1. Articles from Hongki Yoo

    1-23 of 23
    1. Lateral image reconstruction of optical coherence tomography using one-dimensional deep deconvolution network

      Lateral image reconstruction of optical coherence tomography using one-dimensional deep deconvolution network

      Background and objectives: Optical coherence tomography (OCT) is a cross-sectional imaging method utilizing a low coherence interferometry. The lateral resolution of the OCT is limited by the numerical aperture (NA) of the imaging lens. Using a high NA lens improves the lateral resolution but reduces the depth of focus (DOF). In this study, we propose a method to improve the lateral resolution of OCT images by end-to-end training of a deep 1-D deconvolution network without use of high-resolution images. Materials and methods: To improve the lateral resolution of the OCT, we trained the 1-D deconvolution network using lateral profiles of ...

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    2. 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 ...

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    3. 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 ...

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      Mentions: Korea University
    4. Utilization potential of intraluminal optical coherence tomography for the Eustachian tube

      Utilization potential of intraluminal optical coherence tomography for the Eustachian tube

      Imaging the Eustachian tube is challenging because of its complex anatomy and limited accessibility. This study fabricated a fiber-based optical coherence tomography (OCT) catheter and investigated its potential for assessing the Eustachian tube anatomy. A customized OCT system and an imaging catheter, termed the Eustachian OCT, were developed for visualizing the Eustachian tube. Three male swine cadaver heads were used to study OCT image acquisition and for subsequent histologic correlation. The imaging catheter was introduced through the nasopharyngeal opening and reached toward the middle ear. The OCT images were acquired from the superior to the nasopharyngeal opening before and after ...

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    5. Astigmatism-corrected endoscopic imaging probe for optical coherence tomography using soft lithography

      Astigmatism-corrected endoscopic imaging probe for optical coherence tomography using soft lithography

      In endoscopic optical coherence tomography, a transparent protective sheath is used to protect the optics and tissue. However, the sheath causes astigmatism, which degrades transverse resolution and signal-to-noise ratio due to the cylindrical lens effect. Generally used methods for correcting this astigmatism are complex, difficult to control precisely, high-cost, and increase the dimensions of the imaging probe. To overcome these problems, we have developed an astigmatism-corrected imaging probe with an epoxy window. The astigmatism is precisely and cost-effectively adjusted controlling the curvature radius of the epoxy window, which is produced by soft lithography. Using the fiber optic fusion splicing, the ...

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    6. Flexible endoscopic micro-optical coherence tomography for three-dimensional imaging of the arterial microstructure

      Flexible endoscopic micro-optical coherence tomography for three-dimensional imaging of the arterial microstructure

      Micro-optical coherence tomography (µOCT) is a novel imaging approach enabling visualization of the microstructures of biological tissues at a cellular or sub-cellular level. However, it has been challenging to develop a miniaturized flexible endoscopic µOCT probe allowing helical luminal scanning. In this study, we built a flexible endoscopic µOCT probe with an outer diameter of 1.2 mm, which acquires three-dimensional images of the arterial microstructures via helical scanning with an axial and lateral resolutions of 1.83 µm and 3.38 µm in air, respectively. Furthermore, the depth of focus of the µOCT imaging probe was extended two-fold using ...

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    7. 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 ...

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    8. 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 ...

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    9. Endoscopic micro-optical coherence tomography with extended depth of focus using a binary phase spatial filter

      Endoscopic micro-optical coherence tomography with extended depth of focus using a binary phase spatial filter

      Micro-optical coherence tomography (μOCT) is an advanced imaging technique that acquires a three-dimensional microstructure of biological samples with a high spatial resolution, up to 1 μm, by using a broadband light source and a high numerical aperture (NA) lens. As high NA produces a short depth of focus (DOF), extending the DOF is necessary to obtain a reasonable imaging depth. However, due to the complexity of optics and the limited space, it has been challenging to fabricate endoscopic μOCT, which is essential for clinical translation. Here, we report an endoscopic μOCT probe with an extended DOF by using a binary ...

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    10. 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 ...

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    11. Automated detection of vessel lumen and stent struts in intravascular optical coherence tomography to evaluate stent apposition and neointimal coverage

      Automated detection of vessel lumen and stent struts in intravascular optical coherence tomography to evaluate stent apposition and neointimal coverage

      Purpose: Intravascular optical coherence tomography (IV-OCT) is a high-resolution imaging method used to visualize the microstructure of arterial walls in vivo . IV-OCT enables the clinician to clearly observe and accurately measure stent apposition and neointimal coverage of coronary stents, which are associated with side effects such as in-stent thrombosis. In this study, the authors present an algorithm for quantifying stent apposition and neointimal coverage by automatically detecting lumen contours and stent struts in IV-OCT images. Methods: The algorithm utilizes OCT intensity images and their first and second gradient images along the axial direction to detect lumen contours and stent strut ...

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    12. 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 ...

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    13. Design and fabrication of an optical probe with a phase filter for extended depth of focus

      Design and fabrication of an optical probe with a phase filter for extended depth of focus

      The trade-off between spot size and depth of focus (DOF) often limits the performance of optical systems, such as optical coherence tomography and optical tweezers. Although researchers have proposed various methods to extend the DOF in free-space optics, many are difficult to implement in miniaturized optical probes due to space limitations. In this study, we present an optical probe with an extended DOF using a binary phase spatial filter (BPSF). The BPSF pattern was fabricated on the distal tip of an optical probe with a diameter of 1 mm by replica molding soft lithography, which can be easily implemented in ...

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    14. A bi-directional assessment of spontaneous coronary artery dissection by three-dimensional flythrough rending of optical coherence tomography images

      A bi-directional assessment of spontaneous coronary artery dissection by three-dimensional flythrough rending of optical coherence tomography images

      A 71-year-old woman was admitted to our hospital due to unstable chest pain. Coronary angiography demonstrated a complex eccentric lesion with 80% narrowing of the right coronary arterial lumen ( Panel A ). Intravascular optical coherence tomography (IV-OCT) revealed typical characteristics of spontaneous coronary artery...

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    15. 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

      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

      In current study, we fully integrated near-infrared fluorescence (NIRF) molecular imaging into intravascular OCT structural imaging. The OCT/NIRF single catheter imaging clearly demonstrated the microstructure of atheromata and simultaneously identified ICG-enhancing macrophage abundant lipid-rich areas of the plaques. Ex vivo NIRF imaging evidently validated in vivo OCT-NIRF imaging. NIRF signals on ex vivo fluorescence reflectance imaging colocalized well with in vivo NIRF imaging. In vitro ICG cell uptake, correlative fluorescence microscopy, and histopathology corroborated the in vivo imaging findings. Herein, our research team have solved the issues critical for application of this OCT/NIRF imaging technology to clinical practice ...

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    16. 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

      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

      Background— Lipid-rich inflamed coronary plaques a reprone to rupture. The purpose of this study was to assess lipid-rich inflamed plaques invivo using fully integrated high-speed optical coherence tomography (OCT)/ near-infrared fluorescence (NIRF) molecular imaging with a Food and Drug Administration– a pproved indocyanine green (ICG). Methods a nd Results— A n integrated high-speed intravascular OCT/NIRF imaging c a theter a nd a du a l-mod a l OCT/NIRF system were constructed b a sed on a cl in ic a l OCT pl a tform. For imaging lipid-rich inflamed plaques, the Food and Drug Administration– approved NIRF-emitting ICG ...

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    17. Coronary Stent Fracture Complicated Multiple Aneurysms Confirmed by 3-Dimensional Reconstruction of Intravascular-Optical Coherence Tomography in a Patient Treated With Open-Cell Designed Drug-Eluting Stent

      Coronary Stent Fracture Complicated Multiple Aneurysms Confirmed by 3-Dimensional Reconstruction of Intravascular-Optical Coherence Tomography in a Patient Treated With Open-Cell Designed Drug-Eluting Stent

      A 55-year-old man with a previous history of cerebral infarct and hypertension presented to our cardiovascular center complaining of angina in November 2011. Chronic total occlusion in the proximal left anterior descending artery was identified by coronary angiography (Figure 1A). The patient subsequently underwent percutaneous coronary intervention. Wiring was done successfully with a tapered stiff wire (Conquest Pro 20; ASAHI INTECC). After multiple predilation, a single drug-eluting stent (3.0 × 18 mm) of an open-cell design and bioabsorbable polymer (Nobori; Terumo, Tokyo, Japan) was implanted using a 3.5-mm noncompliant balloon (inflation pressure, 24 atmospheric pressure; Quantum Maverick Balloon; Boston ...

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    18. Evaluation of optical reflectance techniques for imaging of alveolar structure

      Evaluation of optical reflectance techniques for imaging of alveolar structure

      Three-dimensional (3-D) visualization of the fine structures within the lung parenchyma could advance our understanding of alveolar physiology and pathophysiology. Current knowledge has been primarily based on histology, but it is a destructive two-dimensional (2-D) technique that is limited by tissue processing artifacts. Micro-CT provides high-resolution three-dimensional (3-D) imaging within a limited sample size, but is not applicable to intact lungs from larger animals or humans. Optical reflectance techniques offer the promise to visualize alveolar regions of the large animal or human lung with sub-cellular resolution in three dimensions. Here, we present the capabilities of three optical reflectance techniques, namely ...

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    19. Optical frequency domain imaging system and catheters for volumetric imaging of the human esophagus

      Optical frequency domain imaging system and catheters for volumetric imaging of the human esophagus

      Barrett's esophagus (BE) is a metaplastic disorder that can undergo dysplastic progression, leading to esophageal adenocarcinoma. Upper endoscopy is the standard of care for screening for BE, but this technique has a relatively low diagnostic accuracy and high cost due to the requirement of conscious sedation. Optical frequency domain imaging (OFDI) is a high-speed imaging modality that generates cross-sectional images of tissues with a resolution of approximately 10µm that is sufficient for detecting microscopic tissue architecture. In combination with a balloon-centering catheter, this method enables BE diagnosis over the entire distal esophagus.   Full Text: PDFReferences S. H. Yun ...

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    20. Intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo

      Intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo

      Advancing understanding of human coronary artery disease requires new methods that can be used in patients for studying atherosclerotic plaque microstructure in relation to the molecular mechanisms that underlie its initiation, progression and clinical complications, including myocardial infarction and sudden cardiac death. Here we report a dual-modality intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo using a combination of optical frequency domain imaging (OFDI) and near-infrared fluorescence (NIRF) imaging. By providing simultaneous molecular information in the context of the surrounding tissue microstructure, this new catheter could provide new opportunities for investigating coronary atherosclerosis and stent healing and for ...

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    21. Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography

      Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography

      Abstract  Intracoronary optical coherence tomography and optical frequency domain imaging (OFDI) have been utilized for two-dimensional and three-dimensional imaging of vascular microanatomy. Image quality and the spatial accuracy of multidimensional reconstructions, however, can be degraded due to artifacts resulting from relative motion between the intracoronary catheter and the vessel wall. To track the relative motion of a catheter with regard to the vessel, a motion tracking system was incorporated with a standard OFDI system by using wavelength division multiplexing techniques. Motion of the vessel was acquired by a frequency shift of the backscattered light caused by the Doppler effect. A ...

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    22. Barrett's Esophagus Screening Using Balloon-Based Optical Frequency Domain Imaging: A Comparison With Endoscopy

      Abstracts submitted to ASGE 2010. Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging modality that has been shown to accurately differentiate esophageal pathology relevant to screening and surveillance in Barrett's patients. We have previously demonstrated that optical frequency domain imaging (OFDI), a high speed 2nd generation embodiment of OCT, may be used to perform volumetric microscopy of the distal esophagus in patients. In this present study we compare the sensitivity of OFDI to endoscopy for the diagnosis of specialized intestinal metaplasia (SIM), using histopathology as the gold standard.

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    1-23 of 23
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    Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography Optical frequency domain imaging system and catheters for volumetric imaging of the human esophagus Evaluation of optical reflectance techniques for imaging of alveolar structure Coronary Stent Fracture Complicated Multiple Aneurysms Confirmed by 3-Dimensional Reconstruction of Intravascular-Optical Coherence Tomography in a Patient Treated With Open-Cell Designed Drug-Eluting Stent 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 Design and fabrication of an optical probe with a phase filter for extended depth of focus 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 Utilization potential of intraluminal optical coherence tomography for the Eustachian tube OCT Macular Volume as a Predictor of Vascular Leakage in Uveitis Vanderbilt University Receives NIH Grant for Smart-phone-integrated, non-invasive, depth-resolved optical spectroscopy for the detection of neonatal jaundice University of North Carolina at Chapel Hill Receives NIH Grant for Predicting the Need for Surgery in Pediatric Subglottic Stenosis using Airway Elastography Derived from Endoscopic OCT and Intraluminal Pressure Measurement