Highly efficient automated synthesis of [11C]choline for multi dose utilization

[11C]Choline has been under investigation as a PET ligand for imaging tumor tissue, especially prostate cancer. An improved, automated synthesis of the tracer now was established. [11C] Choline was produced by labeling 2-(dimethylamino)-ethanol (DMAE) with [11C]CH3I in a Tefzel® tube at room temperature without solvent. The product was purified using a cation exchange cartridge. Reaction conditions were optimized with respect to synthesis time and amount of DMAE, resulting in radiochemical yields higher than 80% using 60 μl of DMAE in 20 min, radiochemical purity was >99% and residual DMAE was below 10 ppm. After 11C-production of 1 h at 50 μA [11C]choline activities of 30.0±5.6 GBq (n=29) were obtained in sterile solution ready for intravenous administration.