Magnetic resonance is the most sensitive para-clinical method available for the 
diagnosis of multiple sclerosis since it shows changes in 95% of the patients 
with clinically definite multiple sclerosis. However, little correlation has 
been found, in different studies, between the parameters of magnetic resonance 
and the degree of neurological disability. The development and gradual 
application of new techniques of magnetic resonance, which permit specific 
detection of the lesions with the greatest degree of nerve dysfunction, permits 
improvement in the use of this technique for study of the natural history of the 
disease and thus to monitor patients given new treatments.