Improvement of Radiosynthesis Yield of [11C]acetate

Purpose [11C] acetate has been proved useful in detecting the myocardial oxygen metabolism and various malignancies including prostate cancer, hepatocellular carcinoma, renal cell carcinoma and brain tumors. The purpose of study was to improve the radiosynthesis yield of [11C]acetate on a automated radiosynthesis module. Materials and Methods [11C]acetate was prepared by carboxylation of grignard reagent, methylmagnesium chloride, with [11C]$CO_2$ gas, followed by hydrolysis with 1 mM acetic acid and purification using solid phase extraction cartridges. The effect of the reaction temperature 0circC, 10circC, $-55^{\circ}C$ ) and cyclotron beam time (10 min, 15 min, 20 min, 25 min) on the radiosynthesis yield were investigated in the [11C]acetate labeling reaction. Results The maximum radiosynthesis yield was obtained at $-10^{\circ}C$ of reaction temperature. The radioactivities of [11C]acetate acquired at $-10^{\circ}C$ reaction temperature was 2.4 times higher than those of [11C]acetate acquired at $-55^{\circ}C$ . Radiosynthesis yield of [11C]acetate increased with increasing cyclotron beam time. Conclusion This study shows that radiosynthesis yield of [11C]acetate highly dependent on reaction temperature. The best radiosynthesis yield was obtained in reaction of grignard reagent with [11C]$CO_2$ at $-10^{\circ}C$ . This radiolabeling conditions will be ideal for routine clinical application.ope