Improved Temporal and Spatial Resolution In Vivo Oxymetry Using Time-Domain EPR Imaging
Krishna C, Devasahayam N, Hyodo F, Mitchell J, Johnson C, Matsumoto K, Subramanian S
National Institutes of Health
Electron Paramagnetic Resonance (EPR) is a spectroscopic technique that detects and characterizes free radicals. EPR is capable of providing direct measurements of tissue oxygen concentration in a manner that is not dependent on complex biological processes. We describe the use of single-point imaging (SPI) in radiofrequency, Fourier-transform EPR. We present the techniques for performing oxygen imaging using EPR with phantoms and in vivo. Results from mouse tumor models demonstrate that the SPI EPR imaging technique readily distinguishes between normal and tumor legs and can track the changes in tissue oxygen concentration in response to percentage of oxygen in breathing gas.