1. Articles from congwu du

    1-12 of 12
    1. Cerebral capillary flow imaging by wavelength‐division‐multiplexing swept‐source optical Doppler tomography

      Cerebral capillary flow imaging by wavelength‐division‐multiplexing swept‐source optical Doppler tomography

      Swept‐source optical coherence tomography has demonstrated the unique advantages for fast imaging rate and long imaging distance, however, limited axial resolution and complex phase noises restrict swept‐source optical coherence Doppler tomography (SS‐ODT) for quantitative capillary blood flow imaging in the deep cortices. Here, the wavelength‐division‐multiplexing optical Doppler tomography (WDM‐ODT) method, which divides a single interferogram into multiple phase‐correlated interferograms, is proposed to effectively enhance the sensitivity for cerebral capillary flow imaging. Both flow phantom and in vivo mouse brain imaging studies show that WDM‐ODT is able to significantly suppress background phase noise ...

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    2. Volumetric Doppler angle correction for ultrahigh-resolution optical coherence Doppler tomography

      Volumetric Doppler angle correction for ultrahigh-resolution optical coherence Doppler tomography

      Ultrahigh-resolution optical coherence Doppler tomography (μODT) demonstrates great potential for quantitative blood flow imaging owing to its large field of view and capillary resolution. However, μODT only detects the axial flow velocity and requires Doppler angle correction to retrieve the absolute velocity. Although methods for Doppler angle tracking of single or few large vessels have been reported, a method that enables angle correction of the entire 3D microvascular networks remains a challenge. Here, we present a method based on eigenvalue analysis of 3D Hessian matrix to retrieve the orientation of each tubular vessel. As the algorithm is voxel based, it ...

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    3. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF ...

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    4. Ultrasensitive quantification of 3D cerebral capillary blood flow network dynamics

      Ultrasensitive quantification of 3D cerebral capillary blood flow network dynamics

      Ultra-high resolution optical Doppler coherence tomography (μODT) is a promising tool for brain functional imaging. However, its sensitivity for detecting slow flows in capillary beds may limit its utility in visualizing and quantifying subtle changes in brain microcirculation. To address this limitation, we developed a novel method called contrast-enhanced μODT (c-μODT) in which intralipid is injected into mouse tail vein to enhance μODT detection sensitivity. We demonstrate that after intralipid injection, the flow detection sensitivity of μODT is dramatically enhanced by 230% as quantified by the fill factor (FF) of microvasculature. More importantly, we show that c-μODT preserves ...

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    5. Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo

      Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo

      Despite widespread applications of multiphoton microscopy in microcirculation, its small field of view and inability to instantaneously quantify cerebral blood flow velocity (CBFv) in vascular networks limit its utility in investigating the heterogeneous responses to brain stimulations. Optical Doppler tomography (ODT) provides 3D images of CBFv networks, but it suffers poor sensitivity for measuring capillary flows. Here we report on a new method, contrast-enhanced ODT with Intralipid that significantly improves quantitative CBFv imaging of capillary networks by obviating the errors from long latency between flowing red blood cells (low hematocrit ~ 20% in capillaries). This enhanced sensitivity allowed us to measure ...

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    6. Optical coherence Doppler tomography for quantitative cerebral blood flow imaging

      Optical coherence Doppler tomography for quantitative cerebral blood flow imaging

      Optical coherence Doppler tomography (ODT) is a promising neurotechnique that permits 3D imaging of the cerebral blood flow (CBF) network; however, quantitative CBF velocity (CBFv) imaging remains challenging. Here we present a simple phase summation method to enhance slow capillary flow detection sensitivity without sacrificing dynamic range for fast flow and vessel tracking to improve angle correction for absolute CBFv quantification. Flow phantom validation indicated that the CBFv quantification accuracy increased from 15% to 91% and the coefficient of variation (CV) decreased 9.3-fold;in vivo mouse brain validation showed that CV decreased 4.4-/10.8- fold for venular ...

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    7. Cerebral blood flow imaged with ultrahigh-resolution optical coherence angiography and Doppler tomography

      Cerebral blood flow imaged with ultrahigh-resolution optical coherence angiography and Doppler tomography

      Speckle contrast based optical coherence angiography (OCA) and optical coherence Doppler tomography (ODT) have been applied to image cerebral blood flow previously. However, the contrast mechanisms of these two methods are not fully studied. Here, we present both flow phantom and in vivo animal experiments using ultrahigh-resolution OCA (μOCA) and ODT (μODT) to investigate the flow sensitivity differences between these two methods. Our results show that the high sensitivity of μOCA for visualizing minute vasculature (e.g., slow capillary beds) is due to the enhancement by random Brownian motion of scatterers (e.g., red and white blood cells) within the ...

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    8. Characterization of dynamic physiology of the bladder by optical coherence tomography

      Characterization of dynamic physiology of the bladder by optical coherence tomography

      Because of its high spatial resolution and noninvasive imaging capabilities, optical coherence tomography has been used to characterize the morphological details of various biological tissues including urinary bladder and to diagnose their alternations (e.g., cancers). In addition to static morphology, the dynamic features of tissue morphology can provide important information that can be used to diagnose the physiological and functional characteristics of biological tissues. Here, we present the imaging studies based on optical coherence tomography to characterize motion related physiology and functions of rat bladder detrusor muscles and compared the results with traditional biomechanical measurements. Our results suggest that ...

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    9. Optical detection of brain function: simultaneous imaging of cerebral vascular response, tissue metabolism, and cellular activity in vivo

      Optical detection of brain function: simultaneous imaging of cerebral vascular response, tissue metabolism, and cellular activity in vivo

      It is known that a remaining challenge for functional brain imaging is to distinguish the coupling and decoupling effects among neuronal activity, cerebral metabolism, and vascular hemodynamics, which highlights the need for new tools to enable simultaneous measures of these three properties in vivo. Here, we review current neuroimaging techniques and their prospects and potential limitations for tackling this challenge. We then report a novel dual-wavelength laser speckle imaging (DW-LSI) tool developed in our labs that enables simultaneous imaging of cerebral blood flow (CBF), cerebral blood volume, and tissue hemoglobin oxygenation, which allows us to monitor neurovascular and tissue metabolic ...

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    10. Quantification of cocaine-induced cortical blood flow changes using laser speckle contrast imaging and Doppler optical coherence tomography

      Quantification of cocaine-induced cortical blood flow changes using laser speckle contrast imaging and Doppler optical coherence tomography

      We present a dual-imaging technique combining laser speckle contrast imaging and spectral-domain Doppler optical coherence tomography to enable quantitative characterization of local cerebral blood flow (CBF) changes in rat cortex in response to drug stimulus (e.g., cocaine) at high spatiotemporal resolutions. To examine the utility of this new technique, animal experiments were performed to study the influences of anesthetic regimes (e.g., isoflurane, α-chloralose) on the pharmadynamic effects of acute cocaine challenge. The results showed that cocaine-evoked CBF patterns (e.g., increases in α-chloralose and decreases in isoflurane regimes) were quantitatively characterized, thus rendering it a potentially useful tool ...

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    11. Enhancing Doppler Flow Imaging in Fourier-domain Optical Coherence Tomography

      Enhancing Doppler Flow Imaging in Fourier-domain Optical Coherence Tomography

      A digital frequency ramping method (DFRM) is proposed to improve the signal-to-noise ratio (SNR) of Doppler flow imaging in Fourier-domain optical coherence tomography (FDOCT). To examine the efficacy of DFRM for enhancing flow detection, computer simulation and tissue phantom study were conducted ... [Opt. Express 17, 3951-3963 (2009)]

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    12. Optical coherence Doppler tomography quantifies laser speckle contrast imaging for blood flow imaging in the rat cerebral cortex

      Optical coherence Doppler tomography quantifies laser speckle contrast imaging for blood flow imaging in the rat cerebral cortex

      A dual-imaging modality is demonstrated for high-resolution quantitative imaging of local cerebral blood flow in the rat cortex by combining simultaneous spectral-domain Doppler optical coherence tomography (SDOCT) and full-field laser speckle contrast imaging (LSCI). Preliminary studies in tissue flow phantom and cocaine-induced cerebral blood flow changes indicated that by correlating coregistered cortical arterial blood flow, the relative measurement of flow changes by LSCI could be accurately calibrated by the absolute flow imaging provided by SDOCT (least square fit, r2≈0.96). Quantitative LSCI of cerebral blood flow is crucial to the quantitative analyses of the spatiotemporal hemodynamics of functional brain ...

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    1-12 of 12
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  2. Topics in the News

    1. (12 articles) Congwu Du
    2. (12 articles) Yingtian Pan
    3. (11 articles) SUNY at Stony Brook
    4. (2 articles) Joseph A. Izatt
    5. (1 articles) National Institutes of Health
    6. (1 articles) James G. Fujimoto
    7. (1 articles) Valery V. Tuchin
    8. (1 articles) UC Davis
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    Optical coherence Doppler tomography quantifies laser speckle contrast imaging for blood flow imaging in the rat cerebral cortex Enhancing Doppler Flow Imaging in Fourier-domain Optical Coherence Tomography Quantification of cocaine-induced cortical blood flow changes using laser speckle contrast imaging and Doppler optical coherence tomography Optical detection of brain function: simultaneous imaging of cerebral vascular response, tissue metabolism, and cellular activity in vivo Characterization of dynamic physiology of the bladder by optical coherence tomography Cerebral blood flow imaged with ultrahigh-resolution optical coherence angiography and Doppler tomography Optical coherence Doppler tomography for quantitative cerebral blood flow imaging Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo Ultrasensitive quantification of 3D cerebral capillary blood flow network dynamics High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging Optoretinography: optical measurements of human cone and rod photoreceptor responses to light Nodular skin lesions: correlation of reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) features