Value of the apparent diffusion coefficient for quantification of low-grade hepatic encephalopathy

BACKGROUND AND AIMS: Minimal hepatic encephalopathy (HE) is associated with poorer quality of life and increased work disability. Recently, low-grade cerebral edema has been implicated in chronic liver disease. METHODS: We measured the apparent diffusion coefficient (ADC) of water in various regions of the brains of patients with cirrhosis, and elucidated the significance of the evaluation of ADC in quantifying low-grade HE and predicting overt HE and survival. Forty patients with cirrhosis and 24 controls underwent diffusion-weighted imaging, and patients were followed up every month. RESULTS: The mean ADC values were increased in cirrhotic patients with minimal HE versus no HE or controls. Minimal HE patients separated from no HE patients with a sensitivity of 70 similar to 90% and a specificity of 85 similar to 90%. ADC values correlated with individual neuropsychological tests. ADC values of white matter, such as the frontal (log-rank test 4.35, P < 0.05) and parietal (log-rank test 5.98, P < 0.05) white matter, was predictive of further bouts of overt HE. CONCLUSIONS: ADC is a reliable tool for quantification of low-grade HE, and could predict the development of overt HE.