Measurement of Oxygen by EPRI and EPRS

In this chapter, the authors attempt to provide an overview of what already has been accomplished in this field and also to indicate promising areas of research and possible future applications of these techniques. The chapter emphasizes the applications of electron paramagnetic resonance (EPR) oximetry to extended objects; more general reviews of EPR oximetry are available elsewhere. 1 - 4 For the purposes of this chapter, EPR imaging (EPRI) and EPR spectroscopy (EPRS) are defined as the use of EPR to obtain one- (1-D), two- (2-D), three- (3-D), or four- (4-D) dimensional images (including spectral-spatial images) and to obtain EPR spectra from macroscopic objects. Although there are several different types of imaging agents that can be used for these studies, nitroxides are used most frequently, and therefore, the discussion will assume the use of nitroxides unless otherwise specified. Recently, two new oxygen-sensitive paramagnetic probes have been developed which may significantly enhance ERPI and ERPS (Section VI).