Reduction of increased signal intensity in the basal ganglia on T1-weighted MR images during treatment of hepatic encephalopathy.

A 61-year-old man with liver cirrhosis showed a symmetrical increase in the signal intensity of the basal ganglia on T1-weighted magnetic resonance (MR) images, which was diminished after 3 months of treatment for hepatic encephalopathy. He recovered from encephalopathy with treatment, and liver dysfunction (hyperammonemia and abnormal blood coagulation) as well as the results of quantitative psychometric tests showed a marked improvement. The cause of these high signal intensity changes on T1-weighted images and the reason for their partial reversibility are not known, but hyperammonemia due to portal-systemic shunting might be closely related to these clinical observations.