ABSTRACT
This chapter describes the electron paramagnetic resonance (EPR) imaging (EPRI) and EPR spectroscopy (EPRS) that are defined as the use of EPR to obtain one-, two-, three-, or four-dimensional images and to obtain EPR spectra from macroscopic objects. The ability to measure intracellular concentrations of oxygen by EPR may represent an important advance in the technology of biological oximetry. A second class of EPR oximetric methods relies on a more indirect approach: the oxygen dependence of the rates of metabolism of EPR sensitive probes. Melanin is the only other free radical that has been used extensively as a probe in EPR oximetric methods. Some of the earliest EPR oximetry experiments used the effect of oxygen on the superhyperfine structure of nitroxides. In many ways, spectral-spatial imaging combines the most desirable features of the various approaches to the measurement of oxygen by EPR.
