测量位点对CT瞬时无波比值诊断冠状动脉缺血特异性狭窄性能的影响

Effect of measurement sites on coronary computed tomography angiography-derived instantaneous wave-free ratio in the diagnosis of coronary stenosis ischemia

目的探究测量位点对CT瞬时无波比值(iFRCT)诊断冠状动脉缺血特异性狭窄准确度的影响。方法回顾性收集2009年2月至2018年5月在东部战区总医院放射诊断科行冠状动脉CT血管成像(CCTA)检查并接受有创性血流储备分数(FFR)检查的44例患者的资料,其中男27例,女17例,年龄40~83(59.3±9.3)岁。基于CCTA图像通过流体力学模拟计算不同位点(狭窄处、狭窄处下游近端、狭窄处下游2 cm、狭窄处下游3 cm、狭窄处下游4 cm)的iFRCT值。以有创性FFR≤0.80作为诊断冠状动脉缺血特异性狭窄的金标准,采用受试者工作特征(ROC)曲线分析不同测量位点iFRCT的诊断性能。采用Bland-Altman图和Spearman相关系数分析iFRCT与FFR间的相关性,采用组内相关系数(ICC)检验iFRCT观察者内和观察者间的一致性。结果狭窄处下游近端(最狭窄处下游约1 cm)iFRCT值诊断冠状动脉缺血特异性狭窄的性能优于其他测量位点,其阈值、曲线下面积、敏感度、特异度、准确度分别为0.91、0.87(95%CI:0.76~0.96)、82%(95%CI:48%~97%)、76%(95%CI:57%~88%)、77%(95%CI:63%~87%)。Bland-Altman分析结果显示狭窄处下游近端iFRCT与FFR之间的差异均值为0.07[95%一致限(LOA):0.06~0.09],r= 0.53(P<0.001)。狭窄处下游近端观察者内ICC为0.92(95%CI:0.85~0.95),r=0.85(P<0.001);观察者间ICC为0.85(95%CI:0.60~0.94),r=0.75(P<0.001)。结论以有创性FFR值为金标准,iFRCT对冠状动脉缺血特异性狭窄具有较好的诊断性能,最佳测量位点为狭窄处下游近端。

Objective To explore the influence of measurement sites on the diagnostic performance of coronary computed tomography angiography(CCTA)-derived instantaneous wave-free ratio(iFRCT)for coronary stenosis ischemia.Methods A total of 44 patients,including 27 males and 17 females aged from 44 to 83(59±90)years,who underwent coronary computed tomography angiography(CCTA)and invasive fractional flow reserve(FFR)in the Department of Radiology,Eastern Theater Command General Hospital from February 2009 to May 2018 were retrospectively collected.Based on CCTA images,iFRCT values at different locations(stenosis,proximal downstream of stenosis,2 cm downstream of stenosis,3 cm downstream of stenosis,and 4 cm downstream of stenosis)were calculated through fluid mechanics simulation.With invasive FFR≤0.80 as the reference standard,receiver operating characteristic(ROC)was used to analyze and evaluate the diagnostic performance of iFRCT in different sites.Bland-Altman and spearman correlation coefficient were used to analyze the consistency between iFRCT and invasive FFR.Intraclass correlation coefficient(ICC)and spearman correlation coefficient were used to test the repeatability of iFRCT.Results iFRCT values at the proximal downstream of the stenosis(approximately 1 cm downstream of the stenosis)was superior to other measurement sites in the diagnosis of coronary ischemic specific stenosis.The threshold,area under the curve,sensitivity,specificity and accuracy of iFRCT at the stenosis were 0.91,0.87(95%CI:0.76~0.96),82%(95%CI:48%~97%),76%(95%CI:57%~88%)and 77%(95%CI:63%~87%),respectively.Bland-Altman analysis showed that the mean differences between iFRCT and FFR at the proximal downstream of the stenosis was 0.07(95%LoA:0.06~0.09)and Spearman correlation coefficient was 0.53(P<0.001).At the proximal downstream of the stenosis,the intraobserver ICC of iFRCT was 0.92(95%CI:0.85~0.95),the correlation coefficient was 0.85(P<0.001);the interobserver ICC was 0.84(95%CI:0.60~0.94),correlation coefficient was 0.75(P<0.001),demonstrating good repeatability between iFRCT and FFR.Conclusion With the invasive FFR value as reference standard,iFRCT had a high diagnostic performance in detecting myocardial ischemia and the best measurement site was the proximal downstream of the stenosis.