Synthesis of pyruvate-1-11C as a radiopharmaceutical for tumor imaging.

Pyruvate-1-11C was prepared enzymatically by the exchange reaction of 11CO2 with the carboxyl group of pyruvic acid using pyruvate-ferredoxin oxidoreductase from Clostridium butyricum. 11C-Labeled pyruvate was purified by sublimation in specially made glassware. The radiochemical yield of pure pyruvate-1-11C was 80% 35 min after the end of bombardment. The distribution of 11C in tumor-bearing rabbits after an i.v. injection of pyruvate-1-11C was observed using a gamma camera. In contrast to normal organs, the tumor was positively visualized. We also conducted a number of successful clinical studies. A case of brain tumor which exhibited a positive image on positron-emission tomography (PET) using pyruvate-1-11C is presented.