心肌超声造影结合计算机灰阶分析技术对兔心肌灌注的研究

Study of myocardial perfusion in rabbits by myocardial contrast echocardiography combined with computer gray analysis

目的探讨心肌超声造影(MCE)联合计算机灰阶分析技术定量评价心肌灌注的应用价值。方法30只兔根据阻断和再灌注冠状动脉左室支时间不同分为两组:阻断30 min再灌注60 min(Ⅰ组)和阻断120 min再灌注60 min(Ⅱ组)。于阻断时和再灌注后行MCE,造影图像经自制计算机辅助灰阶分析软件处理后,自动得出每个节段心肌的标化灰阶造影剂密度(CI),并对心肌灌注进行彩色编码。根据心肌灌注缺损(MPD)和异常的彩色编码区分别计算出危险心肌和梗死心肌面积,分别与荧光微球染色和氯化三苯基四氮唑染色(TTC)结果对照分析。结果再灌注后,Ⅱ组危险节段的标化CI值比非危险节段明显减低(P<0.01),而Ⅰ组危险节段的标化CI值与非危险节段间无明显差异。以标化灰阶CI为-70 pix为截断值,识别梗死节段的敏感性为95%,特异性87%。阻断时,MPD和异常彩色编码测量的危险心肌面积与荧光染色呈正相关(r=0.84,P=0.003和r=0.91,P<0.001);再灌注时,MPD和异常彩色编码测量的梗死心肌面积与TTC结果呈正相关(r=0.75,P<0.001和r=0.89,P<0.001)。结论心肌超声造影联合计算机灰阶分析技术可以定量评估心肌灌注,识别危险和梗死心肌区域。

Objective To evaluate the potential value of myocardial perfusion by myocardial contrast echocardiography （MCE） combined with computer gray analysis. Methods Thirty rabbits were divided into two experimental groups, which underwent 30 min （Group Ⅰ ） and 120 min （Group Ⅱ ） coronary occlusion followed by 60 min reperfusion. MCE was performed on all rabbits during occlusion and after reperfusion, and their images were analyzed by a new computer gray technique. Myocardial gray calibrated contrast intensity （CI） values of six segments in left ventricular short-axis were measured and color-coded maps were produced automatically by software. The risk areas and infarct sizes obtained by myocardial perfusional defect （MPD） and color-coded map were compared with those by fluorescent microsphere and triphenyl-tetrazolium chloride （TTC） staining. Results Compared with non-risk segments, myocardial gray calibrated CI values were significantly decreased in risk segments in Group Ⅱ（P〈0.01） and no different in Group Ⅰ after calibration. Calibrated CI in -70 pix was an optimal cutoff point to identify infarcted seg ments and to yield the sensitivity of 95 % and specificity 87 %. The correlation between the risk area by MPD and fluorescent staining was 0.84 （P= 0. 003） whereas color-coded map and staining was 0.91 （P〈0. 001）. The correlation between the infarct size by MPD and TTC was 0.75 （P〈0. 001）, and between color-coded image and TTC was 0.89 （P〈0. 001）. Conclusion Myocardial contrast echocardiography combined with computer gray technique can assess quantitatively myocardial perfusion and identify automatically risk area and infracted region.