Detection of pyramidal tract lesions in amyotrophic lateral sclerosis with magnetization-transfer measurements.

PURPOSE To determine the presence of small lesions in the pyramidal tract in patients with amyotrophic lateral sclerosis (ALS) by using magnetization-transfer (MT) measurements and MR imaging. METHODS MT ratios (MTRs) were measured in the posterior limb of the internal capsule in nine patients with ALS and in nine healthy volunteers. RESULTS The mean value of MTRs (%) in patients with ALS was 15.76 +/- 1.48, while that of the control subjects was 19.83 +/- 1.54. The difference was statistically significant. CONCLUSIONS MT measurements are useful for detecting abnormalities associated with degeneration of the pyramidal tract in patients with ALS.