MULTIPLE-SCLEROSIS LESIONS - RELATIONSHIP BETWEEN MR ENHANCEMENT PATTERN AND MAGNETIZATION-TRANSFER EFFECT

PURPOSE: To investigate the relationship between the enhancement patte rn of a multiple sclerosis lesion and its magnetization transfer effec t. METHODS: Fifty-four lesions were chosen from 29 patients with multi ple sclerosis on the basis of enhancement pattern on contrast-enhanced T1-weighted MR images. They included 14 homogeneously enhancing lesio ns, 26 nonenhancing lesions, and 14 ring-enhancing lesions. Magnetizat ion transfer ratios of the homogeneously enhancing lesions, nonenhanci ng lesions, and central portion of the ring-enhancing lesions were mea sured. Means were calculated and compared. RESULTS: The magnetization transfer ratios for homogeneously enhancing lesions were higher (mean, 32.2%; SD, 3.4%) than those for nonenhancing lesions (mean, 29.4; SD, 4.3%) and for the central portion of ring-enhancing lesions (mean, 24 .5%; SD, 4.0%). Significant differences were found between the ring-en hancing lesions and the homogeneously enhancing lesions and between th e ring-enhancing lesions and the nonenhancing lesions. CONCLUSION: We found a relationship between decreased magnetization transfer ratios a nd those enhancement patterns in which myelin is known to be decreased histopathologically, Thus, use of the magnetization transfer techniqu e may increase the specificity of MR imaging in assessing the extent o f residual myelination in multiple sclerosis lesions.