Deepti Shravankumar Vikram

My Story:

I am a Biophysics graduate student working on oxygen measurement and imaging using EPR with applications to cancer and heart disease. Along with EPR, I have done some MRI imaging as well for ex-vivo systems. My projects include evaluating the time-response of particulate probes and diffusion of oxygen in cells.

Thesis title:
Development of particulate-based EPR oximetry for regional, temporal, and rapid measurements in tissue

Abstract:
Electron paramagnetic resonance (EPR) oximetry is a useful research technique and a potential clinical tool. The goal of this dissertation was to establish particulate-based EPR oximetry for dynamic pO2 measurements in vivo and widen its applications for cellular and tissue systems. EPR oximetry was compared to a fluorescence technique in an experimental tumor model. The study found EPR oximetry to be a noninvasive, robust and reliable method for repeated measurements in tumors. In addition, the response time of particulate EPR probes was established to be faster than 3.3 ms. Consequently, EPR oximetry was used for measuring temporal oxygen changes in tissue. The study revealed the presence of inherent fluctuations of oxygen in normal and tumor tissue. The frequency of fluctuations was unaltered even if modifiers of oxygen change were used. Lastly, regional pO2 data in mouse and rat hearts were analyzed. A post-processing algorithm was used to determine components in EPR spectra obtained from probe implanted in the infarct heart. Overall, the above developments will help widen the scope of applications for particulate-based EPR oximetry and will further encourage evaluation of the technique as a potential clinical tool for tissue oxygen measurements.