Leukoencephalopathy in normal and pathologic aging: 2. MRI of brain lucencies.

A pilot study was performed to test the ability of MR to evaluate the brain lucencies shown by CT in Alzheimer disease patients and in normal control subjects. Eight patients with presumed Alzheimer disease and 47 normal controls, 12 over the age of 45 years and 35 under age 45, were studied. Each group included subjects with and without CT evidence of leukoencephalopathy. Inversion recovery, saturation recovery, and spin-echo scans were obtained using a 0.3-T permanent magnet prototype unit. Results indicated that MR was more sensitive than CT to parenchymal disease. Seven of the eight patients with Alzheimer disease showed patches of increased signal intensity on SE scans; only three had lucencies on their CT studies. None of the normal subjects under the age of 45 showed periventricular patches of increased SE signal intensity. T2-weighted SE imaging was performed in nine of the 12 normal subjects over 45 years old. Eight of the nine demonstrated periventricular patches of increased SE signal intensity. Faint CT lucencies were present in only one of these. The configuration of the patches of increased signal intensity was similar for both the normal and Alzheimer groups, but the extent of white-matter involvement was greater in the Alzheimer group.