1. Articles from Jonghwan Lee

    1-13 of 13
    1. Design and optimization of line-field optical coherence tomography at visible wavebands

      Design and optimization of line-field optical coherence tomography at visible wavebands

      Parallel line-field Fourier-domain optical coherence tomography (LF-FDOCT) has emerged to enable relatively higher speeds than the conventional FDOCT system. In the LF-FDOCT, one B-scan is captured at a time instead of scanning the beam to acquire hundreds of A-scans. On the other hand, spectroscopic OCT using the visible waveband provides absorption information over multiple wavelengths at each voxel. This information of spectral absorption enables quantitative measurement of blood oxygenation, voxel by voxel. Here, we presented the design and optimization of a LF-FDOCT system at the visible waveband (520–620 nm), especially using a generic Camera Link area sensor (2048 × 1088 ...

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      Mentions: Brown University
    2. Deep learning toolbox for automated enhancement, segmentation, and graphing of cortical optical coherence tomography microangiograms

      Deep learning toolbox for automated enhancement, segmentation, and graphing of cortical optical coherence tomography microangiograms

      Optical coherence tomography angiography (OCTA) is becoming increasingly popular for neuroscientific study, but it remains challenging to objectively quantify angioarchitectural properties from 3D OCTA images. This is mainly due to projection artifacts or “tails” underneath vessels caused by multiple-scattering, as well as the relatively low signal-to-noise ratio compared to fluorescence-based imaging modalities. Here, we propose a set of deep learning approaches based on convolutional neural networks (CNNs) to automated enhancement, segmentation and gap-correction of OCTA images, especially of those obtained from the rodent cortex. Additionally, we present a strategy for skeletonizing the segmented OCTA and extracting the underlying vascular graph ...

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      Mentions: Brown University
    3. MATLAB code and data processing guide for Dynamic Light Scattering-Optical Coherence Tomography

      MATLAB code and data processing guide for Dynamic Light Scattering-Optical Coherence Tomography

      This guide is for post data processing of DLSOCT, which outputs axial velocity (Vz), transverse velocity (Vx), total velocity(V), the ratio of static component (Ms), the ratio of dynamic component (Mf), and fitting accuracy (R). The speed upper limit is determined by OCT system Aline rate and 3Dvoxel size.

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    4. Measurement of shear-induced diffusion of red blood cells using dynamic light scattering-optical coherence tomography

      Measurement of shear-induced diffusion of red blood cells using dynamic light scattering-optical coherence tomography

      Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile, and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a ...

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    5. Shear‐induced diffusion of red blood cells measured with dynamic light scattering‐optical coherence tomography

      Shear‐induced diffusion of red blood cells measured with dynamic light scattering‐optical coherence tomography

      Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering‐optical coherence tomography (DLS‐OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution‐constrained three‐dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this ...

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    6. Shear-Induced Diffusion of Red Blood Cells Measured with Dynamic Light Scattering-Optical Coherence Tomography

      Shear-Induced Diffusion of Red Blood Cells Measured with Dynamic Light Scattering-Optical Coherence Tomography

      Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress, and the diffusion coefficient of red blood cells (RBCs), are fundamental to understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT ...

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    7. Optical coherence tomography imaging of capillary reperfusion after ischemic stroke

      Optical coherence tomography imaging of capillary reperfusion after ischemic stroke

      Although progress has been made for recanalization therapies after ischemic stroke, post-treatment imaging studies show that tissue reperfusion cannot be attained despite satisfactory recanalization in a significant percentage of patients. Hence, investigation of microcirculatory changes in both surface and deep cortical levels after ischemia reperfusion is important for understanding the post-stroke blood flow dynamics. In this study, we applied optical coherence tomography (OCT) imaging of cerebral blood flow for the quantification of the microcirculatory changes. We obtained OCT microangiogram of the brain cortex in a mouse stroke model and analyzed the data to trace changes in the capillary perfusion level ...

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    8. Statistical intensity variation analysis for rapid volumetric imaging of capillary network flux

      Statistical intensity variation analysis for rapid volumetric imaging of capillary network flux

      We present a novel optical coherence tomography (OCT)-based technique for rapid volumetric imaging of red blood cell (RBC) flux in capillary networks. Previously we reported that OCT can capture individual RBC passage within a capillary, where the OCT intensity signal at a voxel fluctuates when an RBC passes the voxel. Based on this finding, we defined a metric of statistical intensity variation (SIV) and validated that the mean SIV is proportional to the RBC flux [RBC/s] through simulations and measurements. From rapidly scanned volume data, we used Hessian matrix analysis to vectorize a segment path of each capillary ...

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    9. Multiple-capillary measurement of RBC speed, flux, and density with optical coherence tomography

      Multiple-capillary measurement of RBC speed, flux, and density with optical coherence tomography

      As capillaries exhibit heterogeneous and fluctuating dynamics even during baseline, a technique measuring red blood cell (RBC) speed and flux over many capillaries at the same time is needed. Here, we report that optical coherence tomography can capture individual RBC passage simultaneously over many capillaries located at different depths. Further, we demonstrate the ability to quantify RBC speed, flux, and linear density. This technique will provide a means to monitor microvascular flow dynamics over many capillaries at different depths at the same time.

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    10. Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography

      Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography

      This paper describes a novel optical method for label-free quantitative imaging of cerebral blood flow (CBF) and intracellular motility (IM) in the rodent cerebral cortex. This method is based on a technique that integrates dynamic light scattering (DLS) and optical coherence tomography (OCT), named DLS–OCT. The technique measures both the axial and transverse velocities of CBF, whereas conventional Doppler OCT measures only the axial one. In addition, the technique produces a three-dimensional map of the diffusion coefficient quantifying nontranslational motions. In the DLS–OCT diffusion map, we observed high-diffusion spots, whose locations highly correspond to neuronal cell bodies and ...

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    11. Dynamic light scattering optical coherence tomography

      Dynamic light scattering optical coherence tomography

      We introduce an integration of dynamic light scattering (DLS) and optical coherence tomography (OCT) for high-resolution 3D imaging of heterogeneous diffusion and flow. DLS analyzes fluctuations in light scattered by particles to measure diffusion or flow of the particles, and OCT uses coherence gating to collect light only scattered from a small volume for high-resolution structural imaging. Therefore, the integration of DLS and OCT enables high-resolution 3D imaging of diffusion and flow. We derived a theory under the assumption that static and moving particles are mixed within the OCT resolution volume and the moving particles can exhibit either diffusive or ...

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    12. Frequency-domain measurement of neuronal activity using dynamic optical coherence tomography

      Frequency-domain measurement of neuronal activity using dynamic optical coherence tomography

      We report preliminary results on high-resolution in vivo imaging of fast intrinsic optical signals of neuronal activity in the frequency domain. An optical coherence tomography (OCT) system was used for dynamic imaging of the cross section of rodent somatosensory cortex at 250 frame/s. Neurons in the cortex were excited by contralateral forepaw stimulation, and the ipsilateral forepaw was stimulated as a control. Hemodynamic responses at the cortical surface, which were simultaneously measured using a CCD, confirmed that forepaw stimulation properly evoked neuronal activation. Analysis of the OCT signal in the frequency domain resulted in that the spectrum significantly increased ...

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    13. Motion correction for phase-resolved dynamic optical coherence tomography imaging of rodent cerebral cortex

      Motion correction for phase-resolved dynamic optical coherence tomography imaging of rodent cerebral cortex

      Cardiac and respiratory motions in animals are the primary source of image quality degradation in dynamic imaging studies, especially when using phase-resolved imaging modalities such as spectral-domain optical coherence tomography (SD-OCT), whose phase signal is very sensitive to movements of the sample. This study demonstrates a method with which to compensate for motion artifacts in dynamic SD-OCT imaging of the rodent cerebral cortex. We observed that respiratory and cardiac motions mainly caused, respectively, bulk image shifts (BISs) and global phase fluctuations (GPFs). A cross-correlation maximization-based shift correction algorithm was effective in suppressing BISs, while GPFs were significantly reduced by removing ...

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    1-13 of 13
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  2. Topics in the News

    1. (11 articles) David A. Boas
    2. (9 articles) Harvard University
    3. (9 articles) Massachusetts General Hospital
    4. (4 articles) Brown University
    5. (3 articles) Boston University
    6. (2 articles) James Y. Jiang
    7. (2 articles) Harsha Radhakrishnan
    8. (2 articles) Frédéric Lesage
    9. (2 articles) Thorlabs
    10. (1 articles) Vivek J. Srinivasan
    11. (1 articles) Yamagata University
    12. (1 articles) Bern University of Applied Sciences
    13. (1 articles) Medical University of Vienna
    14. (1 articles) University of Maryland
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    16. (1 articles) Vishali Gupta
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    Motion correction for phase-resolved dynamic optical coherence tomography imaging of rodent cerebral cortex Dynamic light scattering optical coherence tomography Frequency-domain measurement of neuronal activity using dynamic optical coherence tomography Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography Multiple-capillary measurement of RBC speed, flux, and density with optical coherence tomography Statistical intensity variation analysis for rapid volumetric imaging of capillary network flux Optical coherence tomography imaging of capillary reperfusion after ischemic stroke Shear-Induced Diffusion of Red Blood Cells Measured with Dynamic Light Scattering-Optical Coherence Tomography Measurement of shear-induced diffusion of red blood cells using dynamic light scattering-optical coherence tomography MATLAB code and data processing guide for Dynamic Light Scattering-Optical Coherence Tomography Hybrid registration of retinal fluorescein angiography and optical coherence tomography images of patients with diabetic retinopathy Optical Coherence Tomography Angiography Quality Across Three Multicenter Clinical Studies of Diabetic Retinopathy