magnetic resonance imaging (MRI)
The visualisation of the distribution of nuclear spins (usually water) in a body by using a magnetic field gradient (NMR imaging). A similar technique, but less widely used, is to visualise the distribution of paramagnetic centres (EPR imaging).
PAC, 1997, 69, 1251. 'Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997)' on page 1284 (