基于幂法则校正动态CT灌注心肌血流量评价心肌缺血

Evaluation of myocardial ischemia using myocardial blood flow corrected by the allometric scaling law in dynamic CT perfusion imaging

目的利用幂法则原理对心肌动态CT灌注(CTP)所测得心肌血流量(MBF)进行个体化校正,并评价其诊断心肌缺血的价值。方法回顾性纳入行CTP+冠状动脉CT血管成像(CCTA)扫描的疑似或确诊的冠心病病人86例,其中男47例,女39例,平均年龄(62.17±8.99)岁。使用Frontier平台分析病人MBF并计算冠状动脉三大分支支配区域的MBF。使用3D Slicer软件,通过阈值分割来计算冠状动脉管腔容量(V)并计算校正参数(K,K=MBF/V^(3/4))。利用AI影像辅助诊断平台计算靶血管病变部位的CT血流储备分数(FFR_(CT))值,并以FFR_(CT)>0.8和FFR_(CT)≤0.8在病人水平上分为非心肌缺血组和心肌缺血组,在血管水平上将冠状动脉3大主要分支[左冠状动脉前降支(LAD)、左冠状动脉回旋支(LCX)和右冠状动脉(RCA)]分别分为非缺血性狭窄组(FFR_(CT)>0.8)和缺血性狭窄组(FFR_(CT)≤0.8)。使用独立样本t检验比较病人水平和血管水平上不同分组之间MBF和K的差异,并绘制受试者操作特征(ROC)曲线评估其诊断效能。结果心肌缺血组MBF_(病人)和K_(病人)均低于非心肌缺血组(均P<0.05);缺血性狭窄组MBF_(LAD)、K_(LAD)、K_(LCX)和K_(RCA)均低于非缺血性狭窄组(均P<0.05)。K和MBF的诊断截断值分别为1.38和116 m L/(100 m L·min^(-1))时,K_(病人)的AUC(0.831)和阳性预测值(62.3%)最高,K_(LCX)准确度最高(77.3%),K_(RCA)敏感度(100%)和阴性预测值(100%)最高MBF病人的AUC(0.795)最高,MBFLCX特异度(89.1%)最高。结论基于幂法则原理可以使用病人冠状动脉灌注床的血管容量对MBF进行校正,并显著减少个体差异,提高CTP对心肌缺血的诊断效能。

Objective To correct myocardial blood flow(MBF)measured by dynamic CT myocardial perfusion(CTP)based on the allometric scaling law and evaluate its diagnostic value for myocardial ischemia.Methods We retrospectively collected data from 86 patients with coronary heart disease or suspected coronary heart disease(47 males and 39 females,average age:62.17±8.99 years)who underwent CTP+coronary artery CTA(CCTA)scan.The Frontier software analyzed MBF and calculated MBF in the three branches of the coronary artery.The coronary artery lumen volume(V)was obtained using the threshold segmentation function of 3D Slicer software,and the correction parameters(K,K=MBF/V^(3/4))were calculated.The CT flow reserve fraction(FFR_(CT))of the target vascular lesion site was calculated using an AI image-assisted diagnosis platform.The patients were divided into non-myocardial ischemia and myocardial ischemia groups based on FFRCT(FFR_(CT)>0.8 and FFR_(CT)≤0.8).The three main branches of coronary artery[left anterior descending coronary artery(LAD),left circumflex coronary artery(LCX),and right coronary artery(RCA)]were categorized into non-ischemic stenosis and ischemic stenosis groups based on FFR_(CT)(FFR_(CT)>0.8 and FFR_(CT)≤0.8).Independent sample t test was used to compare the differences in MBF and K between the non-myocardial ischemia and myocardial ischemia groups,and the receiver operating characteristic(ROC)curves were drawn to evaluate diagnostic efficacy.Results MBFpatient and Kpatient in the myocardial ischemia group were lower than those in the non-myocardial ischemia group(all P<0.05).MBF_(LAD),K_(LAD),K_(LCX),and K_(RCA) in the ischemic stenosis group were lower than those in the non-ischemic stenosis group(all P<0.05).When the cutoff values of K and MBF were 1.38 and 116 mL/(100 mL·min^(-1)),Kpatient had the highest AUC(0.831)and positive predictive value(62.3%),K_(LCX) had the highest accuracy(77.3%),K_(RCA) had the highest sensitivity(100%)and negative predictive value(100%),the MBF patient had the highest AUC(0.795),and MBF_(LCX) had the highest specificity.Conclusion Applying the principle of the allometric scaling law to correct MBF based on patients’coronary perfusion bed blood volume significantly reduces individual differences,enhancing the diagnostic efficiency of CTP for myocardial ischemia.