The synthesis of a new cardiac sympathetic nerve imaging agent N-[11C]CH3-dopamine and biodistribution study

In this study, we synthesized and characterized N-¹¹C]methyl-dopamine (¹¹C]MDA) for cardiac sympathetic nerve imaging. ¹¹C]MDA was synthesized by direct N-methylation of dopamine with ¹¹C]methyl iodide and purified by semi-preparation reverse high pressure liquid chromatography (HPLC). The total synthesis time was 45 min including HPLC purification. The radiochemical yields of ¹¹C]MDA was 20 ± 3 %, without decay correction. The radiochemical purity was >98 % and the specific activity was about 50 GBq/mmol. The biological properties of ¹¹C]MDA were evaluated by biodistribution study in normal mice. PET imaging was performed in healthy Chinese mini-swines. Biodistribution study showed that ¹¹C]MDA had high myocardium uptake. PET/CT imaging showed ¹¹C]MDA had clear and symmetrical myocardium uptake, which was blocked obviously by injecting imipramine hydrochloride. ¹¹C]MDA would be a promising candidate of radiotracer for cardiac sympathetic nervous system imaging.