Date of Award

Spring 2021

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Biomedical Engineering

First Advisor

Yu, Bing

Second Advisor

Stucke, Astrid

Third Advisor

White, Sarah

Abstract

Liver diseases are a significant cause of global health burden accounting for roughly 2 million deaths annually, among which half are caused by liver cirrhosis and the remaining half is due to hepatitis and hepatocellular carcinoma (HCC). These numbers suggest that both chronic and acute liver diseases contribute considerably to morbidity and mortality at the global level, and these numbers are expected to increase. These formidable numbers call for public health improvement. Liver needs maintenance of enough oxygen supply in order to function properly. As a result, it is pivotal to monitor the oxygen saturation of the liver in patients, especially during and after liver transplantation. Hypoxia or insufficient oxygen supply can lead to organ dysfunction and loss. Thus, there is a limited time to make interventions and restore oxygen supply back to normal. Diffuse reflectance spectroscopy (DRS) techniques have been used for different applications, including cancer research in liver, cervix, kidney and colon, oxygen saturation monitoring, and tissue damage assessment. Studies using DRS have shown promising results in determining morphological and physiological tissue information by extracting tissue optical properties, such as scattering coefficient and absorption coefficient, to quantify hemoglobin concentration and tissue oxygen saturation. In Aim 1 of the current study, we use a home-made fiber optic probe based visible DRS (vis-DRS) to investigate the effects of hemodilution(anemia) and the fraction of inspired oxygen (FiO2) changes on liver tissue oxygenation and oxygen-hemoglobin dissociation curve. We hypothesize that vis-DRS can produce accurate and reproducible measurement of Hb and tissue oxygenation in highly pigmented liver tissue in vivo. In Aim 2, we study the use of vis-DRS for real-time monitoring of laser ablation of liver tumors in rats. The utilization of thermal ablative techniques, including laser ablation, is currently on the rise since, in 80% to 95% of patients, surgery and resection are not a viable solution. In this study, 808 nm laser at different power settings (1, 1.5, and 2 watts) has been utilized to treat liver tumors in rats, and tumor optical properties have been continuously recorded during ablation. The correlation between different laser powers and changes in liver optical properties has been investigated.

Available for download on Sunday, July 23, 2023

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