Master of Science, Miami University, 2018, Physics

This thesis presents data from a series of experiments that investigate the ability of laser speckle contrast imaging (LSCI) to sense changes in flow in turbid media. I first provide a theoretical overview and a description of the experimental approach used in this flow imaging technique. Experimental validation of the technique's ability to sense induced changes in blood flow in the human forearm is demonstrated. Then, the technique's sensitivity to buried flow in controlled optical phantoms is examined. It is shown that the buried depth and optical properties of the media surrounding flow impact the measured flow indices. Lastly, a study shows how the polarization state of the imaged light impacts the flow measurements as a function of the buried depth and rate of the flow. The results demonstrate that the measurements are dependent on the flow rates and optical properties of the sample as well as the imaging setup used to capture the speckle.

Committee: Karthik Vishwanath (Advisor); Paul Urayama (Committee Member); E. Carlo Samson (Committee Member) Subjects: Biomedical Research; Biophysics; Medical Imaging; Optics; Physics

Doctor of Philosophy (PhD), Wright State University, 2023, Engineering PhD

Blood flow dynamics plays a critical role in maintaining tissue health, as it delivers nutrients and oxygen while removing waste products. It is especially important when there is a disruption in cerebral autoregulation due to trauma, which can induce ischemia or hyperemia and can lead to secondary brain injury. Thus, there is a need for noninvasive techniques that can allow continuous monitoring of blood flow during intervention. Optical techniques have become increasingly practical for measuring blood flow due to their non-invasive, continuous, and relatively lower-cost nature. This research focused on developing a low-cost, scalable optical technique for measuring blood flow by implementing speckle contrast optical spectroscopy using a fiber-camera-based approach. This technique is particularly well-suited for measuring blood flow in deep tissues, such as the brain, which is challenging to access using traditional optical methods. A two-channel continuous wave speckle contrast optical spectroscopy device was developed, and the device was rigorously tested using phantoms. Then, it is applied to monitor blood flow changes in the brain following traumatic brain injury (TBI) in mice. The results indicate that trauma-induced significant blood flow decreases consistent with the recent literature. Overall, this approach provides noninvasive continuous measurements of blood flow in preclinical models such as traumatic brain injury.

Committee: Ulas Sunar Ph.D. (Advisor); Tarun Goswami Ph.D. (Committee Member); Keiichiro Susuki Ph.D. (Committee Member); Robert Lober M.D., Ph.D. (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Biophysics; Engineering; Optics

Doctor of Philosophy (PhD), Wright State University, 2021, Engineering PhD

The research presented in this dissertation focused on the application of optical imaging techniques to establish blood flow and oxygen saturation as effective biomarkers for two disease cases, Autism Spectrum Disorder (ASD) and Huntington's Disease (HD). The BTBR mouse model of ASD was utilized to validate measurements of cerebral blood flow and oxygenation as biomarkers for autism. The R6/2 mouse model of juvenile HD was utilized to validate measurements of skeletal muscle blood flow following tetanic muscle contractions induced by electrical nerve stimulation. Next, a noncontact, camera-based system to measure blood flow and oxygen saturation maps was implemented to improve upon the previous HD mouse results by providing spatial heterogeneity in a wild-type mouse model. Finally, translational research was performed to validate a research design conducting concurrent grip strength force and skeletal muscle blood flow and oxygenation measurements in a healthy human population that will be used to establish HD biomarkers in humans in future clinical applications.

Committee: Ulas Sunar Ph.D. (Advisor); Andrew Voss Ph.D. (Committee Member); Sandra Kostyk M.D., Ph.D. (Committee Member); Tarun Goswami Ph.D. (Committee Member); Mark Rich Ph.D. (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Medical Imaging; Optics