1. Articles from B. Hyle Park

    1-16 of 16
    1. Interferometric mapping of material properties using thermal perturbation

      Interferometric mapping of material properties using thermal perturbation

      Optical phase changes induced by transient perturbations provide a sensitive measure of material properties. We demonstrate the high sensitivity and speed of such methods, using two interferometric techniques: quantitative phase imaging (QPI) in transmission and phase-resolved optical coherence tomography (OCT) in reflection. Shot-noise–limited QPI can resolve energy deposition of about 3.4 mJ/cm 2 in a single pulse, which corresponds to 0.8 °C temperature rise in a single cell. OCT can detect deposition of 24 mJ/cm 2 energy between two scattering interfaces producing signals with about 30-dB signal-to-noise ratio (SNR), and 4.7 mJ/cm 2 ...

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    2. OCT intensity and phase fluctuations correlated with activity-dependent neuronal calcium dynamics in the Drosophila CNS [Invited]

      OCT intensity and phase fluctuations correlated with activity-dependent neuronal calcium dynamics in the Drosophila CNS [Invited]

      Phase-resolved OCT and fluorescence microscopy were used simultaneously to examine stereotypic patterns of neural activity in the isolated Drosophila central nervous system. Both imaging modalities were focused on individually identified bursicon neurons known to be involved in a fixed action pattern initiated by ecdysis-triggering hormone. We observed clear correspondence of OCT intensity, phase fluctuations, and activity-dependent calcium-induced fluorescence.

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    3. Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography

      Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography

      Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth-resolved cross-sectional images. In this study, OCT was used to detect changes in the optical properties of cortical tissue in vivo in mice during the induction of global (pentylenetetrazol) and focal (4-aminopyridine) seizures. Through the use of a confidence interval statistical method on depth-resolved volumes of attenuation coefficient, we demonstrated localization of regions exhibiting both significant positive and negative changes in attenuation coefficient, as well as differentiating between global and focal seizure propagation.

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    4. In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

      In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

      Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitive-optical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve microenvironment through measurements of birefringence after applying a nerve crush injury in a rat model. Initial loss of function and subsequent recovery were demonstrated by calculating the sciatic function index ...

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    5. Decreased light attenuation in cerebral cortex during cerebral edema detected using optical coherence tomography

      Decreased light attenuation in cerebral cortex during cerebral edema detected using optical coherence tomography

      Cerebral edema develops in response to a variety of conditions, including traumatic brain injury and stroke, and contributes to the poor prognosis associated with these injuries. This study examines the use of optical coherence tomography (OCT) for detecting cerebral edema in vivo . Three-dimensional imaging of an in vivo water intoxication model in mice was performed using a spectral-domain OCT system centered at 1300 nm. The change in attenuation coefficient was calculated and cerebral blood flow was analyzed using Doppler OCT techniques. We found that the average attenuation coefficient in the cerebral cortex decreased over time as edema progressed. The initial ...

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    6. Investigation of Biodegradable Composite Coated Magnesium Alloy Using Optical Coherence Tomography

      Investigation of Biodegradable Composite Coated Magnesium Alloy Using Optical Coherence Tomography

      Optical coherence tomography (OCT) was used to characterize poly (lactic-co-glycolic acid) (PLGA) and nanophase hydroxyapatite (nHA) / PLGA coatings on magnesium (Mg) substrates before and after immersion in revised simulated body fluid (rSBF) under standard cell culture conditions. The OCT images clearly showed: the surface of the coatings, the metallic surface underneath the coatings, the presence of a dispersed phase within the polymer matrix, and defects and structural changes to the coatings. This study demonstrated the potential utility of OCT for performing quality assurance tests and for tracking the physical effects of degradation upon biomedical implants due to its ability to ...

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    7. A common-path optical coherence tomography based electrode for structural imaging of nerves and recording of action potentials

      A common-path optical coherence tomography based electrode for structural imaging of nerves and recording of action potentials

      Current technologies for monitoring neural activity either use different variety of electrodes (electrical recording) or require contrast agents introduced exogenously or through genetic modification (optical imaging). Here we demonstrate an optical method for non-contact and contrast agent free detection of nerve activity using phase-resolved optical coherence tomography (pr-OCT). A common-path variation of the pr-OCT is recently implemented and the developed system demonstrated the capability to detect rapid transient structural changes that accompany neural spike propagation. No averaging over multiple trials was required, indicating its capability of single-shot detection of individual impulses from functionally stimulated Limulus optic nerve. The strength of ...

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    8. OCT News 2013 Student Paper Awarded to Carissa Reynolds from University of California Riverside

      OCT News 2013 Student Paper Awarded to Carissa Reynolds from University of California Riverside

      Carissa Reynolds from University of California Riverside was a winner of the 2013 OCT News Student paper award for her submission “Using Optical Coherence Tomography to Detect Cerebral Edema.” Below is a summary of her work: Cerebral edema, an increase in brain water content, is responsible for significant morbidity and mortality among patients suffering from neurological disorders such as traumatic brain injury, stroke, brain tumor and infection. Cerebral edema develops in response to these conditions and leads to further clinical deterioration by, for example, raising the intracranial pressure (ICP), disrupting blood flow to the brain and/or causing brain herniation ...

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    9. Feature Of The Week 10/28/12: UC Riverside Presents GPU Accelerated Real-Time Multi-Functional SD-OCT system at 1300nm

      Feature Of The Week 10/28/12: UC Riverside Presents GPU Accelerated Real-Time Multi-Functional SD-OCT system at 1300nm

      We present a GPU accelerated multi-functional spectral domain optical coherence tomography system at 1300nm. The system is capable of real-time processing and display of every intensity image, comprised of 512 pixels by 2048 A-lines acquired at 20 frames per second. The update rate for all four images with size of 512 pixels by 2048 A-lines simultaneously (intensity, phase retardation, flow and en face view) is approximately 10 frames per second. Additionally, we report for the first time the characterization of phase retardation and diattenuation by a sample comprised of a stacked set of polarizing film and wave plate. The calculated ...

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    10. In vivo detection of cortical optical changes associated with seizure activity with optical coherence tomography

      In vivo detection of cortical optical changes associated with seizure activity with optical coherence tomography
      The most common technology for seizure detection is with electroencephalography (EEG), which has low spatial resolution and minimal depth discrimination. Optical techniques using near-infrared (NIR) light have been used to improve upon EEG technology and previous research has suggested that optical changes, specifically changes in near-infrared optical scattering, may precede EEG seizure onset in in vivo models. Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth resolved cross-sectional images. In this study, OCT was used to detect changes in optical properties of cortical tissue in vivo in mice before and during the induction ...
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    11. GPU accelerated real-time multi-functional spectral-domain optical coherence tomography system at 1300nm

      GPU accelerated real-time multi-functional spectral-domain optical coherence tomography system at 1300nm

      We present a GPU accelerated multi-functional spectral domain optical coherence tomography system at 1300nm. The system is capable of real-time processing and display of every intensity image, comprised of 512 pixels by 2048 A-lines acquired at 20 frames per second. The update rate for all four images with size of 512 pixels by 2048 A-lines simultaneously (intensity, phase retardation, flow and en face view) is approximately 10 frames per second. Additionally, we report for the first time the characterization of phase retardation and diattenuation by a sample comprised of a stacked set of polarizing film and wave plate. The calculated ...

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    12. 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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    13. Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

      Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

      We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve ...

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    14. 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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    15. 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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    16. Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics

      Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics

      Various layers of the retina are well known to alter the polarization state of light. Such changes in polarization may be a sensitive indicator of tissue structure and function, and as such have gained increased clinical attention. Here we demonstrate a polarization-sensitive optical coherence tomography (PS-OCT) system that incorporates adaptive optics (AO) in the sample arm and a single line scan camera in the detection arm. We quantify the benefit of AO for PS-OCT in terms of signal-to-noise, lateral resolution, and speckle size. Double pass phase retardation per unit depth values ranging from 0.25°/μm to 0.65°/μm ...

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    1-16 of 16
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  2. Topics in the News

    1. (16 articles) B. Hyle Park
    2. (15 articles) UC Riverside
    3. (8 articles) Yan Wang
    4. (7 articles) M. Shahidul Islam
    5. (6 articles) Massachusetts General Hospital
    6. (6 articles) VU University Amsterdam
    7. (6 articles) Johannes F. de Boer
    8. (5 articles) Harvard University
    9. (3 articles) Ki Hean Kim
    10. (2 articles) Carissa L. Reynolds
    11. (1 articles) UCLA
    12. (1 articles) Srinivas R. Sadda
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    Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics 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 Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography GPU accelerated real-time multi-functional spectral-domain optical coherence tomography system at 1300nm In vivo detection of cortical optical changes associated with seizure activity with optical coherence tomography Feature Of The Week 10/28/12: UC Riverside Presents GPU Accelerated Real-Time Multi-Functional SD-OCT system at 1300nm OCT News 2013 Student Paper Awarded to Carissa Reynolds from University of California Riverside A common-path optical coherence tomography based electrode for structural imaging of nerves and recording of action potentials Close Assessment and Testing for Chronic Graft Versus Host Disease, CATCH Study GaAs-Based InPBi Quantum Dots for High Efficiency Super-Luminescence Diodes