MR imaging and 1H spectroscopy of brain metabolites in hepatic encephalopathy:: Time-course of renormalization after liver transplantation

PURPOSE: To evaluate changes in hydrogen 1 magnetic resonance (MR) spectroscopic findings in overt or subclinical hepatic encephalopathy (HE) after liver transplantation and to compare these changes with clinical outcomes and basal ganglia high signal intensity (BGH). MATERIALS AND METHODS: Twenty-two patients scheduled for liver transplantation and 17 healthy control subjects were examined with H-1 MR spectroscopy and standard nonenhanced MR imaging. Eight patients underwent complete MR imaging and H-1 spectroscopic examinations before liver transplantation and at 3-4-week, 12-28-week, and 10-12-month follow-up after liver transplantation. RESULTS: Before liver transplantation, typical 1H spectroscopic changes-decreased myo-inositol (ml)/creatine (Cr) and choline (Cho)/Cr ratios and an elevated glutamine and glutamate (Glx)/Cr ratio-were found in 21 patients. Eighteen patients had BGH at T1-weighted imaging. Three to 7 months after liver transplantation, the ml/Cr and Glx/Cr ratios were within the normal range in five of eight and eight of eight patients, respectively, without any residual signs of subclinical or overt HE; however, at MR imaging, seven patients still had BGH. CONCLUSION: After successful liver transplantation, renormalization of HE-specific brain metabolite changes is detected at H-1 spectroscopy and precedes the disappearance of BCH. The neuropsychologic signs of subclinical or overt HE follow the changes seen at H-1 spectroscopy rather than those seen at MR imaging.