MEASURE OF MAGNETIZATION-TRANSFER IN MULTIPLE-SCLEROSIS DEMYELINATINGPLAQUES, WHITE-MATTER ISCHEMIC LESIONS, AND EDEMA

PURPOSE: To define the percentage of magnetization transfer of multipl e sclerosis (MS) plaques, ischemic white matter lesions, and vasogenic edema to determine whether this measurement can help differentiate th ese entities, METHODS: Findings were compared in 25 patients with prov ed MS, 20 patients with white matter ischemic lesions, and 72 patients with white matter edema (caused by tumors, infections, or acute/subac ute infarctions) in the periventricular system, centrum semiovale, and subcortical white matter. Magnetization transfer was performed using an on-resonance binomial pulse. The percentage of magnetization transf er of the normal white matter was also calculated. RESULTS: Magnetizat ion transfer was significantly higher in white matter ischemic lesions (range, 31% to 38%; mean, 34% +/- 0.6%) than in demyelinating plaques of MS (range, 19% to 28%; mean, 22.5% +/- 1%) and in edema (range, 29 % to 37%; mean, 30.2% +/- 0.4%). No statistical difference in percenta ge of magnetization transfer was found among lesions in the periventri cular system (34% +/- 0.6%), centrum semiovaie (35% +/- 0.5%), or subc ortical white matter (33% +/- 0.6%), or in vasogenic edema associated with tumors, infections, or infarction. CONCLUSION: Differences in mag netization transfer suggest less change of demyelination in white matt er ischemic lesions than in MS plaques and are significantly different in this respect from similar MS plaques. Magnetization transfer of ed ema was less than that of normal white matter or fell between ischemic abnormalities and MS plaques, Percentages of magnetization transfer b elow the mid-20% range is highly suggestive of demyelination. Vasogeni c edema, our surrogate for increased water content of white matter, ca used a decrease in the percentage of magnetization transfer.