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

JIA Bingzhen; LI Ruijun; NAN Lihong; LI Tongli; DU Jiaojiao; DING Wenyu; LI Dong; ZHANG Zhang

doi:10.19300/j.2024.L21021

Abstract：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/V3/4)were calculated.The CT flow reserve fraction(FFRCT)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(FFRCT>0.8 and FFRCT≤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 FFRCT(FFRCT>0.8 and FFRCT≤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).MBFLAD,KLAD,KLCX,and KRCA 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%),KLCX had the highest accuracy(77.3%),KRCA had the highest sensitivity(100%)and negative predictive value(100%),the MBF patient had the highest AUC(0.795),and MBFLCX 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.