Simplified fast and high yielding automated synthesis of [18F]fluoroethylcholine for prostate cancer imaging

11C- and 18F-labeled choline analogues are successful tracers for prostate cancer imaging using positron emission tomography (PET). Due to the practical advantages of the longer-living radioisotope 18F (t1/2 = 110 min) instead of 11C (t1/2 = 20 min), [18F]fluoroethylcholine has been introduced to increase the opportunity of widespread clinical application. Nevertheless, the various known synthetic methods provide [18F]fluoroethylcholine for human use only in moderate overall yields of up to 30% so far.Here, a new simplified and high yield two-step-synthesis for [18F]fluoroethylcholine is described for potential clinical applications starting from 2-bromoethyl triflate (BETfO) using a modified, commercially available fully automated synthesis module. All synthesis parameters were subsequently optimized resulting in a total yield of 47 ± 5% (not decay corrected) in only 40 min. [18F]fluoroethylcholine could be obtained ready for human use as physiological solution after fixation on Sep-Pak Accell Light cartridges (waters®) and formulation with saline without the need of GC or HPLC purification. Radiochemical purity was >99.9% and no contamination of the sterile solution with chemicals used during the synthesis was detected.

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