1. Articles from Wihan Kim

    1-11 of 11
    1. Vector of motion measurements in the living cochlea using a 3D OCT vibrometry system

      Vector of motion measurements in the living cochlea using a 3D OCT vibrometry system

      Optical coherence tomography (OCT) has become an important tool for measuring the vibratory response of the living cochlea. It stands alone in its capacity to measure the intricate motion of the hearing organ through the surrounding otic capsule bone. Nevertheless, as an extension of phase-sensitive OCT, it is only capable of measuring motion along the optical axis. Hence, measurements are 1-D. To overcome this limitation and provide a measure of the 3-D vector of motion in the cochlea, we developed an OCT system with three sample arms in a single interferometer. Taking advantage of the long coherence length of our ...

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    2. In vivo functional imaging of the human middle ear with a hand-held optical coherence tomography device

      In vivo functional imaging of the human middle ear with a hand-held optical coherence tomography device

      We describe an optical coherence tomography and vibrometry system designed for portable hand-held usage in the otology clinic on awake patients. The system provides clinically relevant point-of-care morphological imaging with 14-44 µm resolution and functional vibratory measures with sub-nanometer sensitivity. We evaluated various new approaches for extracting functional information including a multi-tone stimulus, a continuous chirp stimulus, and alternating air and bone stimulus. We also explored the vibratory response over an area of the tympanic membrane (TM) and generated TM thickness maps. Our results suggest that the system can provide real-time in vivo imaging and vibrometry of the ear and ...

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    3. Dual-modality optical coherence tomography and frequency-domain fluorescence lifetime imaging microscope system for intravascular imaging

      Dual-modality optical coherence tomography and frequency-domain fluorescence lifetime imaging microscope system for intravascular imaging

      Significance: Detailed biochemical and morphological imaging of the plaque burdened coronary arteries holds the promise of improved understanding of atherosclerosis plaque development, ultimately leading to better diagnostics and therapies. Aim: Development of a dual-modality intravascular catheter supporting swept-source optical coherence tomography (OCT) and frequency-domain fluorescence lifetime imaging (FD-FLIM) of endogenous fluorophores with UV excitation. Approach: We instituted a refined approach to endoscope development that combines simulation in a commercial ray tracing program, fabrication, and a measurement method for optimizing ball-lens performance. With this approach, we designed and developed a dual-modality catheter endoscope based on a double-clad fiber supporting OCT through ...

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    4. Methylene blue-filled biodegradable polymer particles as a contrast agent for optical coherence tomography

      Methylene blue-filled biodegradable polymer particles as a contrast agent for optical coherence tomography

      Optical coherence tomography (OCT) images largely lack molecular information or molecular contrast. We address that issue here, reporting on the development of biodegradable micro and nano-spheres loaded with methylene blue (MB) as molecular contrast agents for OCT. MB is a constituent of FDA approved therapies and widely used as a dye in off-label clinical applications. The sequestration of MB within the polymer reduced toxicity and improved signal strength by drastically reducing the production of singlet oxygen and leuco-MB. The former leads to tissue damage and the latter to reduced image contrast. The spheres are also strongly scattering which improves molecular ...

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    5. Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system

      Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system

      We have developed a highly phase stable optical coherence tomography and vibrometry system that attaches directly to the accessory area of a surgical microscope common to both the otology clinic and operating room. Careful attention to minimizing sources of phase noise has enabled a system capable of measuring vibrations of the middle ear with a sensitivity of < 5 pm in an awake human patient. The system is shown to be capable of collecting a wide range of information on the morphology and function of the ear in live subjects, including frequency tuning curves below the hearing threshold, maps of tympanic ...

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    6. Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window

      Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window

      A highly phase stable hand-held (HH) endoscopic system has been developed for optical coherence tomography and vibrometry. Designed to transit the ear canal to the middle ear space and peer through the round window (RW), it is capable of imaging the vibratory function of the cochlear soft tissues with subnanometer scale sensitivity. A side-looking, 9 cm long rigid endoscope with a distal diameter of 1.2 mm, was able to fit within the RW niche and provide imaging access. The phase stability was achieved in part by fully integrating a Michelson interferometer into the HH device. Ex vivo imaging of ...

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    7. Contrast enhancement of pump-probe optical coherence tomography (PP-OCT) based molecular imaging using methylene blue loaded PLGA particles

      Contrast enhancement of pump-probe optical coherence tomography (PP-OCT) based molecular imaging using methylene blue loaded PLGA particles

      Atherosclerosis, a condition in which plaque accumulates on the inner wall of arteries, is often recognized as a precursor to cardiovascular diseases (CVDs), the most common causes of death in the US. Optical Coherence Tomography (OCT) is an intravascular optical diagnosis tool, which can be used to obtain high resolution morphological images of atherosclerotic plaque. However, atherosclerotic plaque components, such as macrophages, can be misclassified due to their signal similarities to fibrin accumulations, cholesterol crystals and microcalcifications. To overcome these challenges, we develop a biocompatible contrast agent to enhance molecular imaging of a Pump-Probe OCT (PPOCT) system. Methylene blue (MB ...

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    8. Molecular Imaging in Optical Coherence Tomography

      Molecular Imaging in Optical Coherence Tomography

      Optical coherence tomography (OCT) is a medical imaging technique that provides tomographic images at micron scales in three dimensions and high speeds. The addition of molecular contrast to the available morphological image holds great promise for extending OCT’s impact in clinical practice and beyond. Fundamental limitations prevent OCT from directly taking advantage of powerful molecular processes such as fluorescence emission and incoherent Raman scattering. A wide range of approaches is being researched to provide molecular contrast to OCT. Here we review those approaches with particular attention to those that derive their molecular contrast directly from modulation of the OCT ...

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    9. In vivo molecular contrast OCT imaging of methylene blue

      In vivo molecular contrast OCT imaging of methylene blue

      An 830-nm spectral-domain optical coherence tomography (OCT) system with an integrated 663-nm diode pump laser has been developed to enable molecular contrast OCT imaging of methylene blue (MB), a common vital dye used clinically. The introduction of the 663-nm diode laser, which acts as the pump in this implementation of pump-probe OCT (PPOCT), represents a minor modification to an otherwise typical OCT system. A newly developed background subtraction technique completely removes all background from intensity noise at the pump modulation frequency, simplifying the interpretation of PPOCT images. These developments have enabled the first in vivo imaging of MB with PPOCT ...

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    10. Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-known photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    11. In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-know photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    1-11 of 11
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    1. (10 articles) Texas A&M University
    2. (3 articles) University of Southern California
    3. (3 articles) UCLA
    4. (2 articles) Heidelberg Engineering
    5. (1 articles) FDA
    6. (1 articles) Jichi Medical University
    7. (1 articles) Stanford University
    8. (1 articles) University of Florence
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    In vivo pump-probe optical coherence tomography imaging in Xenopus laevis Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis In vivo molecular contrast OCT imaging of methylene blue Molecular Imaging in Optical Coherence Tomography Contrast enhancement of pump-probe optical coherence tomography (PP-OCT) based molecular imaging using methylene blue loaded PLGA particles Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window Picometer scale vibrometry in the human middle ear using a surgical microscope based optical coherence tomography and vibrometry system Methylene blue-filled biodegradable polymer particles as a contrast agent for optical coherence tomography Dual-modality optical coherence tomography and frequency-domain fluorescence lifetime imaging microscope system for intravascular imaging In vivo functional imaging of the human middle ear with a hand-held optical coherence tomography device The truth about invisible posterior vitreous structures The Influence of Eyelid Position and Environmental Conditions on the Corneal Changes in Early Postmortem Interval: A Prospective, Multicentric OCT Study