1. Articles from Hui Wang

    1-24 of 30 1 2 »
    1. Insight into the fundamental trade-offs of diffusion MRI from polarization-sensitive optical coherence tomography in ex vivo human brain

      Insight into the fundamental trade-offs of diffusion MRI from polarization-sensitive optical coherence tomography in ex vivo human brain

      In the first study comparing high angular resolution diffusion MRI (dMRI) in the human brain to axonal orientation measurements from polarization-sensitive optical coherence tomography (PSOCT), we compare the accuracy of orientation estimates from various dMRI sampling schemes and reconstruction methods. We find that, if the reconstruction approach is chosen carefully, single-shell dMRI data can yield the same accuracy as multi-shell data, and only moderately lower accuracy than a full Cartesian-grid sampling scheme. Our results suggest that current dMRI reconstruction approaches do not benefit substantially from ultra-high b-values or from very large numbers of diffusion-encoding directions. We also show that accuracy ...

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    2. Spectral calibration for spectral domain optical coherence tomography based on B-scan Doppler shift with tissue images

      Spectral calibration for spectral domain optical coherence tomography based on B-scan Doppler shift with tissue images

      Abstract: We propose a simple method of linearizing spectral interference fringes of spectral domain optical coherence tomography (SD-OCT) based on B-scan Doppler frequency shift (DFS), which can be obtained by offsetting the laser beam from the pivot of a scanning mirror. We show that DFS is proportional to wavenumber. A DFS based calibration curve can be then extracted from either a single mirror image or multiple tissue images. By examining the convergence of the nonlinear coefficients of the DFS curve fitted with a polynomial equation, tissue images themselves can be used to linearize the wavenumber without requiring mirror images or ...

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      Mentions: Hui Wang
    3. Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 2. Impacts of optic nerve head parameters

      Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 2. Impacts of optic nerve head parameters

      Clinicians use retinal nerve fiber layer thickness (RNFLT) measured by optical coherence tomography (OCT) as an adjunct to glaucoma diagnosis. Ametropia is accompanied by changes to the optic nerve head (ONH), which may affect how OCT machines mark RNFLT measurements as abnormal. These changes in abnormality patterns may bias glaucoma diagnosis. Here, we investigate the relationship between OCT abnormality patterns and the following ONH-related and ametropia-associated parameters on 421 eyes of glaucoma patients: optic disc tilt and torsion, central retinal vessel trunk location (CRVTL), and nasal and temporal retinal curvature adjacent to ONH, quantified as nasal/temporal slopes of the ...

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    4. Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 1. Impacts of refractive error and interartery angle

      Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 1. Impacts of refractive error and interartery angle

      Retinal nerve fiber layer thickness (RNFLT) measured by optical coherence tomography (OCT) is widely used in clinical practice to support glaucoma diagnosis. Clinicians frequently interpret peripapillary RNFLT areas marked as abnormal by OCT machines. However, presently, clinical OCT machines do not take individual retinal anatomy variation into account, and according diagnostic biases have been shown particularly for patients with ametropia. The angle between the two major temporal retinal arteries (interartery angle, IAA) is considered a fundamental retinal ametropia marker. Here, we analyze peripapillary spectral domain OCT RNFLT scans of 691 glaucoma patients and apply multivariate logistic regression to quantitatively compare ...

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    5. Characterizing the optical properties of human brain tissue with high numerical aperture optical coherence tomography

      Characterizing the optical properties of human brain tissue with high numerical aperture optical coherence tomography

      Quantification of tissue optical properties with optical coherence tomography (OCT) has proven to be useful in evaluating structural characteristics and pathological changes. Previous studies primarily used an exponential model to analyze low numerical aperture (NA) OCT measurements and obtain the total attenuation coefficient for biological tissue. In this study, we develop a systematic method that includes the confocal parameter for modeling the depth profiles of high NA OCT, when the confocal parameter cannot be ignored. This approach enables us to quantify tissue optical properties with higher lateral resolution. The model parameter predictions for the scattering coefficients were tested with calibrated ...

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    6. Impact of anatomical parameters on optical coherence tomography retinal nerve fiber layer thickness abnormality patterns

      Impact of anatomical parameters on optical coherence tomography retinal nerve fiber layer thickness abnormality patterns

      Purpose: To evaluate the effects of four anatomical parameters (angle between superior and inferior temporal retinal arteries [inter-artery angle, IAA], optic disc [OD] rotation, retinal curvature, and central retinal vessel trunk entry point location [CRVTL]) on retinal nerve fiber layer thickness (RNFLT) abnormality marks by OCT machines. Methods: Cirrus OCT circumpapillary RNFLT measurements and Humphrey visual fields (HVF 24-2) of 421 patients from a large glaucoma clinic were included. Ellipses were fitted to the OD borders. Ellipse rotation relative to the vertical axis defined OD rotation. CRVTL was manually marked on the horizontal axis of the ellipse on the OCT ...

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    7. Polarization-sensitive optical coherence tomography of the human brain connectome

      Polarization-sensitive optical coherence tomography of the human brain connectome

      The human brain is composed of approximately 100 billion neurons that ‘communicate’ through an intricate network of axons and dendrites. 1 The difficulty of tracing these 3D neuronal pathways, however, has been a critical barrier for standard histology (the study of microscopic anatomy) over the past 100 years. Indeed, there is still no technology that can be used to acquire microscopic images in undistorted 3D space for mapping human brain connectivity. Currently available techniques for 3D brain mapping include histological staining and polarized light imaging. 2, 3 In these approaches, 2D image slices are obtained, but these must be physically ...

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    8. Impact of temporal resolution on estimating capillary RBC-flux with optical coherence tomography

      Impact of temporal resolution on estimating capillary RBC-flux with optical coherence tomography

       Optical coherence tomography (OCT) has been used to measure capillary red blood cell (RBC) flux. However, one important technical issue is that the accuracy of this method is subject to the temporal resolution (ΔtΔt) of the repeated RBC-passage B-scans. A ceiling effect arises due to an insufficient ΔtΔt limiting the maximum RBC-flux that can be measured. In this letter, we first present simulations demonstrating that Δt=1.5  msΔt=1.5  mspermits measuring RBC-flux up to 150  RBCs/s150  RBCs/s with an underestimation of 9%. The simulations further show that measurements with Δt=3 ...

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    9. Quantifying three-dimensional optic axis using polarization-sensitive optical coherence tomography

      Quantifying three-dimensional optic axis using polarization-sensitive optical coherence tomography

      The optic axis of birefringent samples indicates the direction of optical anisotropy, which should be described in three-dimensional (3-D) space. We present a method to quantify the complete 3-D optic axis orientation calculated from in-plane optic axis measurements from a polarization-sensitive optical coherence tomography system. The in-plane axis orientations with different illumination angles allow the calculation of the necessary polar angle. The method then provides the information to produce the actual birefringence. The method and results from a biological sample are presented.

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    10. Polarization sensitive optical coherence microscopy for brain imaging

      Polarization sensitive optical coherence microscopy for brain imaging

      Optical coherence tomography (OCT) and optical coherence microscopy (OCM) have demonstrated the ability to investigate cyto- and myelo-architecture in the brain. Polarization-sensitive OCT provides sensitivity to additional contrast mechanisms, specifically the birefringence of myelination and, therefore, is advantageous for investigating white matter fiber tracts. In this Letter, we developed a polarization-sensitive optical coherence microscope (PS-OCM) with a 3.5 μm axial and 1.3 μm transverse resolution to investigate fiber organization and orientation at a finer scale than previously demonstrated with PS-OCT. In a reconstructed mouse brain section, we showed that at the focal depths of 20–70 μm, the ...

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    11. Multi-contrast optical coherence tomography for brain imaging and mapping (Thesis)

      Multi-contrast optical coherence tomography for brain imaging and mapping (Thesis)

      Although our knowledge of neuronal function and regional activity has been tremendously enriched in the past decades, coordination of these neurons to form the complex behaviors has yet to be understood. The neuronal pathways (also named connectome) form the structural foundation of the dynamic circuits in the brain. The recent interests in connectome and brainwide database have imposed a pressing need for high-resolution imaging techniques that allows large coverage. This dissertation develops a novel multi-contrast optical coherence tomography (MC-OCT) technique for the application of brainwide imaging and architectural mapping in 3D at high spatiotemporal resolution, with an emphasis on the ...

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    12. Fiber-optic catheter-based polarization-sensitive OCT for radio-frequency ablation monitoring

      Fiber-optic catheter-based polarization-sensitive OCT for radio-frequency ablation monitoring

      An all-fiber optic catheter-based polarization-sensitive optical coherence tomography system is demonstrated. A novel multiplexing method was used to illuminate the sample, splitting the light from a 58.5 kHz Fourier-domain mode-locked laser such that two different polarization states, alternated in time, are generated by two semiconductor optical amplifiers. A 2.3 mm forward-view cone-scanning catheter probe was designed, fabricated, and used to acquire sample scattering intensity and phase retardation images. The system was first verified with a quarter-wave plate and then by obtaining intensity and phase retardation images of high-birefringence plastic, human skin in vivo , and untreated and thermally ablated ...

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    13. Cross-validation of serial optical coherence scanning and diffusion tensor imaging: A study on neural fiber maps in human medulla oblongata

      Cross-validation of serial optical coherence scanning and diffusion tensor imaging: A study on neural fiber maps in human medulla oblongata

      We established a strategy to perform cross-validation of serial optical coherence scanner imaging (SOCS) and diffusion tensor imaging (DTI) on a postmortem human medulla. Following DTI, the sample was serially scanned by SOCS, which integrates a vibratome slicer and a multi-contrast optical coherence tomography rig for large-scale three-dimensional imaging at microscopic resolution. The DTI dataset was registered to the SOCS space. An average correlation coefficient of 0.9 was found between the co-registered fiber maps constructed by fractional anisotropy and retardance contrasts. Pixelwise comparison of fiber orientations demonstrated good agreement between the DTI and SOCS measures. Details of the comparison ...

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    14. Serial optical coherence scanner for large-scale brain imaging at microscopic resolution

      Serial optical coherence scanner for large-scale brain imaging at microscopic resolution

      We describe a serial optical coherence scanner (SOCS) for high resolution imaging of ex-vivo brain. SOCS integrates a multi-contrast optical coherence tomography and a vibratome slicer to establish comprehensive brain anatomy and fiber pathways in three-dimensional space. Rat brain images are demonstrated by utilizing intrinsic optical contrasts including back-scattering, birefringence and optic axis orientation, which are simultaneously generated from the same dataset. Volumetric images from serial scans are combined to realize large scale brain maps. Nerve fiber tracts are globally described in 3D by retardance, and delicately delineated by cross-polarization at the resolution of 15 × 15 × 5.5 μm 3 ...

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    15. In vivo intracardiac OCT imaging through percutaneous access: Towards image guided radio-frequency ablation

      In vivo intracardiac OCT imaging through percutaneous access: Towards image guided radio-frequency ablation

      BACKGROUND Complete catheter-tissue contact and permanent tissue destruction are essential for efficient radio-frequency ablation (RFA) during cardiac arrhythmia treatment. Current methods of monitoring lesion formation are indirect and unreliable. We aim to develop optical coherence tomography (OCT) as an imaging guidance for RFA. OBJECTIVES The purpose of this study is to evaluate the feasibility of using OCT catheter to image endocardia wall in active beating hearts through percutaneous access. This is a critical step toward image guided RFA in a clinic setting. METHODS A cone-scanning forward-viewing OCT catheter was advanced into active beating hearts through percutaneous access in four swine ...

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    16. In vivo intracardiac optical coherence tomography imaging through percutaneous access: toward image-guided radio-frequency ablation

      In vivo intracardiac optical coherence tomography imaging through percutaneous access: toward image-guided radio-frequency ablation
      Complete catheter-tissue contact and permanent tissue destruction are essential for efficient radio-frequency ablation (RFA) during cardiac arrhythmia treatment. Current methods of monitoring lesion formation are indirect and unreliable. The purpose of this study is to evaluate the feasibility of using optical coherence tomography (OCT) catheter to image endocardial wall in actively beating hearts through percutaneous access. We reported the first in vivo intracardiac OCT imaging through percutaneous access with a thin and flexible OCT catheter. This is a critical step toward image-guided RFA in a clinical setting. A cone-scanning forward-viewing OCT catheter was advanced into beating hearts through percutaneous access ...
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    17. Motion artifacts associated with in vivo endoscopic OCT images of the esophagus

      Motion artifacts associated with in vivo endoscopic OCT images of the esophagus
      3-D optical coherence tomography (OCT) has been extensively investigated as a potential screening and/or surveillance tool for Barrett’s esophagus (BE). Understanding and correcting motion artifact may improve image interpretation. In this work, the motion trace was analyzed to show the physiological origin (respiration and heart beat) of the artifacts. Results showed that increasing balloon pressure did not sufficiently suppress the physiological motion artifact. An automated registration algorithm was designed to correct such artifacts. The performance of the algorithm was evaluated in images of normal porcine esophagus and demonstrated in images of BE in human patients.
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    18. Using optical coherence tomography for the longitudinal non-invasive evaluation of epidermal thickness in a murine model of chronic skin inflammation

      Using optical coherence tomography for the longitudinal non-invasive evaluation of epidermal thickness in a murine model of chronic skin inflammation
      Background Non-invasive methods are desirable for longitudinal studies examining drug efficacy and disease resolution defined as decreases in epidermal thickness in mouse models of psoriasiform skin disease. This would eliminate the need for either sacrificing animals or collecting serial skin biopsies to evaluate changes in disease progression during an individual study. The quantitation of epidermal thickness using optical coherence tomography (OCT) provides an alternative to traditional histology techniques. Methods Using the KC-Tie2 doxycycline-repressible psoriasiform skin disease mouse model, OCT imaging was completed on diseased back skin of adult KC-Tie2 (n = 3–4) and control (n = 3–4) mice, followed immediately ...
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    19. Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography

      Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography
      Comprehensive understanding of connective neural pathways in the brain has put great challenges on the current imaging techniques, for which three-dimensional (3D) visualization of fiber tracts with high spatiotemporal resolution is desirable. Here we present optical imaging and tractography of rat brain ex-vivo using multi-contrast optical coherence tomography (MC-OCT), which is capable of simultaneously generating depth-resolved images of reflectivity, phase retardance, optic axis orientation and, for in-vivo studies, blood flow images. Using the birefringence property of myelin sheath, nerve fiber tracts as small as a few tens of micrometers can be resolved and neighboring fiber tracts with different orientations can ...
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    20. The impact of an eccentric intravascular ImageWire during coronary optical coherence tomography imaging

      The impact of an eccentric intravascular ImageWire during coronary optical coherence tomography imaging
      Optical Coherence Tomography (OCT) provides high-resolution imaging which enables characterisation of atherosclerosis and vascular response to injury, but to ensure optimal analysis, one must realise potential sources of image distortion. We designed a series of analysesl, using coronary stents as a model, to investigate the influence of wire position on OCT-derived vascular images.
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    21. Three-Dimensional Imaging of Ureter With Endoscopic Optical Coherence Tomography

      Three-Dimensional Imaging of Ureter With Endoscopic Optical Coherence Tomography
      Objectives To verify the ability to identify the layered structures of the ureteral wall and to image a segment of the ureter in 3 dimensions with high-speed, endoscopic optical coherence tomography (EOCT). Methods We imaged a porcine ureter ex vivo using a spectral-domain EOCT with a specially designed circumferential scanning fiber catheter. The images were correlated with the histologic findings to identify the corresponding structures. Three-dimensional images and en face images at different depths from the luminal surface were reconstructed from the multiple cross-sectional images to visualize the layered structure of a segment of the ureter from different perspectives. Results ...
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    22. Semiautomatic segmentation and quantification of calcified plaques in intracoronary optical coherence tomography images

      Semiautomatic segmentation and quantification of calcified plaques in intracoronary optical coherence tomography images
      Coronary calcified plaque (CP) is both an important marker of atherosclerosis and major determinant of the success of coronary stenting. Intracoronary optical coherence tomography (OCT) with high spatial resolution can provide detailed volumetric characterization of CP. We present a semiautomatic method for segmentation and quantification of CP in OCT images. Following segmentation of the lumen, guide wire, and arterial wall, the CP was localized by edge detection and traced using a combined intensity and gradient-based level-set model. From the segmentation regions, quantification of the depth, area, angle fill fraction, and thickness of the CP was demonstrated. Validation by comparing the ...
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    23. Endoscopically guided spectral-domain OCT with double-balloon catheters

      Endoscopically guided spectral-domain OCT with double-balloon catheters
      Fourier-domain optical coherence tomography (OCT) and balloon-based catheters have furthered the potential of OCT as a real-time surveillance tool for Barrett’s esophagus (BE). However, a balloon catheter, which expands the esophagus and centers the catheter, applies direct pressure on the esophagus. This may affect the tissue appearance and the ability to detect dysplasia in BE. To study this effect, we propose a double-balloon catheter to allow imaging with and without balloon-tissue contact. A system design based on a spectral-domain OCT platform is reported and validated by acquisition of high quality, volumetric images of swine esophagus in vivo.
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    24. Real-time monitoring of cardiac radio-frequency ablation lesion formation using an optical coherence tomography forward-imaging catheter

      Real-time monitoring of cardiac radio-frequency ablation lesion formation using an optical coherence tomography forward-imaging catheter
      Radio-frequency ablation (rfa) is the standard of care for the treatment of cardiac arrhythmias; however, there are no direct measures of the successful delivery of ablation lesions. Optical coherence tomography (OCT) imaging has the potential to provide real-time monitoring of cardiac rfa therapy, visualizing lesion formation and assessing tissue contact in the presence of blood. A rfa-compatible forward-imaging conical scanning probe is prototyped to meet this need. The forward-imaging probe provides circular scanning, with a 2-mm scan diameter and 30-µm spot size. During the application of rf energy, dynamics are recorded at 20 frames per second with a 40-kHz A-line ...
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    1-24 of 30 1 2 »
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    1. (28 articles) Hui Wang
    2. (15 articles) Case Western Reserve University
    3. (15 articles) Andrew M. Rollins
    4. (9 articles) Harvard University
    5. (7 articles) Taner Akkin
    6. (6 articles) David A. Boas
    7. (5 articles) University of Minnesota
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    9. (5 articles) Wei Kang
    10. (3 articles) Michael W. Jenkins
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    13. (1 articles) Université Pierre et Marie Curie
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    Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain In vitro characterization of cardiac radiofrequency ablation lesions using optical coherence tomography Real-time monitoring of cardiac radio-frequency ablation lesion formation using an optical coherence tomography forward-imaging catheter Endoscopically guided spectral-domain OCT with double-balloon catheters Semiautomatic segmentation and quantification of calcified plaques in intracoronary optical coherence tomography images Three-Dimensional Imaging of Ureter With Endoscopic Optical Coherence Tomography The impact of an eccentric intravascular ImageWire during coronary optical coherence tomography imaging Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography Changes in the Retinal Microvasculature Measured Using Optical Coherence Tomography Angiography According to Age Direct en-face, speckle-reduced images using angular-compounded Master-Slave optical coherence tomography A case report of a recurrent early and late Bioresorbable vascular scaffold thrombosis: serial angiography and optical coherence tomography findings Optical coherence tomography angiography as a novel approach to contactless evaluation of sublingual microcirculation: A proof of principle study