Clinical applications of positron emission tomography in hepatic tumors.

Fluorodeoxyglucose (FDG), which allows the evaluation of glucose metabolism, is widely used for tumor diagnosis using positron emission tomography (PET). FDG-PET, which is used for the diagnosis of intrahepatic tumor lesions, shows high FDG accumulation in cholangiocellular carcinoma (CCC) and metastatic liver cancer. FDG-PET shows high FDG accumulation in moderately or poorly differentiated hepatocellular carcinoma (HCC) and is useful for the diagnosis of extrahepatic HCC metastases and recurrences. However, because the imaging method frequently shows low FDG accumulation in well-differentiated HCC, it is not very useful for that diagnosis. For the diagnosis of well-differentiated HCC, F-18 fluorocholine for evaluation of phospholipid metabolism and C-11 acetate for evaluation of free fatty acid metabolism are useful in the diagnosis of that HCC. It is expected that the combination of these PET agents will enhance the diagnostic performance of FDG-PET for HCC in the future. The problem of a lack of anatomical information is being resolved with the development of the use of PET in combination with computed tomography or magnetic resonance imaging. For the problem of low resolution, PET devices using semiconductors have been developed.