^(99m)Tc-Q_3与^(201)Tl在不同流量冠脉灌注的离体兔心肌中的清除及存留特性研究

A Comparison Between ^(99m)Tc-Q_3 and ^(201) Tl on Clearance and Retention Properties at Varying Coronary Flow Rates in Isolated Rabbit Heart

目的 探讨不同流量冠脉灌注的离体兔心肌对 99m Tc- Q3和 2 0 1 Tl的清除及存留特性 ,进一步揭示 99m Tc- Q3和 2 0 1 Tl在不同流量冠脉灌注的离体兔心肌中的摄取、清除及存留量之间的关系。方法 选用 2 0只新西兰大白兔 ,于麻醉下开胸 ,摘取心脏 ,建立离体兔心脏灌流模型。采用双核素法进行离体兔心脏灌注。结果 心肌对 2 0 1 Tl的净摄取值大于 99m Tc- Q3,但其改变受血流灌注量影响也比 99m Tc- Q3更明显。高流量灌注组 ,注射示踪剂后4～ 2 5分钟内 ,2 0 1 Tl的清除比 99m Tc- Q3清除更快 ;低流量灌注组 ,注射示踪剂后 40分钟内 2 0 1 Tl清除比 99m Tc- Q3快。高流量灌流组中观察到的 2 0 1 Tl早期快速清除现象在低流量灌注组中未出现 ,而 99m Tc- Q3在两组中均未见早期快速清除。结论 由于 2 0 1 Tl的清除比 99m Tc- Q3清除更快 ,其较高摄取的优势在药物注射后 10分钟时已完全丧失 ,故 99m Tc- Q3仍不失为一种优良的心肌灌注显像剂 ,值得进一步研究。

Objective This study was intended to investigate and compare technetium 99m N,N′ ethylenebis(acetylacetoneiminato)bis〔tris (3 methoxy 1 propyl) phosphine〕 ( 99m Tc Q 3) versus 201 Tl on clearance and retention properties at varying coronary flow rates in isolated rabbit heart. Methods 20 New Zealand White rabbits were anaesthetized and excised through a median sternotomy. The hearts were isolated and arrested in ice cold saline. The external perfusion models with isolated rabbit hearts were installed and were perfused at flow rates ranging from 0.52 to 3.75 ml/(g wet wt·min) in the absence of tracer recirculation. Furthermore, 99m Tc Q 3 experimental relations between uptake, clearance and retention were explored in comparison with 201 Tl. Results 201 Tl net uptake was higher and also more affected by flow rates ( P < 0.05 ) as compared with 99m Tc Q 3 net uptake. 201 Tl clearance was faster than 99m Tc Q 3 clearance within 4 to 25 minutes after radiopharmaceuticals injection in high flow rates group, and 201 Tl clearance was faster than 99m Tc Q 3 clearance within 40 minutes after radiopharmaceuticals injection in low flow rates group. 201 Tl earlier rapid clearance observed in the high flow rates group did not appear in the low flow rates group, but 99m Tc Q 3 did not display early rapid clearance either in the high flow rates group or in the low flow rates group. Conclusion Owing to faster clearance, the superiority of 201 Tl over 99m Tc Q 3 as a myocardial perfusion imaging agent would be lost entirely within 10 minutes after injection of agent, therefore 99m Tc Q 3 is still a good myocardial perfusion imaging agent, and further study is worth doing.