Combined optical coherence tomography and hyperspectral imaging using a double-clad fiber coupler

This work demonstrates the combination of optical coherence tomography (OCT) and hyperspectral imaging (HSI) using a double-clad optical fiber coupler. The single-mode core of the fiber is used for OCT imaging, while the inner cladding of the double-clad fiber provides an efficient way to capture the reflectance spectrum of the sample. The combination of both methods enables three-dimensional acquisition of the sample morphology with OCT, enhanced with complementary molecular information contained in the hyperspectral image. The HSI data can be used to highlight the presence of specific molecules with characteristic absorption peaks or to produce true color images overlaid on the OCT volume for improved tissue identification by the clinician. Such a system could be implemented in a number of clinical endoscopic applications and could improve the current practice in tissue characterization, diagnosis, and surgical guidance

The Clinical Application of Optical Coherence Tomography for Head and Neck Premalignant/Malignant Lesions

Abstract The principle of Optical Coherence Tomography (OCT) is based on the property of light coherence. OCT generates cross-sectional images of two-dimensional objects to obtain in-vitro and in-vivo images of tissues. Non–commercially available OCT systems, which have a higher resolution and scanning rate, have been previously reported. However, some clinical research has already been conducted using the first commercially available OCT device (Niris system) to image the larynx; but applications on oral and skin tissue have not been tested yet. This thesis aims to explore, compare and validate three specific types of commercially available OCT equipment for imaging head and neck tissue. An animal cancer model has been used to verify the feasibility of one system (Niris) to differentiate normal from malignant oral tissue, using in-vivo tissue samples. Since images of oral tissue samples didn’t show much structure using the Niris system, a different machine (Michelson Diagnostic bench based) with different specifications and resolution was employed. Great emphasis has been put on validating OCT structurally and histomorphometrically in comparison to the gold standard of pathology. This was tested and validated with ex-vivo oral and skin tissues using the lab based version of the machine. Use of an upgraded system (Michelson vivo sight with probe) has been tested on abnormal oral and skin biopsy tissue but with different timing for the scan (instant ex- vivo). One original study evaluated and classified tongue papilla atrophy from patients having their suspicious tongue lesions biopsied. In conclusion, this thesis concludes that the new version of this commercially approved OCT system can be applied to the diagnosis of superficial premalignant and malignant oral and skin lesions in-vitro. Furthermore, OCT holds the promise of complementing surgery to eradicate tumors and monitor the consequences

Changes in tear film metrics and ocular signs induced by different types of refractive correction in an aging population

No abstract available

Development and application of optical imaging techniques in diagnosing cardiovascular disease

textAtherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions.Biomedical Engineerin