MAGNETIZATION-TRANSFER - A POTENTIAL METHOD TO DETERMINE THE AGE OF MULTIPLE-SCLEROSIS LESIONS

PURPOSE: To determine whether magnetization transfer contrast can diff erentiate acute from chronic lesions in multiple sclerosis. METHODS: T hirteen patients with multiple sclerosis and eight healthy patients we re studied with MR using a 0.1-T system. Relatively T2-weighted spin-e cho images were obtained without and with magnetization transfer contr ast. The magnetization transfer effect of multiple sclerosis lesions w as calculated and compared with the ages of the lesions. The magnetiza tion transfer effect of normal-appearing white matter in patients with multiple sclerosis was calculated and compared with the magnetization transfer effect of white matter in healthy volunteers. Statistical an alysis was performed. RESULTS: White matter in the healthy volunteers had values from 0.40 to 0.45. Normal-appearing white matter in the pat ients with multiple sclerosis had magnetization transfer effect values ranging from 0.41 to 0.45. Multiple sclerosis plaques of less than 1 year's duration had magnetization transfer effect values ranging from 0.05 to 0.26; older plaques had values from 0.25 to 0.41. The differen ce in the distributions of these values for acute and chronic multiple sclerosis plaques is statistically significant. CONCLUSION: Current i maging modalities do not differentiate acute multiple sclerosis lesion s from chronic ones. Our data on magnetization transfer show a statist ically significant difference in magnetization transfer effect values between lesions of less than 1 year's duration and older lesions. The different values may correspond to the histologic changes of multiple sclerosis plaques over time. Magnetization transfer may be a reliable method for determining the age of multiple sclerosis lesions.