MICROSCOPIC DISEASE IN NORMAL-APPEARING WHITE-MATTER ON CONVENTIONAL MR-IMAGES IN PATIENTS WITH MULTIPLE-SCLEROSIS - ASSESSMENT WITH MAGNETIZATION-TRANSFER MEASUREMENTS

PURPOSE: To assess for the presence of microscopic abnormalities in otherwise normal-appearing white matter on T2-weighted images in patients with multiple sclerosis (MS) by using magnetization-transfer (MT) measurements. MATERIALS AND METHODS: Twenty-three patients with MS and nine healthy control subjects underwent magnetic resonance (MR) imaging with a 1.5-T system. MT ratios (MTRs) were measured in 16 areas of normal-appearing white matter identified on conventional T2-weighted images in patients with MS. MTRs in the same white-matter locations in control subjects were determined. The two groups were compared. RESULTS: The mean whole-brain MTR of normal-appearing white matter in patients was. 40.13% +/- 1.37 (standard deviation; range, 36.31%-42.09%); in control subjects, 42.93% +/- 0.95 (range, 41.62%-44.50%). The difference was statistically significant (P less than or equal to .001). Except for the internal capsules, the difference in mean MTRs in each sublocation of the brain between patients and control subjects was statistically significant (P less than or equal to .05). CONCLUSION: MT measurements are more sensitive than conventional MR imaging in the detection of abnormalities beyond the resolution of T2-weighted imaging.