[1-11C] DL-valine, a potential pancreas-imaging agent.

There is a great need for a better pancreas-imaging agent. Studies with [1-14C] DL-valine have shown this amino acid to have a high pancreatic specificity in the four animal species examined. The tissue distribution was almost optimal by 30 min after injection, and no carrier effect was observed through a dose of 5 mg/kg. [1-11C] DL-Valine was synthesized in amounts up to 363 mCi using a rapid (T1/2 = 20.4 min for C-11), high-temperature, high-pressure modification of the Bücherer-Strecker amino acid synthesis. Purification was by anion-exchange followed by cation-exchange chromatography. [1-11C] DL-Valine was obtained in a 70% chemical yield with a total synthesis and purification time of 45 min. Studies in animals have demonstrated that it is a potentially useful new agent for clinical pancreatic imaging.