1. 1-21 of 21
    1. DEVELOPMENT OF PHASE DECORRELATION OPTICAL COHERENCE TOMOGRAPHY FOR ASSESSMENT OF THE OCULAR LENS AND CORNEA

      DEVELOPMENT OF PHASE DECORRELATION OPTICAL COHERENCE TOMOGRAPHY FOR ASSESSMENT OF THE OCULAR LENS AND CORNEA

      The human ocular system is tightly maintained in order to sharply focus images onto the retina. Our understanding of the ocular system has benefited from the study of biomechanical phenomena. For instance, the field has begun to understand a range of diseases as biomechanical in origin – such as keratoconus, glaucoma, and myopia. This mechanical understanding of disease has led to the development of new treatments, primarily crosslinking, which directly address the mechanical deficiency and have generally proved to be highly effective. Keratoconus, which until recently could only be treated through contact lenses and corneal transplants, can now be treated relatively ...

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    2. Biophotonic Investigation of Cardiac Structure and Hemodynamics During Embryogenesis Using Optical Coherence Tomography (Thesis)

      Biophotonic Investigation of Cardiac Structure and Hemodynamics During Embryogenesis Using Optical Coherence Tomography (Thesis)

      Congenital heart disease/defects (CHDs) account for approximately one-third of all birth defects globally. Many of these will require invasive treatment within the first year of life, subsequent interventions, and a lifetime of monitoring. Alcohol has been known as a teratogen for several decades, and prenatal exposure alone is a significant cause of worldwide CHDs. Optical Coherence Tomography (OCT) has been used as an imaging modality for nearly three decades and is especially suited to the non-invasive imaging of small, semi-transparent tissue structures. Doppler OCT (DOCT) adds the ability to visualize and measure fluid flow and movement of reflective components ...

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    3. SPECTRAL CALIBRATION FOR SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BASED ON B-SCAN DOPPLER SHIFT WITH IN SITU. TISSUE IMAGES (Thesis)

      SPECTRAL CALIBRATION FOR SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BASED ON B-SCAN DOPPLER SHIFT WITH IN SITU. TISSUE IMAGES (Thesis)

      We propose a simple method of linearizing spectral interference fringes of spectral domain optical coherence tomography (SDOCT) 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 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, in situ. tissue images themselves can be used to linearize the wavenumber without requiring mirror images or additional ...

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    4. Title Automated Plaque Characterization of Intravascular Optical Coherence Tomography (IVOCT) Images Using 3D Cryo-image/Histology Validation (Thesis)

      Title Automated Plaque Characterization of Intravascular Optical Coherence Tomography (IVOCT) Images Using 3D Cryo-image/Histology Validation (Thesis)

      Intravascular optical coherence tomography (IVOCT) is a high-resolution (10-20 µm), high-contrast, catheter-based imaging technology that can identify major coronary plaques types (fibrous, lipid, and calcium). However, with >500 images generated in a single 2.5 second scan, automation is needed to facilitate live-time clinical use and off-line assessment of drug therapeutics. Therefore, we developed machine learning approaches for automated plaque characterization using cryo-imaging/histology for validation. However, we confronted a challenge in that IVOCT images are obtained perpendicular to the imaging catheter, while cryo-image volumes display the true 3D vessel geometry at a higher sampling rate. Our solution was to ...

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    5. Characterization and modeling of the human left atrium using optical coherence tomography (Thesis)

      Characterization and modeling of the human left atrium using optical coherence tomography (Thesis)

      With current needs to better understand the interaction between atrial tissue microstructure and atrial fibrillation dynamics, micrometer scale imaging with optical coherence tomography has significant potential to provide further insight on arrhythmia mechanisms and improve treatment guidance. However, optical coherence tomography imaging of cardiac tissue in humans is largely unexplored, and the ability of optical coherence tomography to identify the structural substrate of atrial fibrillation has not yet been investigated. Therefore, the objective of this thesis was to develop an optical coherence tomography imaging atlas of the human heart, study the utility of optical coherence tomography in providing useful features ...

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    6. OPTICAL COHERENCE TOMOGRAPHY TO MEASURE EFFECTS OF AUTOLOGOUS MESENCHYMAL STEM CELL TRANSPLANT IN MULTIPLE SCLEROSIS PATIENTS (Thesis)

      OPTICAL COHERENCE TOMOGRAPHY TO MEASURE EFFECTS OF AUTOLOGOUS MESENCHYMAL STEM CELL TRANSPLANT IN MULTIPLE SCLEROSIS PATIENTS (Thesis)

      Anterior visual pathway disease affects >50% of multiple sclerosis (MS) patients. Optical coherence tomography (OCT) monitors MS-related retinal degeneration. Retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thinning in MS correlates with clinical and visual disability, and brain atrophy. Mesenchymal stem cells (MSC) are immunomodulatory in MS animal models, targeting inflammatory CNS injury. A recent Cleveland Clinic phase 1 trial demonstrated feasibility/tolerability of autologous MSC transplant in MS patients. My study analyzed GCL and RNFL relationships with clinical, visual, and MRI measures, before and after MSC transplant. MSC transplant affected no differences from baseline to 6 months ...

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      Mentions: Cleveland Clinic
    7. AUTOMATED MACHINE LEARNING BASED ANALYSIS OF INTRAVASCULAR OPTICAL COHERENCE TOMOGRAPHY IMAGES (Thesis)

      AUTOMATED MACHINE LEARNING BASED ANALYSIS OF INTRAVASCULAR OPTICAL COHERENCE TOMOGRAPHY IMAGES (Thesis)

      Coronary artery disease (CAD) is the leading cause of death in the world. Most acute coronary events (e.g. heart attacks) are due to the rupture of atherosclerotic plaques inside the arteries, however, calcified lesion is the most widely treatable, typically, by stent implantation via percutaneous coronary intervention (PCI). Intravascular Optical Coherence Tomography (IVOCT) imaging has the resolution, contrast, and penetration depth to characterize coronary artery plaques. Conventional manual evaluation of IVOCT images, based on qualitative interpretation of image features, is tedious and time consuming. The aim of this PhD dissertation was to develop advanced algorithms to fully automate the ...

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    8. Development and Application of Optical Coherence Elastography for Corneal Biomechanics (Thesis)

      Development and Application of Optical Coherence Elastography for Corneal Biomechanics (Thesis)

      The biomechanical properties of the cornea are an important determinant of both the shape and function of the human visual system. Measuring the biomechanical properties on an in vivo basis requires the development of technologies not typically associated with mechanical measurement. Optical Coherence Elastography (OCE) is an optical based measurement capable of measuring micron level displacements in accessible tissues. The application of OCE to corneal measurement was made possible by the use of speckle tracking in the corneal stroma. Application of OCE to human donor corneas was used to measure the biomechanical properties of the human cornea in three separate ...

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    9. Investigating Hemodynamics of the Developing Embryonic Heart using Optical Coherence Tomography (Thesis)

      Investigating Hemodynamics of the Developing Embryonic Heart using Optical Coherence Tomography (Thesis)

      Blood flow is a critical factor that regulates developmental programs during cardiogenesis. During early embryonic development, deviations from the normal blood flow pattern have been shown to lead to congenital heart defects including septal defects and outflow tract anomalies. To better understand the role flow and the resulting hemodynamic forces play during cardiovascular development precise tools are needed to rapidly calculate and monitor these forces. Optical coherence tomography (OCT) is a noninvasive imaging modality that is well suited for imaging the developing heart due to its high spatial and temporal resolution. OCT is also capable of analyzing various cardiac functions ...

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    10. Machine Learning Based Analysis of Coronary Stent Images in Intravascular Optical Coherence Tomography Pullbacks (Thesis)

      Machine Learning Based Analysis of Coronary Stent Images in Intravascular Optical Coherence Tomography Pullbacks (Thesis)

      Coronary artery disease (CAD) is the most common heart disease and the leading cause of death worldwide. Stent implantation via percutaneous coronary intervention is a popular procedure for treating CAD. Drug eluting stents (DESs) were shown to reduce restenosis compared to bare metal stents. However, DESs were related to a higher risk of late stent thrombosis, a catastrophic clinical event caused by delayed arterial healing. Therefore, it’s important to evaluate the treatment efficacy and safety of new stent designs via pre-clinical and clinical trials. Stent strut coverage and apposition assessed by intravascular optical coherence tomography (IVOCT) have become important ...

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    11. Speckle Reduction in an All Fiber Time Domain Common Path Optical Coherence Tomography by Frame Averaging (Thesis)

      Speckle Reduction in an All Fiber Time Domain Common Path Optical Coherence Tomography by Frame Averaging (Thesis)

      Optical Coherence Tomography (OCT) is a non-invasive, high resolution morphological imaging modality which has gained significance since its inception in 1992 due to its diversified areas of tissue diagnostics in medical imaging. Time Domain OCT (TDOCT) is one of its simplest commercially viable systems. Image noise in TDOCT has been fundamentally attributed to speckle and most of the commercial algorithms that tackle image noise are predominantly hardware related or utilize complex statistical procedures. Simple frame averaging is a cost effective, post processing algorithm whose effects on TDOCT systems have not been evaluated and hence there was an unmet need forming ...

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    12. 3-D Volumetric Optical Coherence Tomography Imaging and Image Analysis of Barrett's Esophagus (Thesis)

      3-D Volumetric Optical Coherence Tomography Imaging and Image Analysis of Barrett's Esophagus (Thesis)
      Barrett's esophagus (BE) surveillance remains challenging, because even histopathology, the gold standard, is subject to sampling error. The esophageal mucosal area involved in BE can be 20 square centimeters or more. 3-D volumetric Imaging technology with high diagnostic accuracy may potentially guide and assist the standard histopathology, eliminate the sampling error and improve surveillance efficiency. It has been shown that endoscopic optical coherence tomography (EOCT) of a small mucosal area can obtain interpretable images of gastro-intestinal mucosal microstructure, differentiate mucosal types and detect dysplasia in Barrett’s esophagus. The realization of 3-D EOCT allows for further exploring the potential ...
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    13. Characterization of Cardiac Tissue Using Optical Coherence Tomography (Thesis)

      Characterization of Cardiac Tissue Using Optical Coherence Tomography (Thesis)
      Radiofrequency ablation (RFA) therapy is the standard of care for the treatment of cardiac arrhythmias. Current techniques to guide ablation therapy utilize low resolution two dimensional fluoroscopic images and functional measurements from the RFA catheter, temperature, impedance and electrograms. High resolution, depth resolved imaging is needed to characterize early structural changes in the myocardium due to disease and therapy. Optical coherence tomography (OCT) is a noninvasive imaging modality that provides high resolution, depth resolved imaging of tissue microstructure in real time. OCT provides subsurface imaging of depths 1-2 mm in cardiac tissue with high spatial resolution (~10 μm) in three ...
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    14. Validation of Optical Coherence Tomography-Based Crystalline Lens Thickness Measurements in Children (Thesis)

      Validation of Optical Coherence Tomography-Based Crystalline Lens Thickness Measurements in Children (Thesis)
      The purpose of this study was to evaluate the validity and repeatability of crystalline lens thickness measurements obtained by anterior segment optical coherence tomography (OCT). Optical coherence tomography utilizes infrared light and partial-coherence interferometry to produce a two-dimensional scan of the internal ocular structures in vivo. Changes in crystalline lens thickness are important to monitor for refractive error development, cataract progression, and anterior chamber alterations. Our goal was to develop an effective method of measuring the thickness of the crystalline lens with the Visante anterior segment OCT, to assess OCT repeatability, and to evaluate OCT validity as compared to A-scan ...
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    15. Anterior Segment Optical Coherence Tomography-Based Phakometry Measurements in Children (Thesis)

      Anterior Segment Optical Coherence Tomography-Based Phakometry Measurements in Children (Thesis)
      Anterior segment optical coherence tomography (AS-OCT) is emerging as a valuable tool for in vivo ocular biometry. This study constitutes the first known attempt at in vivo assessment of crystalline lens curvature using AS-OCT technology. METHODS: An ASOCT phakometry protocol was compared to video-based phakometry data on a sample of 42 children. RESULTS: AS-OCT phakometry demonstrated poor 95% limits of agreement (LOA) and significant magnitude bias, yielding excessively flat radii when used to measure flatter surfaces (anterior: P < 0.001, LOA = -8.82 to +6.52 mm; posterior: P < 0.001, LOA = -1.13 to +1.67 mm). Orthogonal regression-derived ...
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    16. Image Processing and Clinical Applications of Anterior Segment Optical Coherence Tomography (Thesis)

      Image Processing and Clinical Applications of Anterior Segment Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is an emerging imaging modality. It provides in vivo cross-sectional images with micron level resolution. OCT is attractive for imaging the anterior eye segment because of its characteristics on high resolution, non-contact, and easy anatomical interpretation. The fast data acquisition rate (>2000 axial scans per second) of current anterior segment OCT systems allows the measurement of corneal dimensions without significant motion error. It also generates huge amount of data. Manual anatomic reconstruction and measurement are time consuming and operator-dependent. Automated image processing and analysis techniques can overcome these limitations and make routine clinical use of OCT ...
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    17. A Study of Computer Vision and Pattern Recognition in Medical Image Analysis: Digital Microscopy and Optical Coherent Tomography (Thesis)

      A Study of Computer Vision and Pattern Recognition in Medical Image Analysis: Digital Microscopy and Optical Coherent Tomography (Thesis)
      Computer vision and pattern recognition techniques have been fostered to solve many practical problems of diverse areas. Medical image analysis using machine vision and learning intelligence is one of the most sought-after fields. Computer vision addresses problems of the use of computers to detect, partition, represent, group, track, and interpret crucial primitives from given visual inputs. By contrast, pattern recognition is the study of distinguishing and recognizing different patterns represented with quantitative measurements. As a result, both of these two components usually present themselves in medical image analysis research work. In this dissertation, two parts of new theoretical work and ...
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    18. Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)

      Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is an emerging optical technique based on low-coherence interferometry that provides noninvasive, subsurface, high-resolution imaging of biological microstructure. Endoscopic OCT (EOCT) differentiates the tissue layers of the gastrointestinal (GI) wall and can identify dysplasia in the mucosa. The objective of this research was the characterization of dysplasia in the GI tract, by EOCT in Barretts esophagus in the upper GI tract and by OCT in colonic crypts in the lower GI tract. Barretts esophagus (BE) and associated adenocarcinoma have emerged as a major health care problem over the last two decades. We developed computer-aided diagnosis (CAD ...
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    19. Ultra High Resolution and Contrast Sensitive Optical Coherence Tomography (Thesis)

      Ultra High Resolution and Contrast Sensitive Optical Coherence Tomography (Thesis)
      In this thesis, I first demonstrate three novel broad band light sources at above 1 µm for ultra-high resolution optical coherence tomography (OCT) based on multiple SLED combination and supercontinuum generation. The light sources are compact, reliable, smooth and ready for practical applications. The images achieved with those light sources showed superior quality in comparison to the images achieved under normal resolution OCT with axial resolution around 12 to 15 µm. In the second part of the thesis, the feasibility of using gold nanorod (NR) as a probe for contrast sensitive OCT is described. Two methods, photothermal effect (PT) and ...
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    20. Imaging the Embryonic Heart with Optical Coherence Tomography (Thesis)

      Imaging the Embryonic Heart with Optical Coherence Tomography (Thesis)
      Abnormalities that occur during cardiac looping in the early embryo are responsible for congenital heart disease. To date researchers have had to rely upon bioassays, video microscopy and mathematical models to investigate the mechanisms underlying development during looping. Direct observation of looping has been problematic due to the diminutive size (< 2 mm) of the heart and the inability to measure the small and rapid events that influence heart development. Optical coherence tomography (OCT) is a noninvasive imaging tool with the spatiotemporal resolution and field of view to observe both structure and function during the critical time period of looping. Here ...
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    21. Optical Coherence Tomography For The Screening of Donor Corneas and Examination of the Retinal Nerve Fiber Directional Reflectance (Thesis)

      Optical Coherence Tomography For The Screening of Donor Corneas and Examination of the Retinal Nerve Fiber Directional Reflectance (Thesis)
      Optical coherence tomography (OCT) is a high resolution, non-invasive imaging technology that employs light to create detailed images of the body. In medicine, OCT is most widely used in ophthalmology to create high resolution images of the cornea and the retina. The group index of cornea, rather than phase refractive index, is required for thickness calculations with optical coherence tomography (OCT). Recent advances with high speed OCT at 1.3 m make index measurement at this wavelength of great interest. Group indices of 3 human eye bank corneas were measured in vitro using optical low-coherence reflectometry. Measurements were made in ...
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    1-21 of 21
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