Category: Student Theses

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.

Medical imaging is a discipline where the fields of mathematics, physics, biology, and medicine are combined in the acquisition, computation and interpretation of threedimensional images of (human) tissue. A variety of imaging modalities that provide information about morphological structure and function of biological tissues has been developed. These modalities are based on electromagnetic waves (magnetic resonance imaging, X-ray computed tomography, confocal microscopy), sound (ultrasonography), or nuclear tracers (positron emission tomography, single photon emission computed tomography). In the last decades, these medical imaging modalities have become a key tool in disease diagnosis, treatment monitoring, and disease prevention. Compared to other imaging ...

Retrograde trans-synaptic degeneration (RTSD) in the human visual pathway has not been well clarified. Aims 1. To confirm the RTSD in human visual pathway. 2. To study the rate of RTSD. 3. To study the pupil function in the RTSD. Methods: 1. The peripapillary retinal nerve fibre layer (RNFL) thickness measured with optical coherence tomography was compared among patients with acquired and congenital retrogeniculate lesions and normal subjects. Humphrey perimetry and brain imaging were performed. 2. A relationship between the duration of the disease and the RNFL thickness measured at a single time point was evaluated. Additionally the RNFL thickness ...

Optical coherence tomography (OCT), a diagnostic tool which can perform non-contact, noninvasive, cross-sectional imaging of the retina and anterior eye in real time, has dramatically improved in its resolution and speed in the recent years. In addition to the advancement in hardware, different OCT methods for functional measurements, such as Doppler OCT for quantifying blood flow and generating angiography using OCT phase information, polarization sensitive OCT for measuring intrinsic mechanical / optical tissue property using light of different polarizations, and spectroscopic OCT for measuring blood oxygenation using multiple wavelengths, have been demonstrated and developed. In this thesis, a dual-wavelength spectroscopic OCT ...

Optical coherence microscopy (OCM) is an imaging modality that is capable of visualizing structural features of biological samples at high resolution based on their scattering properties. Interferometric synthetic aperture microscopy (ISAM) is a newer technique that can overcome the typical dependence between lateral resolution and depth-of-focus of an optical coherence tomography (OCT) imaging system by offering spatially invariant resolution within the whole 3D data set, including regions that are outside of the focal region. Both OCM and ISAM have many potential research and clinical applications. By combining OCM and ISAM, it is possible to visualize an entire 3D volumetric data ...

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 ...

Optical coherence tomography (OCT) has been widely used in biomedical imaging ever since its introduction. However, the application of OCT for biometrics is relatively new. This thesis demonstrates the feasibility of applying a spectral domain optical coherence tomography (SD-OCT) system to fingertip biometric information retrieval. The results show that SD-OCT is capable of retrieving Level 3 fingertip information. Combined with traditional Level 1 and 2 fingerprint information, which can also be easily acquired by SD-OCT, the proposed application shows potential for ultra-secure scenarios. Photoacoustic microscopy (PAM) is another imaging modality gaining considerable interest in the past decade. Different than OCT ...

The last thirty years have experienced tremendous advancement in our understanding of light-tissue interactions in the human retina. Nevertheless, major gaps remain, and our modeling of light return from the back of the eye continues to evolve. The objective of this thesis is to investigate one of these gaps, specifically that related to the directional property (angular dependence) of the retinal reflection and in particular that of cone photoreceptors. Directionality of cones is commonly referred to as the optical Stiles-Crawford effect (SCE). While cone directionality is well known to originate from their waveguide properties, considerable uncertainty remains as to which ...

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 ...

The ability of optical imaging techniques such as optical coherence tomography (OCT) to non-destructively characterize engineered tissues has generated enormous interest recently. The engineered tissue of interest here is the collagen gel, wherein smooth muscle cells (SMCs) are embedded in a 3D collagen I matrix. This thesis focuses on characterizing collagen gels quantitatively, by measuring the optical properties – the scattering coefficient s and anisotropy factor g – from OCT data by fitting the signal to a theoretical model. μ[subscript s] and g are macroscopic physical properties that provide information on the density and size of scattering particles in the sample ...

Obtaining accurate needle placement is of critical importance in many medical scenarios. In the setting of fine needle aspiration biopsy (FNAB), manual palpation is often the only cue for determining the optimal position of the needle. As a result, FNAB procedures frequently yield non-diagnostic tissue. When not guided by an imaging modality, breast and thyroid FNAB's only obtain diagnostic tissue in approximately 65% of cases. Although the addition of noninvasive imaging technology has been shown to increase FNAB yield, it is time-consuming, relatively expensive, and often requires additional personnel with specialized expertise. A need exists for low-cost, small, simple ...

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 ...

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 ...

Optical coherence tomography (OCT) is a micrometer-resolution imaging technique that produces cross-sectional images of sample microstructure by measuring the amplitude and echo time delay of backscattered light. OCT imaging is performed using low-coherence interferometry, typically with a fiber optic Michelson interferometer. OCT imaging has recently been performed by measuring the spectrum of the interference signal in the Fourier domain. In "swept source OCT" implementations, the interference spectra are generated with a wavelength-swept laser and photodetector. Axial image lines are obtained via Fourier transformation of the spectra. Fourier domain techniques have extended OCT imaging speeds from several thousand to hundreds of ...

Interventional cardiology has witnessed tremendous change since 1977 when Andreas Gruentzig successfully performed the first balloon angioplasty. Whereas initial concerns revolved around maintaining vessel patency with issues of recoil and restenosis, the introduction of stents changed the landscape forever. Inherent with their use, stents, and, more specifically, drugeluting stents (DES), have become central to improved patient outcomes but, at some cost. Catastrophic, yet fortunately still rare complications such as stent thrombosis have re-ignited an intense need for greater scrutiny when developing and, subsequently implanting DES into our patients. The demand for detailed information regarding coronary artery disease has seen intravascular ...