核素显像心肌灌注缺损与CTCA冠状动脉不同狭窄程度的关系分析

目的通过分析核素显像心肌灌注缺损与CTCA示冠状动脉（简称冠脉）不同狭窄程度间的关系，探讨和评价CTCA预测心肌灌注缺损的诊断效能。方法回顾性分析同期行CTCA和MPI患者478例。按目测法将CTCA所示冠脉管腔狭窄程度分成无狭窄、轻度狭窄、中度狭窄、重度狭窄和管腔闭塞，将MPI结果分成灌注正常和灌注缺损，分别在病例和血管水平统计各组灌注缺损的发生率。以MPI为参考标准，将CTCA预测心肌灌注缺损的冠脉狭窄程度判定界值设为≥50％或≥75％，在病例水平和血管水平上确定该方法的诊断效能。计数资料统计分析采用χ^2检验、χ^2分割法和Fisher确切概率法。结果478例患者中58例出现MPI灌注缺损。无论按病例水平还是血管水平分析，各组灌注缺损发生率有随冠脉狭窄程度增加而升高趋势（χ^2=116．62和483．83，P均〈0．05）。在病例水平上分析，当判定界值为≥50％或≥75％时，CTCA预测心肌灌注缺损的诊断灵敏度、特异性、阳性预测值、阴性预测值、准确性分别为62．1％（36／58）或34．5％（20／58）（χ^2=8．84，P〈0．05）、84．5％（355／420）或97．1％（408／420）（χ^2=40．16，P〈0．05）、35．6％（36／101）或62．5％（20／32）（χ^2=7．19，P〈0．05）、94．2％（355／377）或91．5％（408／446）（χ^2=2．18，P〉0．05）、81．8％（391／478）或89．5％（428／478）（χ^2=11．66，P〈0．05）；在血管水平上分析，判定界值为≥50％或≥75％时，CTCA预测心肌灌注缺损的诊断灵敏度、特异性、阳性预测值、阴性预测值、准确性分别为58．8％（40／68）或30．9％（21／68）（χ^2=10．73，P〈0．05）、95．9％（1768／1844）或99．0％（1826／1844）（χ^2=36．72，P〈0．05）、34．5％（40／116）或53．8％（21／39）（χ^2=4．59，P〈0．05）、98．4％（1768／1796）或97．5％（1826／1873）（χ^2=4．14，P〈0．05）、94．6％（1808／1912）或96．6％（1847／1912）（χ^2=10．31，P〈0．05）。结论心肌灌注缺损的发生率随冠脉狭窄程度增加有升高趋势。CTCA预测心肌灌注缺损的诊断特异性和阴性预测值较佳。当判定界值为≥75％时，其阳性预测值较判定界值为≥50％时有明显提高。

The relationship between perfusion defects on myocardial SPECT and stenotic severity on CT coronary angiography

Objective To evaluate the diagnostic performance of CTCA in predicting myocardial perfusion defects through comparative analysis between MPI defects and severity of coronary stenosis on CTCA.Methods Four hundred and seventy-eight patients who underwent CTCA and 99Tcm-MIBI MPI in the same period were analyzed retrospectively.According to the severity of coronary stenosis judged by visual evaluation of the vessel diameter,the patients were divided into five groups:no stenosis,mild stenosis,moderate stenosis,severe stenosis and total occlusion.MPI results were classified as negative or positive for perfusion defects,and the prevalence of perfusion defects in every group was calculated per-patient and per-vessel basis.The cut-off of stenotic severity for predicting myocardial perfusion defects was designated as 50％ or 75％,with MPI as standard reference.True positive,true negative,false positive and false negative statistics were thus determined separately on patient and vessel basis.The diagnostic performance for CTCA were calculated and compared.Pearson Chi-square and its partition tests or Fisher exact test were used to compare ordinal variables.Results Fifty-eight patients showed myocardial perfusion defects.Either by patientbased or vessel-based analysis,the prevalence of myocardial perfusion defects showed an increasing trend with greater coronary artery stenosis in each group,and there were statistical differences among them (x2 =116.62 and 483.83,both P ＜ 0.05).On patient-based analysis,sensitivity ( SN),specificity ( SP),positive predictive value( PPV),negative predictive value(NPV) and accuracy (AC) for CTCA predicting myocardial perfusion defects were 62.1 ％ ( 36/58 ) and 34.5％ ( 20/58 ) (x2 =8.84,P ＜ 0.05 ),84.5％(355/420) and 97.1％ (408/420) (x2 =40.16,P ＜0.05),35.6％ (30/101) and 62.5％ (20/32) (x2 =7.19,P＜0.05),94.2％ (355/377) and 91.5％ (408/446) (x2 =2.18,P ＞0.05),81.8％ (391/478)and 89.5 ％ (428/478) (x2 =11.66,P ＜ 0.05 ) when the cutoff was set to 50％ and 75％,respectively.On vessel-based analysis,the SN,SP,PPV,NPV and AC for CTCA predicting myocardial perfusion defects were 58.8％ (40/68) and 30.9％ (21/68) (x2 =10.73,P ＜ 0.05),95.9％ (1768/1844) and 99.0％ (1826/1844) (x2 =36.72,P ＜ 0.05 ),34.5％ (40/116) and 53.8％ (21/39) (x2 =4.59,P ＜0.05 ),98.4％ (1768/1796) and 97.5％ ( 1826/1873 ) (x2 =4.14,P ＜ 0.05 ),94.6％ ( 1808/1912 ) and 96.6％ ( 1847/1912 ) (x2 =10.31,P ＜ 0.05 ),respectively.Conclusions The prevalence of myocardial perfusion defects correlates positively with the severity of coronary stenosis seen on CTCA.CTCA may predict perfusion defects with high SP and NPV.However,the PPV of CTCA in predicting myocardial perfusion defects is poor when the stenosis cut-off is set at 50％.It is significantly improved when the cutoff value is set at 75 ％.