心脏磁共振组织追踪技术评估冠心病心肌梗死的诊断价值

目的探讨心脏磁共振组织追踪技术(cardiovascular magnetic resonance tissue tracking technology,CMR-TT)与冠心病患者左心功能相关性及定量化评价心肌梗死的诊断价值。材料与方法对23例冠心病患者和16名健康志愿者进行3.0 T SSFP电影序列以及对比延迟增强扫描,用CVI42软件测量心功能,并使用组织追踪技术对左心室整体和节段的应变进行分析,得到心肌径向、周向、纵向三个方向CMR-TT 3D应变参数值。对上述参数值进行组间均值比较、组内相关系数(ICC)分析、Pearson相关性分析、Logistic回归模型、受试者工作特性(receiver operating characteristic,ROC)曲线分析。结果左心室整体径向应变(radial strain,RS)(ICC=0.944)、周向应变(circumferential strain,CS)(ICC=0.988)、纵向应变(longitudinal strain,LS)(ICC=0.987)均表现较好的可重复性。冠心病组左心室整体的径向应变、周向应变、纵向应变低于健康人组(30.35%±17.26%和45.46%±8.90%、-13.92%±5.7 7%和-1 9.3 4%±2.3 0%、-11.3 0%±4.7 5%和-1 6.5 4%±2.4 0%,P值均0.01)。左心室射血分数与径向应变呈强相关(r=0.774,P0.001),与周向应变呈强相关(r=0.778,P0.001),与纵向应变呈极强相关(r=0.802,P0.001)。冠心病组延迟强化(late gadolinium enhancement,LGE)阳性心肌节段径向应变、周向应变、纵向应变峰值低于LGE阴性心肌节段(9.95%和41.42%,-7.67%和-17.2%,-6.68%和-13.83%,P值均0.01)。心肌径向应变(AUC=0.914)、周向应变(AUC=0.911)在诊断心肌节段梗死中具有较高的诊断价值,纵向应变(AUC=0.819)具有一定的诊断价值;当心肌径向应变截断值为16.83%时,诊断准确度较高(Youden指数=0.7399);当周向应变截断值为-11.44%时,诊断准确度较高(Youden指数=0.7511);纵向应变在截断值为-9.41%时,诊断准确度较低(Youden指数=0.5552)。当使用径向应变和周向应变联合诊断冠心病心肌节段梗死时,AUC和特异度较各指标独立诊断时提高,在联合诊断时纵向应变无预测意义。结论心脏磁共振组织追踪技术在临床应用中具有较好的可行性及可重复性;径向应变、周向应变、纵向应变与冠心病左心室射血分数具有较强的相关性;径向应变、周向应变在诊断冠心病心肌节段梗死的诊断价值较高,纵向应变诊断价值有限。当使用径向应变和周向应变两项指标联合诊断时可提高诊断效能。这提示CMR-TT的应变分析在无需对比剂的情况下识别冠心病心肌梗死节段具有潜在的临床诊断价值。

Clinical evaluation of cardiac magnetic resonance tissue tracking technology for coronary heart disease patients with myocardial infarction

Objective: Echocardiography and cardiac magnetic resonance can measure myocardial motion and deformation noninvasively. The purpose of this study was to investigate the clinical value of cardiac magnetic resonance tissue tracking technology (CMR-TT) in assessing left ventricular function in patients with coronary artery disease (CAD) and in correctly diagnosing myocardial infarction. Materials and Methods: Twenty three patients with coronary artery disease and 16 healthy volunteers underwent 3.0 T CMR, including CMR cine and late gadolinium enhancement. We use CVI42 software to measure heart function. The cardiac function was measured with CVI42 software and the global or segmental strain of left ventricle was analyzed using tissue tracking technology to obtain myocardial 3D strain parameter values in all directions. The mean value of the above parameters were compared among groups,ICC analysis,Pearson correlation analysis,Logistic regression model and receiver operating characteristic analysis(ROC analysis).Results:The overall left ventricular radial strain(ICC=0.944),circumferential strain(ICC=0.988)and longitudinal strain(ICC=0.987)showed good repeatability.The radial strain, circumferential strain and longitudinal strain in the left ventricle in the CAD group were significantly lower than those in the healthy group (30.35%±17.26% vs 45.46%±8.90%, -13.92%±5.77% vs -19.34%±2.30%, -11.30%±4.75% vs -16.54% ± 2.40%, P<0.01). Left ventricular ejection fraction was strongly correlated with radial strain (r= 0.774, P<0.001) and strongly correlated with circumferential strain (r=0.778, P<0.001) and strongly correlated with longitudinal strain (r=0.802, P<0.001). The peak values of radial strain, circumferential strain and longitudinal strain of LGE-positive myocardial segments in coronary heart disease group were lower than those in LGE-negative myocardial segments (9.95% vs 41.42%, -7.67% vs -17.2% -6.68% vs -13.83%, P<0.01). Myocardial radial strain (AUC=0.914) and circumferential strain (AUC=0.911) have high diagnostic value in the diagnosis of myocardial infarction. When the cut-off value of myocardial radial strain was 16.83%, the diagnostic accuracy was high (Youden index=0.7399). When the circumferential strain cut-off is -11.44%, the diagnostic accuracy is high (Youden index=0.7511). Longitudinal strain with a cut-off value of -9.41%, diagnostic accuracy is low (Youden index=0.5552).When we use the radial strain and circumferential strain combined diagnosis of myocardial infarction of coronary heart disease, AUC, sensitivity and specificity than independent diagnosis of each index increased. Conclusions: Cardiac magnetic resonance tissue tracking has good feasibility and repeatability in clinical application. Radial strain, circumferential strain and longitudinal strain have a strong correlation with left ventricular ejection fraction of coronary heart disease. Radial strain and circumferential strain have higher diagnostic value in the diagnosis of myocardial infarction in coronary heart disease. When we use these two indicators combined diagnosis can improve diagnostic performance.This suggests that CMR-TT strain analysis has potential clinical value in identifying myocardial infarction segments without coronary contrast.