Pharmacokinetic imaging of 11C 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 redistribution and dilution in patients who have hepatocellular carcinomas and who were scheduled for treatment with percutaneous ethanol injection. MATERIALS AND METHODS: The study included eight patients with hepatocellular carcinomas. C-11 ethanol was administered via a puncture needle positioned with ultrasonographic guidance. Parametric images based on the Fourier transformation were created for further analysis of the local distribution patterns of the tracer. The ratio of the 45-minute postinjection standardized uptake value to the 5-minute postinjection standardized uptake value was used for the evaluation of ethanol dilution. RESULTS: Five of eight tumors demonstrated almost constant uptake values after 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 45 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. Fourier transformation demonstrated inhomogeneous parts on the amplitude images 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.