1. Articles in category: Student Theses

    1-24 of 129 1 2 3 4 5 6 »
    1. 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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    2. Investigation of low coherence interferometry techniques for biomedical applications (Thesis)

      Investigation of low coherence interferometry techniques for biomedical applications (Thesis)

      Interferometric techniques have been used as imaging techniques in many applications. In using low coherence sources in interferometry, good axial resolution can be achieved. The objective of this thesis is to investigate the use low coherence interferometry in biomedical applications. Low coherence interferometry (LCI) was incorporated into an optical tweezers system to determine the trapping dynamics. An optical coherence tomography (OCT) system based on LCI principles was designed and implemented to detect virus infection in orchid leaves. The OCT system was then modified to realize a high-speed endoscopic OCT imaging system. A numerical method and a common-path probe design were ...

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    3. Investigation of the normal and pathological development of the macula of the infant human eye using high resolution Optical Coherence Tomography (Thesis)

      Investigation of the normal and pathological development of the macula of the infant human eye using high resolution Optical Coherence Tomography (Thesis)

      The fovea is a specialised retinal area responsible for high spatial vision. Development of the fovea involves centrifugal migration of inner retinal layers (IRLs) away from the fovea and centripetal displacement of the cone photoreceptors into the fovea and is thought to be complete by 5 years of age. Current understanding of human foveal development is limited to studies of few histological specimens. The recent development of hand-held spectral domain optical coherence tomography (HHSDOCT), can overcome this limitation by facilitating large scale in vivo imaging of the infant human retina, both in controls and in conditions such as achromatopsia and ...

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    4. Optical Coherence Tomography for Material Characterization (Thesis)

      Optical Coherence Tomography for Material Characterization (Thesis)

      Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics, while OCT in the non-destructive testing (NDT) field is lagging far behind. The aim of this thesis is to use OCT as a novel NDT technique for material structure characterization and damage detection. Besides an overview of the OCT fundamentals and developments, the thesis is mainly driven by three tasks: instrument design, signal processing, and applications. An ...

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    5. Automatic quantification of intravascular optical coherence tomography (Thesis)

      Automatic quantification of intravascular optical coherence tomography (Thesis)

      As mentioned above, IVOCT, as a novel imaging modality, has played an active role in a wide range of CAD applications, including research and clinical routine. Due to its unparalleled high resolution and the ability to delineate complex vascular structures, IVOCT technology makes many precise measurement and novel applications possible. However, currently, a lot of analyses in IVOCT images are still relying on the manual work which decreases their value. The goal of this thesis is to develop robust and accurate (semi)automated methods that can detect and segment the interesting components in IVOCT pullback runs, such as implanted stent ...

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    6. 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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    7. Statistical estimation of haemodynamic parameters in optical coherence tomography (Thesis)

      Statistical estimation of haemodynamic parameters in optical coherence tomography (Thesis)

      Optical coherence tomography (OCT) is an imaging modality analogous to ultrasound. By using the interference properties of light, one may image to micrometer resolutions using interferometric methods. Most modern systems can acquire A-scans at kHz to MHz speeds, and are capable of real-time 3D imaging. OCT has been used extensively in ophthalmology and has been used in angiography to quantify blood flow. The aim of this research has been to develop statistically optimal estimators for blood flow estimation to take advantage of these hardware advances. This is achieved through a deeper understanding of the noise characteristics of OCT. Through mathematical ...

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    8. Identification of corneal mechanical properties using optical tomography and digital volume correlation (Thesis)

      Identification of corneal mechanical properties using optical tomography and digital volume correlation (Thesis)

      This work presents an effective methodology for measuring the depth-resolved 3D full-field deformation of semitransparent, light scattering soft tissues such as vertebrate eye cornea. This was obtained by performing digital volume correlation on optical coherence tomography volume reconstructions of silicone rubber phantoms and porcine cornea samples. Both the strip tensile tests and the posterior inflation tests have been studied. Prior to these tests, noise effect and strain induced speckle decorrelation were first studied using experimental and simulation methods. The interpolation bias in the strain results has also been analyzed. Two effective approaches have been introduced to reduce the interpolation bias ...

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    9. Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Optical coherence tomography (OCT) has become an essential tool in ophthalmology. The macular OCT images are three dimensional, high resolution and cross-sectional image of macula, which provides detailed structural information of various macular layers. Moreover macular OCT imaging is non-contact, noninvasive and real-time. OCT images can be obtained quickly and multiple times, this allows easy diagnosis and treatment progress monitoring. With advances in technology acquired dataset size is also increasing, which makes it impractical to manually segment macular layers in clinical environment. Thus need of fast and accurate segmentation algorithm is ever increasing. In this thesis two segmentation algorithms have ...

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    10. High contrast imaging of early demineralization on enamel surfaces using near-infrared polarized reflectance at lambda= 1460 and 1550 nm (Thesis)

      High contrast imaging of early demineralization on enamel surfaces using near-infrared polarized reflectance at lambda= 1460 and 1550 nm (Thesis)

      Introduction: In vivo and in vitro studies have shown that high contrast images of tooth demineralization can be acquired in the near-infrared at several wavelengths. The purpose of this study is to compare the lesion contrast in reflectance at near-infrared wavelengths coincident with high water absorption with those in the visible, the near-infrared at 1300nm, fluorescence, and polarization sensitive optical coherence tomography (PS-OCT) measurements for early lesions on buccal surfaces. Methods: Bovine incisors (n=40) were used in this in vitro study. Teeth were sectioned so that they were greater than 8mm in length, 2mm in width, and had at ...

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      Mentions: UCSF
    11. Handheld Micromanipulator for Robot-Assisted Microsurgery (Thesis)

      Handheld Micromanipulator for Robot-Assisted Microsurgery (Thesis)

      Robot-assisted surgery has been increasingly adopted in a wide variety of surgical applications because it offers fine manipulation with high precision and dexterity. Despite the commercial success of robotic platforms, practical use in microsurgery is still challenging due to a considerable level of accuracy required at sub-millimeter scales. Limited visualization and constrained accessibility also hinder operation under operating microscopes. Furthermore, lack of tactile feedback may lead to substantial and even irrecoverable injury. To address these issues in microsurgery, a handheld micromanipulator, Micron, has been introduced as an alternative to conventional robotic platforms. It allows surgeons to directly maneuver surgical tools ...

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    12. Doppler optical coherence tomography for microcirculation studies (Thesis)

      Doppler optical coherence tomography for microcirculation studies (Thesis)

      This thesis forms part of an ongoing long-term project to investigate the suitability of Doppler optical coherence tomography (OCT) as a measurement tool to investigate skin thickness and blood flow in patients with systemic sclerosis. There is a discussion of the characterisation of an electro-optic phase modulator for use in a Doppler OCT imaging system which is being built for the purpose of clinical studies. In addition to this the development of software for the same system is described. The work includes a comparison of two methods of obtaining Doppler information that were tested with the system; a phase resolved ...

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    13. Optical Coherence Tomography for Neurosurgery and Cancer Research (Thesis)

      Optical Coherence Tomography for Neurosurgery and Cancer Research (Thesis)

      Optical Coherence Tomography (OCT) provides non-labeling, real-time and high resolution images, which has the potential to transform the paradigm of surgical guidance and preclinical animal studies. The design and development of OCT devices for neurosurgery guidance and novel imaging algorithms for monitoring anti-cancer therapy have been pursued in this work. A forward-imaging needle-type OCT probe was developed which can fit into minimally invasive tools (I.D. ~ 1mm), detect the at-risk blood vessels, and identify tissue micro-landmarks. This promising guidance tool improves the safety and the accuracy of needle-based procedures, which are currently performed without imaging feedback. Despite the great imaging ...

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    14. Forward viewing OCT endomicroscopy (Thesis)

      Forward viewing OCT endomicroscopy (Thesis)

      A forward viewing fiber optic-based imaging probe device was designed and constructed for use with ultrahigh speed optical coherence tomography in the human gastrointestinal tract. The light source was a MEMS-VCSEL at 1300 nm wavelength running at 300 kHz sweep rate, giving an effective A-line rate of 600 kHz. Data was acquired with a 1.8 GS/s A/D card optically clocked by a maximum fringe frequency of 1 GHz. The optical beam from the probe was scanned by a freely deflecting optical fiber that was mounted proximally on a piezoelectric tubular actuator, which was electrically driven in two ...

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    15. The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      Percutaneous coronary intervention (PCI) is the most common treatment for coronary artery disease (CAD). The first form of PCI introduced was balloon angioplasty. After that, the advent of coronary stents (tubular wire mesh for intravascular mechanical support) led to a new era in interventional cardiology. Through the implantation of bare metal stents (BMS), all three limitations of balloon angioplasty – coronary artery dissection, elastic recoil and negative remodelling – are prevented. Unfortunately, bare metal stents have their own drawbacks: most significantly, in-stent stenosis as a result of deep focal vascular injury caused by stent struts, followed by excessive tissue proliferation. This drawback ...

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    16. Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      The cause of coronary artery neointimal thickness (NT) leading to restenosis in ~10% of drug-eluting stents (DES) is unknown, but adverse wall shear stress (WSS) may contribute. Prior studies comparing WSS to restenosis for first generation DES yielded conflicting results, and cited different mechanisms of action for DES agents. Studies to date have not accounted for stent geometry, which dictates local WSS patterns influencing drug concentration. The objective of this investigation was to evaluate current generation stent platforms via their WSS patterns and their respective impact on NT. We prospectively enrolled 19 patients, who were randomized to thin-strut (81μm ...

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    17. Optical and Photoacoustic Imaging for Ovarian Cancer Detection (Thesis)

      Optical and Photoacoustic Imaging for Ovarian Cancer Detection (Thesis)

      Ovarian cancer is the fifth most common cancer among women and has the highest mortality rate of all gynecologic cancers. Current clinical imaging modalities are limited by poor sensitivity and specificity. Therefore, there is an urgent need to develop effective tools to detect ovarian cancer. In this dissertation, two imaging modalities, optical coherence tomography (OCT) and photoacoustic imaging have been investigated for ovarian cancer detection and characterization. In the first modality, optical scattering coefficient, phase retardation and phase retardation rate were quantitatively extracted from polarization-sensitive OCT (PS-OCT) images. A highly positive correlation was found between those three parameters and collagen ...

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    18. Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Transgenic mouse models have been instrumental in the elucidation of the molecular mechanism behind many cardiac diseases such as Marfan syndrome. However, the small size of the murine heart has hampered the characterization of its cardiac morphology. In this project, we describe the development of a murine cardiac imaging modality using optical coherence tomography (OCT). After fixation and optical clearing, the hearts were imaged from multiple perspectives. These data sets were then corrected for refraction and registered together to yield a single volume of the whole heart. From this OCT volume, we then applied techniques from computational anatomy to quantify ...

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    19. Share your OCT Thesis on OCT News

      Share your OCT Thesis on OCT News

      OCT News is seeking links to bachelors, masters, and PhD theses in the area of "Optical Coherence Tomography". Traditionally student theses contain a great wealth of information but are rarely accessible to the OCT community. If you or someone you know wrote an OCT thesis and would like to share it with the community please submit a link or PDF using the "Contact OCT News" tab in the main menu bar or the feedback link in the footer and we will include it here: Student Theses. Thesis will only be included if the link is free of charge to users.

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    20. Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Roll-to-roll manufacturing of micro components based on advanced printing, structuring and lamination of ceramic tapes is rapidly progressing. This large-scale and cost-effective manufacturing process of ceramic micro devices is however prone to hide defects within the visually opaque tape stacks. To achieve a sustainable manufacturing with zero defects in the future, there is an urgent need for reliable inspection systems. The systems to be developed have to perform high-resolution in-process quality control at high speed. Optical coherence tomography (OCT) is a promising technology for detailed in-depth inspection and metrology. Combined with infrared screening of larger areas it can solve the ...

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    21. Adaptive optics optical coherence tomography for in vivo retinal imaging (Thesis)

      Adaptive optics optical coherence tomography for in vivo retinal imaging (Thesis)

      Optical coherence tomography (OCT) is a non-invasive micrometer-resolution volumetric imaging modality that has been employed in diverse applications. In this thesis, we first describe a GPU accelerated program to perform FDOCT data processing and real time 3D volumetric rendering. The real time visualization of volumetric images provided by the GPU acceleration was essential to the rest of the work described in this thesis. Small animal models of retinal diseases serve as a vital component in vision research, and non-invasive in vivo imaging is becoming an increasingly important tool in the field. We describe the first adaptive optics optical coherence tomography ...

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    22. Clinical applications of functional optical coherence tomography (Thesis)

      Clinical applications of functional optical coherence tomography (Thesis)

      The purpose of the work presented in this thesis is to show the potential of functional optical coherence tomography (OCT) to discriminate pathological from normal tissues in several clinical settings, by means of the attenuation coefficient. To that end, several fundamental studies were carried out to increase the fundamental understanding of the measured signals (in phantoms, during apoptosis) and both ex and in vivo investigations are performed in the urological and gynecological clinic.

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    23. In vivo evaluation of neointimal healing after stenting with optical coherence tomography (Thesis)

      In vivo evaluation of neointimal healing after stenting with optical coherence tomography (Thesis)

      Ischemic heart disease is still today the first cause of mortality in the world, especially in the developed countries. The vast majority of cases are due to atherosclerosis, a complex systemic degenerative process resulting in cholesterol accumulation in the extra-cellular space of the arterial intima, with inflammation, foam-cells formation, and necrosis. The clinical manifestations of coronary atherosclerosis comprise from stable angina, due to flow-limiting stenosis of the artery, to acute myocardial infarction or sudden death, when the atheroma gets complicated by thrombotic phenomena. The first revolution in the treatment of this disease came in 1977, when Andreas Grüntzig performed ...

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    24. Angiography and Monitoring of Hemodynamic Signals in the Brain via Optical Coherence Tomography (Thesis)

      Angiography and Monitoring of Hemodynamic Signals in the Brain via Optical Coherence Tomography (Thesis)

      The brain is a complex network of interconnected neurons with each cell functioning as a nonlinear processing unit. Neural responses to stimulus can be described by activity in neurons. While blood flow changes have been associated with neural activity and are critical to brain function, this neurovascular coupling is not well understood. This work presents a technique for neurovascular interrogation, combining optogenetics and optical coherence tomography. Optogenetics is a recently developed neuromodulation technique to control activity in the brain using light with precise spatial neuronal control and high temporal resolution. Using this method, cells act as light-gated ion channels and ...

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    1-24 of 129 1 2 3 4 5 6 »
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