心脏交感神经显像剂11C-N-CH3-Dopamine的合成及生物分布

Synthesis and biodistribution of 11C-N-CH3-Dopamine as a new cardiac sympathetic nerve imaging agent

目的 制备11C-甲基多巴胺（11C-MDA）,并探讨其作为心脏交感神经分子显像剂的可行性.方法 通过N端甲基化的方法合成11C-MDA,并用半制备HPLC进行分离纯化.取昆明小鼠30只,采用随机数字表法分5组,每组6只,静脉注射11C-MDA 7.4 MBq,分别于注射后2、5、10、20和30 min断颈处死,收集血液、心、肺、肝、脾、肾、胃、肠、脑、肌肉、骨等组织器官,测质量及放射性计数,经衰减校正后计算放射性摄取（％ID/g）.取中华小型猪6只,同样随机分为正常组和抑制组,每组3只,行11C-MDA PET/CT显像.抑制组先按体质量静脉注射10 mg/kg盐酸丙咪嗪,30 min后静脉注射11C-MDA 370 MBq.采用SPSS 15.0软件进行统计分析.结果 11C-MDA的总制备时间为45 min,标记率为（20±3）％,为无色澄明液体,pH值为6.5,放化纯＞98％,比活度为50 GBq/mmol.静脉注射11C-MDA后2 min,小鼠心脏放射性分布达到高峰,心肌摄取率为（8.78±1.18） ％ID/g,并随时间逐渐下降;11C-MDA主要经肝、肾代谢.中华小型猪PET/CT显像示,正常组心肌放射性摄取明显,图像清晰;而抑制组放射性摄取减低或缺失,图像模糊.结论 11C-MDA合成简便易行,制备成本低,心肌摄取率高,是一种具有潜在临床应用价值的心脏交感神经显像齐.

Objective To synthesize 11 C-methyldopamine （MDA） and to explore its feasibility as an agent for cardiac sympathetic nerve imaging.Methods 11 C-MDA was synthesized by direct N-methylation method and purified by semi-preparation reverse HPLC.Thirty Kunming mice were divided into five groups by random number table.The mice were respectively sacrificed at 2,5,10,20 and 30 min after injection of 7.4 MBq 11C-MDA.The lung,liver,spleen,kidney,stomach,intestine,brain,muscle,bone tissues and blood of mice were removed and weighed before radioactive γ-counting.The %ID/g was calculated.Six Chinese mini-swine were divided into normal group （n=3） and inhibition group （n =3） for myocardial imaging.Mini-swine of inhibition group were injected with 10 mg/kg imipramine hydrochloride at 30 min before 11C-MDA （370 MBq） injection.The data were analyzed with SPSS 15.0 software.Results The synthesis of 11 C-MDA took 45 min with radiochemical yields of （20±3）%.The solution of11 C-MDA was colorless and the pH value was 6.5.The radiochemical purity was more than 98% and the specific activity was 50 GBq/mmol.The myocardial uptake reached the peak value of （8.78± 1.18） %ID/g at 2 min after injection of 11 C-MDA in mice.11C-MDA was mainly metabolized through liver and kidney.PET/CT imaging showed that 11 C-MDA was highly uptaken in swine myocardium and could be blocked by imipramine hydrochloride.Conclusions 11C-MDA can be synthesized by a simple and economic method.The high uptake rate of 11 C-MDA in the heart suggests it may be a potential agent for cardiac nerve imaging.