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

Master of Science in Biomedical Engineering (MSBME), Wright State University, 2020, Biomedical Engineering

Optical imaging has demonstrated potential as a medical imaging modality for measuring tissue functionality. Recently, interest in fluorescence guided surgery has emerged from improvements in optical imaging that have allowed real-time feedback. Of the optical imaging modalities, spatial frequency domain imaging (SFDI) has gained a lot of interest. Unlike spectroscopic techniques, such as functional near infrared spectroscopy (fNIRS) and frequency domain spectroscopy that measure bulk tissue properties, SFDI quantifies tissue functionality locally and wide field making it practical for clinical applications. Unfortunately, traditional SFDI systems use multi-pixel detectors, which may not exhibit ideal spectral characteristics, have limited sensitivity, be expensive, or bulky in size. On the other hand, avalanche photodiodes (APD) and single photon counting modules (SPCM), are much more sensitive to the spectrum ideal for optical imaging, inexpensive, and compact in size. Traditionally, an array of photodiodes are required to capture an image, but with the advent of single pixel cameras entire images can be captured with a single photodiode. In this thesis, a novel single pixel camera (SPC) is used to capture an image of the light field projected by an SFDI system to explore its feasibility as a detection method relative to a traditional charged-coupled device (CCD) or scientific complementary metal-oxide semiconductor (sCMOS) camera. To determine the feasibility of single pixel SFDI, both sCMOS and SPC SFDI implementations were built to measure the optical properties of a brain tissue simulating phantom. In the results chapter, the mean optical scattering and absorption properties are reported for regions of high and low optical absorption indicating single pixel camera spatial frequency domain imaging (SPC SFDI) is viable given certain applications. In Chapter 1, I provide the motivation and significance of single pixel spatial frequency do (open full item for complete abstract)

Committee: Ulas Sunar Ph.D. (Advisor); Tarun Goswami D.Sc. (Committee Member); Josh Ash Ph.D. (Committee Member) Subjects: Biomedical Engineering

Master of Science in Biomedical Engineering (MSBME), Wright State University, 2016, Biomedical Engineering

Burn injuries such as thermal burns, which are caused by contact with flames, hot liquids, hot surfaces, and other sources of high heat as well as chemical burns and electrical burns, affects at least 500,000 people in the United States, to which 45,000 of them require medical treatment and 3,500 of them result in death. It has also been reported that in the United States alone, fire results in a death approximately every three hours and an injury every 33 minutes. Early knowledge about burn severity can lead to improved outcome for patients. In this study, the changes in optical properties in human skin following thermal burn injuries were investigated. Human skin removed during body contouring procedures was burned for either 10 or 60 seconds using a metal block placed in boiling water. Multi-wavelength spatial frequency domain imaging (SFDI) measurements were performed on each sample and the optical properties (absorption and scattering parameters) were obtained at each wavelength. Multi-wavelength fitting was used to quantify scattering parameters, and these parameters were compared to histologic assessments of burn severity. Our results indicate substantial changes in optical parameters and changes, which correlate well with respect to burn severity. This study shows the characterization of thermal burn injury on human skin ex vivo by using the optical method of SFDI with high sensitivity and specificity. Due to more challenging conditions of layered skin structures with differing thickness in humans, ongoing work tackles combining high-resolution ultrasound imaging with SFDI for more accurate quantification of optical properties during in vivo clinical studies.

Committee: Ulas Sunar Ph.D. (Committee Chair); Ping He Ph.D. (Committee Member); Jeffrey Travers M.D. Ph.D. (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Biophysics; Cellular Biology; Engineering; Medical Imaging; Optics; Physics