Synthesis and evaluation of 1-[11C]methyl-4-aryl-piperazinium salts as myocardial imaging agents.

Our previous study with radioiodinated 1-methyl-1-(2-hydroxyethyl)-4- phenylpiperazinium derivatives indicated that these compounds localize selectively in the rat myocardium. Based upon these results, 1-[11C]methyl-1-alkyl-4-phenylpiperazinium cations were synthesized and evaluated for their potential as myocardial imaging agents. Biodistribution studies were performed in rats and imaging studies in normal dogs. The results indicate high concentrations of 3-4% ID/g in the rat heart at 5 min, comparable to those obtained with the radioiodinated analogs. Sequential imaging of the canine heart showed a similar pattern of uptake. The level of activity reached at 20 min was maintained over the 1-h time period. These results suggest that the phenylpiperazinium agents may have potential application as myocardial imaging agents.