[Evaluation of clinical usefulness of 11C-methionine positron emission tomography (11C-MET-PET) as a tool for liver functional imaging].

We studied 11C-MET-PET in 17 clinical cases, 10 patients with obstructive jaundice and 7 normal volunteers, and analyzed its efficacy for the evaluation of hepatic functional reserve in major hepatectomy candidates. Differential absorption ratio (DAR) of 11C was compared to the hepatic protein synthesis rate (HPS), which is measured as the incorporation rate of 3H-labeled leucine in protein fraction, using needle biopsied liver specimen obtained from each hepatic segment. In the cases of normal liver function, DAR was well correlated with HPS. Also in jaundice cases with two exceptions, low HPS segment was demonstrated as low DAR segment. Consequently, MET-PET images could clearly provide functional liver imaging. After injection to 11C-MET, the increase in rate of radioactivity of 11C in plasma protein fraction was higher in jaundice cases than in normal volunteers, which is in accord with the results of our former study that cholestatic liver has accelerated protein synthesis rate. In summary, since 11C-MET-PET could demonstrate liver functional imaging, it might be a possible tool for liver function assessment in major hepatectomy candidates.