Theory, Instrumentation, and Applications of Electron Paramagnetic Resonance Oximetry

Electron paramagnetic resonance (EPR), also called electron spin resonance, is a magnetic resonance-based technique capable of measuring oxygen levels in biological sampling. EPR oximetry is a minimally invasive magnetic resonance method capable of measuring direct and absolute values of pO2 or O2 concentrations. Significant developments have been made in spin probe synthesis and encapsulation, instrumentation development, and algorithm development for data collection and processing. Despite all of the progress, translation of EPR oximetry to broad clinical applications has been hindered by lack of SNR at low frequencies, long acquisition times, and lack of FDA-approved spin probes suitable for implantation. EPR oximetry has been used to evaluate the relationship between elevated levels of tissue pO2 and healing of radiation-damaged tissues. EPR oximetry holds a lot of promise for large animal models and potential clinical applications involving humans.