UBC Theses and Dissertations
Optimization of multimodal OCT for early cancer detection and diagnosis Abouei, Elham
In this thesis, I present improved optical imaging modalities for early cancer detection, diagnosis and prognosis of lung and cervical cancers in a minimally invasive fashion. Optical coherence tomography (OCT), which is based on low coherence interferometry of backscattered light, offers high resolution three-dimensional visualization of structures below the tissue surface. In contrast, autofluorescence imaging (AFI) detects spectral differences in fluorescence and absorption characteristics of endogenous fluorophores. A combined OCT–AFI system uses both complementary modalities to examine structural and molecular information, which may enable increased detection and characterization of features associated with disease. The motivation of this thesis is to improve the capabilities of OCT and OCT-AFI for the in vivo detection and localization of early cancers. Rotary-pullback catheter-based OCT or OCT-AFI systems suffer from motion-induced artifacts. In this thesis, I developed a method for the correction of these motion artifacts present in both 2D and 3D images collected with an endoscopic OCT-AFI system. I optimized and demonstrated the suitability of this method using real and simulated NURD (non-uniform rotation distortion) phantoms and in vivo endoscopic pulmonary OCT-AFI. Presented is a qualitative evaluation of this method showing an enhancement of the image quality and a proposed metric to quantitatively evaluate the correction method. Next, I evaluated a high resolution OCT system for early cervical cancer screening and diagnosis. My work characterized diagnostic OCT features of normal cervix as well as low-grade squamous intraepithelial lesions (LSIL), and high-grade squamous intraepithelial lesions (HSIL). We determined the sensitivity (100%), specificity (83%) and accuracy (85%) of this diagnostic technique in differentiating low-risk and high-risk cervical lesions. Lastly, I present a design for a forward-viewing fiber scanning high resolution OCT probe for in vivo cervical imaging in the clinic. To enable high resolution imaging but allow for sufficient depth penetration into tissue, OCT systems use near-infrared light ~1000 nm in wavelength. As well, I have investigated the suitability of a new supercontinuum light source for this application.
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