Leukoaraiosis: correlation of MR and CT findings with blood flow, atrophy, and cognition.

Hypodense periventricular white-matter lesions detected by CT (leukoaraiosis) and high-intensity T2 signals detected by MR imaging were correlated with measurements of local cerebral blood flow (LCBF), cerebral atrophy, and cognitive performance. Subjects studied included elderly volunteers who were neurologically normal (n = 6), patients with chronic cerebral infarctions and intact cognition (n = 2), patients with multiinfarct dementia (n = 14), and patients with Alzheimer dementia (n = 9). Leukoaraiosis correlated with periventricular high-intensity lesions detected by MR, LCBF reductions, cognitive impairments, and cerebral atrophy. Moderate to severe leukoaraiosis was associated with LCBF reductions in the cortex, basal ganglia, and frontal white matter. Periventricular MR lesions correlated with cerebral atrophy but not with cognitive impairments or reductions in LCBF. The exquisite sensitivity of MR revealed small lesions that did not correlate with LCBF reductions and cognitive impairments. Remote subcortical white-matter lesions detected by MR did not correlate with periventricular MR lesions, leukoaraiosis, LCBF, cerebral atrophy, or cognitive performance, indicating little clinical relevance. We concluded that diffuse cerebral hypoperfusion, particularly in combination with the poor collateral circulation of white matter surrounding the lateral ventricles, is responsible for leukoaraiosis.