Redox-reactions are playing a significant role in regulation of homeostasis of organism.
Disorder of the redox-status is related with the onset and/or propagation of oxidative
diseases such as lifestyle-related diseases, including cancers and cardiac diseases,
etc. In vivo imaging of redox-status is thereby important in the analysis of mechanisms
of oxidative diseases and developments of new medicines for the diseases. Aminoxyl
radicals are redox-sensitive reporter molecules, which lose their paramagnetic moiety
by reactions of free radicals or reducing compounds. Electron spin resonance (ESR)
technique has been used to measure the molecules in vivo. In vivo spatial resolution
in ESR imaging is in the range of a few millimeters and is not sufficient for the
detailed diagnosis of disease models. Overhauser enhanced MRI (OMRI) is an emerging
free radical imaging technique, which utilised electron-proton coupling to image the
distribution of free radicals. In vivo imaging of redox-status is applicable with
OMRI/aminoxyl radical technique. The detailed imaging analysis was demonstrated in
oxidative diseases, such as tumour-bearing, neurodegeneration or gastric ulcer models.
The OMRI/aminoxyl radical technique has a large potential as a diagnostic system for
biomedical applications in the future.