Electron paramagnetic resonance (EPR) is a sensitive technique for the study of free radicals. EPR Imaging (EPRI), an adjunct to EPR spectroscopy, is rapidly emerging as an important tool for spatially resolved EPR studies. EPRI is a functional magnetic resonance imaging modality, because EPR spectral parameters can reflect useful physiological information. Projection reconstruction using the free induction decay (PR-FID) has demonstrated the capability of fast radio frequency electron paramagnetic resonance imaging of small objects. Several factors need to be considered in the development of resonators for time-domain EPR imaging methodology for in vivo applications. High-speed data acquisition and averaging system is very essential to fully exploit the faster electron spin relaxation times and achieve the optimal sensitivity and temporal resolution, needed for in vivo studies. Pulsed RF EPR imaging based on the PR-FID technique is a pure frequency encoding technique. Being a frequency encoding method, the PR-FID requires accurate phasing of the sampled magnetization. In this context, the spectrometer dead time plays a crucial role in pulsed RF EPRI. A novel pure phase encoding technique has been proposed to enhance the resolution of solid-state NMR imaging. This technique known as single-point imaging (SPI), also referenced as constant time imaging, has been later used for in vivo 11B NMR imaging. Abnormal values of pO2 are linked to many pathophysiological conditions (e. g., ischemic diseases, reperfusion injury, and oxygen toxicity). EPR imaging experiments were also used to study the differences in nitroxide reduction in normal muscle and implanted tumors. Overhauser MRI (OMRI) is a double resonance technique that couples the advantages of MRI with the sensitivity of EPR, by making use of the Over hauser effect. By saturating the EPR transition of a paramagnetic agent, the NMR signal intensities of the coupled water protons are enhanced by a significant factor by means of the Overhauser effect.