9:30-9:45. Preliminary Evaluation of F-18 Fluorocholine (FCH) as a PET Tumor Imaging Agent

The purpose of this study was to develop and evaluate an F-18 labeled choline tumor imaging agent.FCH was synthesized through the intermediate F-18 fluorobromomethane that was used to alkylate dimethylethanolamine. The isolated FCH was evaluated in PC-3 human prostate cancer cells, PC-3 human prostate cancer xenograft studies, and human prostate and brain tumor patients.FCH was accumulated at a slightly lower rate than FDG in the cultures of PC-3 cells. Inhibition of choline transport and phosphorylation by hemicholinium-3 resulted in a 90% decrease in FCH uptake without altering FDG uptake. FCH had a similar biodistribution as C-14 choline in mice, with the liver and kidneys being the primary sites of uptake. Tumor uptake of FCH and FDG were comparable at 45-60 mins after injections. The tumor:blood ratio was higher for FCH (5.3 +/- 2.4) than for FDG (3.2 +/- 0.3). Brain uptake of FCH was 10% that of FDG. FCH-PET studies were compared to FDG-PET studies. In the prostate cancer patients, more lesions have been seen on the FCH studies than on the FDG studies, and the standardized uptake values (SUV) have been higher with the FCH. Decreases in FCH-PET SUV have been noted in patients treated by androgen deprivation. Patients with suspected recurrent brain tumors have had more clearly defined abnormal accumulation on the FCH-PET scans than on the FDG-PET scans. The FCH is not accumulated by normal cortex.FCH is a promising imaging agent for the evaluation of metastatic prostate cancer and recurrent brain tumor.