Present status of electron paramagnetic resonance (EPR) spectroscopy/imaging for free radical detection.

Our group and others have been working on the development of EPR imaging to obtain "in vivo" free radical images. Using a 280 MHz apparatus a pyrrolidine nitroxide free radical was localized in the rat abdomen and thorax during its kinetic in whole body. We investigated the role of different experimental and instrumental parameters on the resolution of the images. The conclusion of these studies is that the instrumentation presents the advantage to perform EPR measurements on whole body rats with limited sensitivity (50 microM). The present resolution (8 mm) allows to get images in which it is not possible to resolve all the organs; instead L-band instruments provide images of single organs (up to 25 mm in size) with a higher resolution.