CORRELATION OF MAGNETIZATION-TRANSFER RATIO WITH CLINICAL DISABILITY IN MULTIPLE-SCLEROSIS

We performed spin echo magnetic resonance imaging with and without app lication of an off-resonance saturation pulse in 43 patients with mult iple sclerosis (MS), 10 age-matched controls, and 4 elderly asymptomat ic patients with the radiological diagnosis of small-vessel disease. M agnetization transfer (MT) ratio images were obtained from these. All MS subgroups (primary progressive, secondary progressive, benign, earl y relapsing-remitting) showed significantly lower average lesion MT ra tios than small-vessel disease patients. Secondary progressive MS pati ents showed significantly lower lesion MT ratios than those with benig n disease, and there was an inverse correlation of disability with ave rage lesion MT ratio. The degree of reduction of MT ratios is an indic ator of the extent of tissue destruction. Thus, reduced MT ratios in M S may provide an indication of the degree of demyelination and axonal loss, both of which are likely to cause functional deficits in MS. We conclude that MT measurement is (1) a robust quantitative method that may increase the pathological specificity of magnetic resonance imagin g, (2) has the potential to differentiate demyelination in MS from les s destructive pathological changes, and (3) may be useful in monitorin g modifications in tissue structure brought about by treatment.