心脏磁共振组织追踪2D与3D应变评估实验性自身免疫性心肌炎模型大鼠的诊断价值及可重复性研究

  目的  探讨心脏磁共振组织追踪(cardiac magnetic resonance tissue tracking, CMR-TT)二维(two-dimensional, 2D)与三维(three-dimensional, 3D)应变对实验性自身免疫性心肌炎大鼠的诊断价值及其可重复性。  方法  将20只Lewis大鼠随机等分为模型组和对照组，大鼠足垫皮下注射猪心肌肌凝蛋白以制备自身免疫性心肌炎动物模型，在初次注射后第35天进行7.0T CMR电影序列扫描，心脏专用后处理软件分析左心室心功能及整体应变。磁共振扫描完成后处死大鼠，取心肌组织行HE和Masson染色，以病理结果为金标准，通过受试者工作特性(ROC)曲线评价各应变参数的诊断价值，各应变值的重复性检验采用组内相关系数(ICC)、变异系数(CV)、Bland-Altman图分析。  结果  病理学发现对照组心肌细胞形态结构未见明显异常改变，模型组所有大鼠均感染心肌炎，表现为心肌纤维排列紊乱、变性、坏死、炎细胞浸润、间质纤维化，造模成功。ROC曲线显示2D应变参数诊断心肌炎的价值高于3D应变参数，2D整体环向应变(global circumferential strain, GCS)、2D整体径向应变(global radial strain, GRS)、2D整体纵向应变(global longitudinal strain, GLS)、3D GLS、3D GCS、3D GRS的曲线下面积(AUC)分别为0.96、0.95、0.90、0.87、0.85、0.77；观察者内和观察者间3D应变重复性(ICC在0.421~0.79)均低于2D应变(ICC在0.893~0.986)。  结论  CMR-TT 2D应变参数在心肌炎诊断价值以及心肌形变分析中的可行性、可重复性方面均优于3D应变参数。

Diagnostic Values and Reliability of Cardiac Magnetic Resonance Tissue Tracking 2D and 3D Strain Assessments for Experimental Autoimmune Myocarditis in Rats

  Objective  To determinethe diagnostic valuesand reliabilityof cardiac magnetic resonance tissue tracking (CMR-TT) derived two-dimensional(2D) and three-dimensional(3D) strains in assessing experimental autoimmunity myocarditis (EAM) in rats.  Methods  20 Lewis rats were randomly divided into model and control groups. The animal model of autoimmune myocarditis was induced by injecting porcine cardiac myosin into the footpads of the rats.On day 35, all of the rats were examined using the 7.0T CMR cine scan. The cardiac function and global strain of the left ventricular of the rats were analyzed with specific cardiac post-processing. The rats were then sacrificed and myocardial samples were taken and stained with HE and Masson. The diagnostic values of the strain parameters were assessed by receiver operating characteristic (ROC) curves with the pathological results as diagnostic criteria.The reliability of the strain parameters were tested using interclass correlation coefficient (ICC), coefficients of variation (CV) and Bland-Altman.  Results  No abnormal pathological changes in myocardial cells were found in the control group. Myocarditis was successfully induced in all of the rats in the model group, showing myocardial fiber arrangement disorder, degeneration, necrosis, inflammatory cell infiltration and interstitial fibrosis. The ROC showed that 2D global strain parameters possessed higher diagnostic values than 3D strain parameters. The 2D had an area under the curve (AUC) of 0.96 in global circumferential strain (GCS), 0.95 in global radial strain (GRS), and 0.90 in global longitudinal strain (GLS), compared with 0.87 GCS, 0.85 GRS, and 0.77 GLS in the 3D, respectively.The reliability of the 2D strain parameters was high, except for inter-observer 2D GRS(ICC=0.893). The 3D strain parameters had lower reliability (ICCs:0.421-0.79) than the 2D strain parameters (ICCs:0.893-0.986).  Conclusion  The diagnostic values of 2D strain parameters are higher than 3D strain parameters in diagnosing myocarditis.