急性心肌梗塞后心肌血流的MCE与MRI实验研究

Assessment of Myocardial Blood Flow after Infarction with MCE and MRI (An Experimental Study)

目的 探讨心肌声学造影 (MCE)和MRI对急性心肌梗塞 (AMI)后残余心肌血流的诊断作用。方法 7只犬开胸结扎冠状动脉左前降支制作AMI动物模型 ,行活体MCE及离体灌注MRI检查 ,伊文思蓝和TTC染色分别确定缺血和梗塞区 ,放射微球99Tcm MAA测定心肌血流量 (MBF)。通过免疫组化和体视学方法测量和计算心肌微血管体积分数和微血管平均宽度。结果 正常心肌、缺血心肌和梗塞心肌声学造影强度分别为 5 3 .2 3± 6.14、2 3 .67± 6.14和 4.3 2± 4.11。MCE的A·β值与放射微球所测MBF高度一致和相关 ,缺血和梗塞区触发间隔 声强度曲线与灌注MRI时间 信号强度曲线表现一致。缺血和梗塞区心肌微血管的宽度和体积分数较正常心肌显著减少。

Purpose To study the value of myocardial contrast echocardiography (MCE) and magnetic resonance imaging (MRI) in the diagnosis of residual flow after infarction. Methods Seven dogs were given ligation of left anterior descending branch to make the pathologic models of acute myocardial infarction (AMI). MCE was performed in vivo dog hearts and perfusion MRI was performed in isolated hearts. Ischemic and infarcted regions were defined as Even's blue and 2,3,5 triphenyltetrazolium chloride (TTC) negative regions respectively. Myocardial blood flow was measured with radioactive microspheres( 99 Tc m MAA). The average width and the volume density of myocardial microvessels were determined and calculated with stereology and immunohistochemistry. Results The MCE intensity in normal regions was 53.23±6.14, in ischemic regions was 23.67±6.14, and in farcted regions was 4.32±4.11. A·β measured by MCE and the MBF measured by 99 Tc m MAA showed high correlation. The time intensity curves of MCE and perfusion MRI in ischemic and infarcted regions showed more consistency. The width and volume density of myocardial microvessels in ischemic and infarcted regions were reduced significantly than that in normal regions. Conclusion MCE and contrast perfusion MRI can determine the residual blood flow and the injury degree of myocardial microvessels after acute myocardial infarction.