1. Articles from Yuandong Li

    1-13 of 13
    1. Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Cerebral ischemic stroke causes injury to brain tissue characterized by a complex cascade of neuronal and vascular events. Imaging during early stages of its development allows prediction of tissue infarction and penumbra, so that optimal intervention can be determined in order to salvage brain function impairment. Therefore, there is a critical need for novel imaging techniques that can characterize brain injury in the earliest phases of ischemic stroke. This study examined optical coherence tomography (OCT) for imaging acute injury in experimental ischemic stroke in vivo. Based on endogenous optical scattering signals provided by OCT imaging, we have developed a single ...

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    2. Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Penetrating vessels bridge the mesh of communicating vessels on the surface of the cortex with the subsurface microvascular beds that feed the underlying neural tissue. Their accurate identification in vivo is important in the investigations of neural degenerative diseases, e.g., Alzheimer's disease and stroke. Here, we propose an efficient method to automatically map cortical penetrating vessels based on an eigen decompensation analysis of the optical coherence tomography (OCT) and OCT angiographic signals. We first project the ensemble of repeated OCT signals into a feature space that represents the power spectral components of eigenvectors through a well-known eigen-decomposition method ...

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    3. A non‐invasive imaging and measurement using optical coherence tomography angiography for the assessment of gingiva: An in vivo study

      A non‐invasive imaging and measurement using optical coherence tomography angiography for the assessment of gingiva: An in vivo study

      Gingiva is the soft tissue that surrounds and protects the teeth. Healthy gingiva provides an effective barrier to periodontal insults to deeper tissue, thus is an important indicator to a patient’s periodontal health. Current methods in assessing gingival tissue health, including visual observation and physical examination with probing on the gingiva, are qualitative and subjective. They may become cumbersome when more complex cases are involved, such as variations in gingival biotypes where feature and thickness of the gingiva are considered. A non‐invasive imaging technique providing depth‐resolved structural and vascular information is necessary for an improved assessment of ...

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    4. Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography

      Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography

      Capillary velocity increases by 21% and velocity heterogeneity increases by 19% with older age. Abstract Normal aging is associated with significant alterations in brain’s vascular structure and function, which can lead to compromised cerebral circulation and increased risk of neurodegeneration. The in vivo examination of cerebral blood flow (CBF), including capillary beds, in aging brains with sufficient spatial detail remains challenging with current imaging modalities. In the present study, we use three-dimensional (3-D) quantitative optical coherence tomography angiography (OCTA) to examine characteristic differences of the cerebral vasculatures and hemodynamics at the somatosensory cortex (S1) between old (16-month-old) and young ...

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    5. Optical coherence tomography angiography monitors human cutaneous wound healing over time

      Optical coherence tomography angiography monitors human cutaneous wound healing over time

      Background: In vivo imaging of the complex cascade of events known to be pivotal elements in the healing of cutaneous wounds is a difficult but essential task. Current techniques are highly invasive, or lack the level of vascular and structural detail required for accurate evaluation, monitoring and treatment. We aimed to use an advanced optical coherence tomography (OCT)-based angiography (OCTA) technique for the non-invasive, high resolution imaging of cutaneous wound healing. Methods: We used a clinical prototype OCTA to image, identify and track key vascular and structural adaptations known to occur throughout the healing process. Specific vascular parameters, such ...

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    6. Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions

      Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions

      Background In clinical dermatology, the identification of subsurface vascular and structural features known to be associated with numerous cutaneous pathologies remains challenging without the use of invasive diagnostic tools. Objective To present an advanced optical coherence tomography angiography (OCTA) method to directly visualize capillary-level vascular and structural features within skin in vivo . Methods An advanced OCTA system with a 1310 nm wavelength was used to image the microvascular and structural features of various skin conditions. Subjects were enrolled and OCTA imaging was performed with a field of view of approximately 10 × 10 mm. Skin blood flow was identified using an ...

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    7. Optical coherence tomography angiography-based capillary velocimetry

      Optical coherence tomography angiography-based capillary velocimetry

      Challenge persists in the field of optical coherence tomography (OCT) when it is required to quantify capillary blood flow within tissue beds in vivo . We propose a useful approach to statistically estimate the mean capillary flow velocity using a model-based statistical method of eigendecomposition (ED) analysis of the complex OCT signals obtained with the OCT angiography (OCTA) scanning protocol. ED-based analysis is achieved by the covariance matrix of the ensemble complex OCT signals, upon which the eigenvalues and eigenvectors that represent the subsets of the signal makeup are calculated. From this analysis, the signals due to moving particles can be ...

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    8. Cerebral capillary velocimetry based on temporal OCT speckle contrast

      Cerebral capillary velocimetry based on temporal OCT speckle contrast

      We propose a new optical coherence tomography (OCT) based method to measure red blood cell (RBC) velocities of single capillaries in the cortex of rodent brain. This OCT capillary velocimetry exploits quantitative laser speckle contrast analysis to estimate speckle decorrelation rate from the measured temporal OCT speckle signals, which is related to microcirculatory flow velocity. We hypothesize that OCT signal due to sub-surface capillary flow can be treated as the speckle signal in the single scattering regime and thus its time scale of speckle fluctuations can be subjected to single scattering laser speckle contrast analysis to derive characteristic decorrelation time ...

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    9. Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo

      Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo

      Purpose : To perform an analysis of optical coherence tomography (OCT) abnormalities in patients with MEWDS, during the acute and recovery stages, using enhanced depth imaging-OCT (EDI-OCT). Methods : A retrospective case series of five patients with MEWDS was included. EDI-OCT imaging was evaluated to detect retinal and choroidal features. Results : In the acute phase, focal impairment of the ellipsoid zone and external limiting membrane, hyperreflective dots in the inner choroid, and full-thickness increase of the choroidal profile were observed in the affected eye; disappearance of these findings and restoration of the choroidal thickness ( p = 0.046) was appreciated in the recovery ...

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    10. Tail artifact removal in OCT angiography images of rodent cortex

      Tail artifact removal in OCT angiography images of rodent cortex

      Optical coherence tomography angiography (OCTA) is a surging non-invasive, label-free, in vivo volumetric imaging method, currently being translated to clinical ophthalmology and becoming popular in neuroscience. Despite its attractiveness, there is an inherent issue of using OCT angiograms for quantitative cerebrovascular studies: The dynamic scattering of moving erythrocytes within pial vasculature creates tail-like artifacts that shadow the capillary vessels in the deeper layers of cortex. This false flow effect is relatively benign for qualitative visualization purposes, but it might have a significant impact on quantitative interpretation of angiographic results. In this work, we propose a simple image processing method to ...

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    11. In vivo tissue injury mapping using optical coherence tomography based methods

      In vivo tissue injury mapping using optical coherence tomography based methods

      An injury causes changes in the optical attenuation coefficient (OAC) of a light beam traveling inside a tissue. We report a method called tissue injury mapping (TIM), which utilizes a noninvasive in vivo optical coherence tomography approach to generate an OAC and microvascular map of the injured tissue. Using TIM, the infarct region development in a mouse cerebral cortex during a stroke is visualized. Moreover, we demonstrate the changes in human facial skin structure and microvasculature during an acne lesion development from initiation to scarring. The results indicate that TIM may be used to aid in the characterization and the ...

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    12. Vasodynamics of pial and penetrating arterioles in relation to arteriolo-arteriolar anastomosis after focal stroke

      Vasodynamics of pial and penetrating arterioles in relation to arteriolo-arteriolar anastomosis after focal stroke

      Changes in blood perfusion in highly interconnected pial arterioles provide important insights about the vascular response to ischemia within brain. The functional role of arteriolo-arteriolar anastomosis (AAA) in regulating blood perfusion through penetrating arterioles is yet to be discovered. We apply a label-free optical microangiography (OMAG) technique to evaluate the changes in vessel lumen diameter and red blood cell velocity among a large number of pial and penetrating arterioles within AAA abundant region overlaying the penumbra in the parietal cortex after a middle cerebral artery occlusion (MCAO). In comparison with two-photon microscopy, the OMAG technique makes it possible to image ...

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    13. High resolution imaging of acne lesion development and scarring in human facial skin using OCT-based microangiography

      High resolution imaging of acne lesion development and scarring in human facial skin using OCT-based microangiography

      Background and Objective Acne is a common skin disease that often leads to scarring. Collagen and other tissue damage from the inflammation of acne give rise to permanent skin texture and microvascular changes. In this study, we demonstrate the capabilities of optical coherence tomography-based microangiography in detecting high-resolution, three-dimensional structural, and microvascular features of in vivo human facial skin during acne lesion initiation and scar development. Materials and Methods A real time swept source optical coherence tomography system is used in this study to acquire volumetric images of human skin. The system operates on a central wavelength of 1,310 ...

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    1-13 of 13
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  2. Topics in the News

    1. (13 articles) University of Washington
    2. (13 articles) Ruikang K. Wang
    3. (6 articles) Woo June Choi
    4. (1 articles) UCSF
    5. (1 articles) National Institutes of Health
    6. (1 articles) Tokyo Medical & Dental University
    7. (1 articles) Oregon Health & Science University
    8. (1 articles) Alireza Sadr
    9. (1 articles) Hrebesh M. Subhash
    10. (1 articles) Indiana University
    11. (1 articles) Donald T. Miller
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    High resolution imaging of acne lesion development and scarring in human facial skin using OCT-based microangiography Vasodynamics of pial and penetrating arterioles in relation to arteriolo-arteriolar anastomosis after focal stroke In vivo tissue injury mapping using optical coherence tomography based methods Tail artifact removal in OCT angiography images of rodent cortex Optical coherence tomography based microangiography provides an ability to longitudinally image arteriogenesis in vivo Cerebral capillary velocimetry based on temporal OCT speckle contrast Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions Optical coherence tomography angiography monitors human cutaneous wound healing over time A non‐invasive imaging and measurement using optical coherence tomography angiography for the assessment of gingiva: An in vivo study Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia Research Associate / Postdoctoral Fellow in Adaptive Optics and Optical Coherence Tomography at Indiana University Spectral interferogram prediction in high resolution dual- and multiple-band Fourier domain optical coherence tomography