Pharmacokinetic imaging of C-11 ethanol with PET in eight patients with hepatocellular carcinomas who were scheduled for treatment with percutaneous ethanol injection

PURPOSE: To evaluate the carbon 11 ethanol kinetics with positron emission tomography after intratumoral injection of the tracer and assess its redist ribution and dilution in patients who have hepatocellular carcinomas and wh o were scheduled for treatment with percutaneous ethanol injection. MATERIALS AND METHODS: The study included eight patients with hepatocellula r carcinomas. C-11 ethanol was administered via a puncture needle positione d with ultrasonographic guidance. Parametric images based on the Fourier tr ansformation were created for further analysis of the local distribution pa tterns of the tracer. The ratio of the 45-minute postinjection standardized uptake value to the 5-minute postinjection standardized uptake value was u sed for the evaluation of ethanol dilution. RESULTS: Five of eight tumors demonstrated almost constant uptake values af ter the initial distribution phase. In contrast, a rapid elimination of the C-11 ethanol from the tumor was documented in three of sight tumors. The 4 5 minute-to-5 minute ratio was 0.18-0.67 (median value, 0.56) in the tumors . The time-activity curves of the normal liver parenchyma increased slowly but steadily with time owing to a low ethanol elimination from the tumor. F ourier transformation demonstrated inhomogeneous parts on the amplitude ima ges in seven of eight tumors and random redistribution on the phase images in six of eight tumors. CONCLUSION: Inhomogeneous drug distribution and drug dilution in the target area are likely to be the major limiting parameters for therapy response.