Magnetic resonance imaging (MRI) has been shown to be a good method of 
visualizing the lesions in MS. We have studied several applications of MRI to 
the evaluation of patients and experimental models. In diagnosis, MRI is the 
most sensitive test for the demonstration of dissemination of lesions in space. 
Pathological correlation studies show that MRI reliably measures the extent of 
chronic demyelination. Experimental studies show that MRI detects acute 
inflammatory lesions and measures their evolution. MRI also is a reliable 
measure of the extent of the MS process, serial MRI scans detect evidence of 
disease activity in MS not always disclosed by clinical evaluation. MRI will 
have an enormous future impact on the evaluation of patients in clinical studies 
and in understanding the evolution of pathological processes.