心肌梗死过程MRI征象变化的动物实验研究

Animal Experimental Study on Changes of MRI Signs During Myocardial Infarction Process

目的 探讨心肌梗死演变过程中MRI征象变化规律。方法 同时低位结扎兔心左冠状动脉前降支及左旋支的方法制备心肌梗死动物模型 ,术前及结扎后 3 0min、1h、2h、4h、8h、1天、3天、1周、2周、4周分别行常规T1、PD、T2、增强、电影及标记MRI扫描 ,测量各区信号强度及室壁厚度。结果 缺血 3 0min缺血区即有心室壁变薄 ,以收缩期明显 ,心室壁增厚率降低 ,并逐渐加重 ;缺血 1h ,梗死区开始出现PD及T2高信号 ,逐渐升高 ,1周后开始降低 ,4周呈低信号 ,T1在4周时出现低信号 ;急性梗死期增强可见 ,注射Gd DTPA后 5min内正常心肌有强化 ,15～ 2 0min梗死边缘区环形强化 ,3 0min梗死中央区均匀强化。结论 MRI可以发现大面积早期心肌缺血 ,也可对各期心肌梗死进行鉴别。

Objective To evaluate the changes of MRI signs during the myocardial infarction.Methods Left anterior descending (LAD) and Left cricumflex (LCx) coronary artery were ligated simultaneously in rabbits.Before the operation,at 30 minutes,1 hour,2 hours,4 hours,8 hours,1 day,3 days,1 week,2 weeks,and 4 weeks after ligation,imagings on T1,PD,T2,enhancement,cine-MRI were obtained respectively,to measure the intensity and thickness in different regions of left ventricular wall.Results At 30 minutes after ligation,the ischemic local wall of left ventricle became thinner,more in contractile phase,and became worse gradually.At 1 hour after ligation,hyperintensity on PDWI and T2WI in region of infarction was found,and became higher gradually,then the signal descended in 1 week after ligation,hypointensity in 4 weeks; hypointensity on T1WI was found in 4 weeks in region of infarction; In acute myocardial infarction,normal myocardium was enhanced in 5 minutes after injection, ring enhancement could be found in the marginal region of infarction in 15-20 minutes,centre of infarction was enhanced in 30 minutes.Conclusion MRI can find the myocardial ischemia of large area at early stage and can comfirm the stages of myocardial infarction.