[PET studies with C-11 ethanol in intratumoral therapy of hepatocellular carcinomas]

Positron emission tomography (PET) is a noninvasive functional method for the study of solid tumor perfusion, metabolism and interaction with different therapeutic agents. The aim of the study was the investigation of the metabolism of hepatocellular carcinomas (HCC) and the kinetics during a treatment with intratumoral ethanol by PET. The ongoing study includes seven patients with child. A cirrhosis and HCC (UICC stage III-IVA; tumor size 3-6 cm). Dynamic PET studies (60 min) with 18F-fluordeoxyglucose (FDG) were performed prior to therapy to assess tumor viability. The evaluation of the FDG data demonstrated a liver-equivalent uptake in six of the tumors (well and moderately differentiated HCC), which were poorly delineated against the normal liver parenchyma. One moderately differentiated HCC showed an increased FDG metabolism, indicating no correlation between histology and metabolism. A dose of 37-80 MBq 11C-ethanol was applied together with a nonlabelled therapeutic dose of the drug via a puncture needle positioned under sonography. Five out of seven tumors demonstrated a high 11C uptake shortly after the end of the ethanol injection followed by constant 11C-ethanol concentration during the whole study period of 45 min. The PET data demonstrated no significant elimination of the 11C-ethanol from the tumor and no accumulation in the surrounding liver tissue. One case showed a decrease of the intra-tumoral 11C-ethanol concentration due to a punkture of a tumor vein, and in another case the surrounding liver parenchyma demonstrated significant 11C uptake in the early phase following paratumoral injection of the drug. In conclusion, PET is a useful tool for the study of the mechanism and the kinetics of percutaneous intratumoral ethanol injection of HCC.