Subcortical hypoperfusion associated with asymptomatic white matter lesions on magnetic resonance imaging

Background and Purpose We examined whether hemodynamic and metabolic abnormalities in the cerebral white matter, basal ganglia, and thalamus are associated with asymptomatic white matter lesions (WML) depicted on MR images. Methods A positron emission tomographic study with (H2O)-O-15, (CO)-O-15, and O-15(2) was performed in eight normal control subjects without any WML (mean+/-1 SD age, 68.5+/-10.2 years) and in 15 asymptomatic subjects with WML (71.3+/-8.5 years) to measure regional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and oxygen metabolic rate. Results In the cerebral white matter in the asymptomatic subjects with WML, significantly lower CBF (20.3+/-3.9 mL/100 mL per minute; P<.05) and significantly higher OEF (0.43+/-0.08; P<.05) were found compared with those for control subjects (23.5+/-2.6 mL/100 mL per minute and 0.37+/-0.06, respectively). The severity of WML was not related to the magnitude of hypoperfusion. In the basal ganglia, significantly lower CBF (44.9+/-6.9 mL/100 mL per minute; P<.01) and significantly higher OEF (0.54+/-0.08; P<.01) were found in the WML group than in control subjects (70.1+/-12.0 mL/100 mL/min and 0.39+/-0.03, respectively). In the thalamus, there was no significant difference in CBF and OEF between the control and WML groups. Conclusions Hypoperfusion of the cerebral white matter and basal ganglia in asymptomatic WML subjects may be induced by the arteriosclerosis of long penetrating medullary arteries and lenticulostriate arteries but may not be directly related to the production of WML. The role of hypoperfusion in the production of WML and acceleration of its development remains to he elucidated.