Free radical research is gaining significant attention in the biomedical community. This interest stems from the fact that free radicals are associated with the pathogenesis of many important disease processes including cancer, arteriosclerosis, Alzheimer's disease and in a variety of inflammatory diseases mechanisms. Free radicals are molecules with one or more unpaired electrons in their outer orbital and are therefore paramagnetic. By virtue of the magnetic moment of the unpaired electron, similar to NMR which derives its signal from the unpaired nuclear spin, it is possible to obtain similar information from the electron spin system by free radical spectroscopy and imaging techniques. Proton electron double resonance imaging (PEDRI) is a magnetic resonance (MR) based imaging technique which provides information about free radical distribution in the imaging volume on an MR image. Since the technique requires that the subject (sample) under study be irradiated at the electron frequency before the conventional MR image acquisition, and since the electron resonance frequency is normally in the microwave frequency range even at low magnetic fields (~10 mT), sample overheating is a problem in all biological samples which are composed of mainly water.
Developing methods to make PEDRI more feasible for studying biological samples has been the focus of my work in the PhD program. The unavailability of commercial scanners capable of performing PEDRI studies at variable fields has made it necessary to develop the instrumentation for the same. Novel resonator designs that may help to minimize power deposition in the imaging volume have been developed. Two novel applications namely pH imaging using pH sensitive nitroxide probes and oxymetry using oxygen sensitive paramagnetic molecules have been investigated.