Magnetic resonance imaging and spectroscopy in hepatic encephalopathy.

Hepatic encephalopathy (HE) is a potentially reversible neuropsychiatric syndrome secondary to cirrhosis and other severe liver diseases. Magnetic resonance imaging (MRI) and MR spectroscopy (MRS) have been explored to provide new insight into the pathophysiology, diagnosis and treatment of HE. MRI shows brain atrophy especially in the frontal region. Globus pallidus, putamen and portions of the internal capsule appear hyperintense on T1-weighted images; this is likely to be due to deposition of manganese as a result of portosystemic shunting and liver dysfunction. MRS permits the detection and quantification of certain brain metabolites in vivo. There is decrease in myoinositol and choline concentrations and increase in glutamine concentrations. There is no change in n-acetyl-aspartate. Depletion of myoinositol is the most sensitive and specific spectroscopic marker in HE. Its loss is most likely a compensatory mechanism for the accumulation of glutamine. In conclusion, MRI and MRS examine different aspects of hepatocerebral disease.