal tissue, but these studies were limited to 2D cross-sectional imaging and were susceptible to sampling error. In-vivo 3D endoscopic imaging was performed by using a recently developed 2-axis MEMS scanning catheter and a spectral domain OCT (SD-OCT), running at 18.5 frames/s. Imaging was performed in the operating room with patients under general anesthesia ...
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    21. Real-time tracking of vocal fold injections with optical coherence tomography

      Abstract Objectives/Hypothesis: Optical coherence tomography (OCT) is a promising new imaging modality that can help discern the layered microstructure of vocal folds. In the future, subepithelial injections of implants will improve vocal fold pliability where there is stiffness of phonatory mucosa. Using OCT both to delineate the depth of subepithelial injections real-time and to serially image the implant over time would be valuable, and has not been demonstrated previously. Study Design: Ex vivo study using excised calf larynges and survival study using canines in vivo. Methods: An investigation was done employing real-time OCT imaging of subepithelial injection pulses into ...
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    22. Monitoring mouse retinal degeneration with high-resolution spectral-domain optical coherence tomography

      Progression of retinal degeneration in a mouse model was studied in vivo with high-resolution spectral-domain optical coherence tomography (SD-OCT). Imaging in 3D with high depth resolution (<3 μm), SD-OCT resolved all the major layers of the retina of control C57BL/6J mice. Images of transgenic mice having a null mutation of the rhodopsin gene revealed the anatomical consequences of retinal degeneration: thinning of the outer retina, including the outer plexiform layer (OPL), outer nuclear layer (ONL), and inner and outer segments (IS/OS). We monitored the progression of retinal degeneration in rd1 mice (C3H/HeJ) by periodically imaging the same ...
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    23. Two-axis magnetically-driven MEMS scanning catheter for endoscopic high-speed optical coherence tomography

      Ki Hean Kim, B. H. Park, Gopi N. Maguluri, Tom W. Lee, Fran J. Rogomentich, Mirela G. Bancu, Brett E. Bouma, Johannes F. de Boer, Jonathan J. Bernstein A two-axis scanning catheter was developed for 3D endoscopic imaging with spectral domain optical coherence tomography (SD-OCT). The catheter incorporates a micro-mirror scanner implemented with microelectromechanical systems (MEMS) technology: the micro-mirror is mounted on a two-axis gimbal ... [Opt. Express 15, 18130-18140 (2007)]
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    1-23 of 23
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  2. Topics in the News

    1. (23 articles) Ki Hean Kim
    2. (8 articles) Harvard University
    3. (8 articles) Massachusetts General Hospital
    4. (7 articles) Johannes F. de Boer
    5. (5 articles) Taejun Wang
    6. (4 articles) Yonsei University
    7. (4 articles) VU University Amsterdam
    8. (4 articles) B. Hyle Park
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    In vivo 3D human vocal fold imaging with polarization sensitive optical coherence tomography and a MEMS scanning catheter Polarization-sensitive optical frequency domain imaging based on unpolarized light Polarization-Sensitive Optical Coherence Tomography Imaging of Benign and Malignant Laryngeal Lesions: An In Vivo Study Combined two-photon microscopy and optical coherence tomography using individually optimized sources Feature Of The Week 9/18/11: Combined Two-Photon Microscopy and Optical Coherence Tomography Using Individually Optimized Sources Measurement of anisotropic reflection of flowing blood using optical coherence tomography In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography Medical treatment of inflammatory punctual stenosis monitored by anterior segment optical coherence tomography Development and Validation of a Deep Learning System for Diagnosing Glaucoma Using Optical Coherence Tomography Methylene blue-filled biodegradable polymer particles as a contrast agent for optical coherence tomography Optical coherence tomography for thyroid pathology: 3D analysis of tissue microstructure Mathematical Analysis of Texture Indicators for the Segmentation of Optical Coherence Tomography Images