目的 应用基于心脏磁共振成像(MRI)电影序列的特征追踪技术分析急性心肌梗死患者左心室心肌应变,探索其与急性心肌梗死透壁程度的关系,及急诊经皮冠状动脉介入治疗(PCI)术后心肌应变演变规律.方法 入组74例急性ST段抬高型心肌梗死(STEMI)患者,均于急性心肌梗死12 h内接受急诊PCI,术后2～5 d,行心电门控稳态自由进动序列扫描采集电影序列图像,同时行钆对比剂延迟强化,得到短轴强化序列图像.其中20例3～5月后复查MRI.应用TomTec 2D CPA软件分析电影序列,得到局部心肌应变指标,(包括各节段内膜圆周、径向、纵向应变峰值),和整体心肌应变指标(包括整体圆周、径向、纵向应变值),应用Segment分析软件计算延迟强化序列各个节段心肌梗死透壁程度.结果 本研究74例STEMI患者,梗死面积为(11.81±7.28)％.分析得到537个无梗死节段,425个非透壁梗死节段,182个透壁梗死节段.圆周应变峰值基底段无梗死节段(-23.90±10.92)％、非透壁梗死节段(-18.94±10.51)％、透壁梗死节段(-14.24±9.05)％,两两比较发现,无梗死节段指标(取绝对值)显著高于非透壁梗死节段(P=0.000),非透壁梗死节段指标显著高于透壁梗死节段(P=0.016).圆周应变峰值中间段无梗死节段(-22.13±9.98)％、非透壁梗死节段(-17.47±8.72)％、透壁梗死节段(-12.71±8.92)％,两两比较发现,无梗死节段指标(取绝对值)显著高于非透壁梗死节段(P=0.000),非透壁梗死节段指标显著高于透壁梗死节段(P=0.000).圆周应变峰值心尖段无梗死节段(-22.46±10.31)％、非透壁梗死节段(-19.51±12.49)％、透壁梗死节段(-13.81±11.13)％,两两比较发现,透壁梗死节段指标(取绝对值)显著低于无梗死节段(P=0.000)与非透壁梗死节段(P=0.001),但无梗死节段与非透壁梗死节段指标比较,差异无统计学意义.纵向应变峰值在基底段与中间段,无梗死节段、非透壁梗死节段及透壁梗死节段指标比较,差异无统计学意义;但心尖段三个阶段指标分别是(-20.26±12.42)％,(-14.82±11.29)％,(-11.94±9.73)％,两两比较发现,无梗死节段指标(取绝对值)显著高于非透壁梗死节段(P=0.000),非透壁梗死节段显著高于透壁梗死节段(P=0.043).径向应变峰值在基底段无梗死节段(31.92±17.47)％ 与非透壁梗死节段(22.35±18.57)％ 比较,差异有统计学意义(P=0.000),与透壁梗死节段(17.78±16.24)％比较,差异有统计学意义(P=0.000),但非透壁梗死节段与透壁梗死节段比较,差异无统计学意义.径向应变峰值在中间段无梗死节段(32.13±16.37)％、非透壁梗死节段(25.20±15.85)％、透壁梗死节段(15.20±10.48)％,两两比较发现,无梗死节段指标显著高于非透壁梗死节段(P=0.000),非透壁梗死节段指标显著高于透壁梗死节段(P=0.000).径向应变峰值心尖段无梗死节段(27.42±14.94)％ 与非透壁梗死节段(20.51±15.43)％ 比较,差异有统计学意义(P=0.001),与透壁梗死节段(16.59±11.84)％ 比较,差异有统计学意义(P=0.000),但非透壁梗死节段与透壁梗死节段比较,差异无统计学意义.20例患者PCI术后无梗死节段、非透壁梗死节段、透壁梗死节段圆周应变、纵向应变及径向应变达峰值均较急性心肌梗死时有升高趋势.其中非透壁梗死节段圆周应变(取绝对值)及纵向应变(取绝对值)较PCI术前升高[(-16.88±9.92)％比(-19.46±11.31)％,P=0.018;(-12.02±9.46)％比(-16.67±11.29)％,P=0.000];透壁梗死节段圆周应变(取绝对值)及径向应变较PCI术前升高[(-13.83±9.47)％ 比(17.20±10.63)％,P=0.035;(18.36±12.85)％ 比(24.55±14.81)％,P=0.001],差异均有统计学意义.结论 急诊PCI术后STEMI患者,在急性期局部心肌应变在无梗死节段、非透壁梗死节段、透壁梗死节段之间有差别.PCI术后3～5个月,非透壁梗死节段圆周应变及纵向应变较急性期时改善,而透壁梗死节段圆周应变及径向应变改善.心脏磁共振成像特征追踪技术与钆对比剂延迟技术相结合,可从功能学和组织学特征两方面对急性心肌梗死心肌损伤综合评估.%Objective The left ventricular myocardial strain of acute myocardial infarction on cardiac magnetic resonance cine imaging was measured by feature tracking technique. The relationship between left ventricular myocardial strain and the transmural extent of Myocardial Infarction was evaluated. Methods 74 patients with acute ST segment elevation myocardial infarction were included. All theses patients received primary PCI within 12 hours. After 2 to 5 days. ECG gated steady-state free precession sequences were collected. Gadolinium contrast enhanced imaging was performed on short axis. 20 patients repeated same scan after 3 to 5 months. TomTec 2D CPA and Segment software were used to analyze the images. The peak values of the regional myocardial strain indexes. The transmural extent of myocardial infarction of segment in left ventricular was measured. Results There was no significant difference of longitudinal strain in non-infarction,non-transmural infarction and transmural infarction segments at the basal and middle segments. The circumferential strain peak and the radial strain peak of non-transmural infarction segments were lower than those of the non-infarction segments. The circumferential strain of transmural infarction segments were the lowest(basal level:-14.24％±9.05％,P<0.05;middle level:-12.71％±8.92％,P<0.05;apical level:-13.81％±11.13％, P<0.05). GLS was improved while LVDd was increased when compared the acute phase of myocardial infarction to that of 3-5 months after primary PCI. The circumferential strain and longitudinal strain of the non-transmural infarction segments was improved. The circumferential strain and radial strain of the transmural infarction segments 3-5 months later was improved as compared to the acute phase. Conclusions There was differences in myocardial strain in non-infarction,non-transmural infarction and transmural infarction segments from patients with acute ST segment elevation myocardial infarction who had accepted primary PCI. The circumferential strain and longitudinal strain of the non-transmural infarction segments were improved after 3-5 months. The circumferential strain and radial strain of the transmural infarction segments after 3-5 months was improved as compared to the acute phase. Cardiac Magnetic resonance could combine feature tracking technique with gadolinium contrast delayed enhancement technique,giving both function and tissue characteristic evaluation to the myocardial damages after acute myocardial infarction.
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