Design and automated production of 11C-alpha-methyl-l-tryptophan (11C-AMT)

11C-alpha-methyl-l-tryptophan ([11C]AMT), a tryptophan metabolism PET tracer, has successfully been employed for brain serotonin pathway and indoleamine 2,3-dioxygenase (IDO) pathway related tumor imaging. We here report a reliable, automated procedure for routine synthesis of [11C]AMT based on an Eckert and Ziegler Modular-Lab system. The semi-preparative HPLC was incorporated into the system to improve chemical purity and specific activity. The 6-step radiosynthesis followed by HPLC-purification provided [11C]AMT in 5.3 ± 1.2% (n = 6, non-decay-corrected) overall radiochemical yield with radiochemical purity > 99% and specific activity of 35-116 GBq/μmol. Usually, 2.95 ± 0.65 GBq (n = 6, EOS) patient ready dose was produced from about 55.5 GBq [11C]CO2 in 50 min.