7T心脏磁共振组织追踪成像评估慢性心力衰竭大鼠的诊断价值

Diagnostic Value of 7T Cardiac Magnetic Resonance Tissue Tracking Imaging for Assessing Chronic Heart Failure in Rats

目的 探讨利用7T心脏磁共振组织追踪成像(CMR-TT)技术获得的二维(2D)与三维(3D)心肌应变参数对异丙肾上腺素(ISO)诱导的慢性心力衰竭(CHF)大鼠的诊断价值。方法 纳入20只无特定病原体(SPF)级健康雄性SD大鼠,随机分为对照组(n=8)和模型组(n=12)。采用连续14天皮下多点注射ISO溶液10 mg·kg^(-1)·d^(-1),正常饮食4周后制备CHF大鼠模型。造模结束后,对剩余大鼠即行7 T CMR电影序列扫描,采集数据后借助CVI42.0软件后处理分析比较两组大鼠左心室各心功能及心肌应变参数差异。扫描结束后处死大鼠,收集血清经酶联免疫吸附剂测定(ELISA)检测心肌肌钙蛋白I(cTn-I)及氨基末端脑钠肽前体(NT-pro BNP)含量,心肌组织行苏木精-伊红(HE)和马松(Masson)染色,以血清指标和病理染色结果为金标准,通过受试者工作特性(ROC)曲线评价各心肌应变参数的诊断价值,组内相关系数(ICC)和变异系数(CV)验证所得左心室心肌应变的可重复性。结果 模型组大鼠左心室舒张末期容积(LVEDV)、左心室收缩末期容积(LVESV)、cTn-I、NT-pro BNP较对照组增大(P<0.05),左心室射血分数(LVEF)、左心室每搏输出量(LVSV)、二维左心室整体径向应变(2D LVGRS)、二维左心室整体环向应变(2D LVGCS)、二维左心室整体纵向应变(2D LVGLS)则均有不同程度的降低(P<0.05),同时病理染色显示,模型组都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,以上结果提示CHF模型构建成功。ROC曲线显示2D左心室心肌应变参数的曲线下面积(AUC)均要高于3D应变参数,其中2D LVGRS和2D LVGCS的诊断价值最高,同时2D左心室应变参数的重复性均高于3D应变。结论 CMR-TT 2D心肌应变参数在诊断CHF上要整体优于3D心肌应变,且可重复性好。

Objective To investigate the diagnostic value of two-dimensional and three-dimensional myocardial strain parameters in rats with isoproterenol-induced chronic heart failure used by 7 T cardiac magnetic resonance tissue tracking imaging technique.Methods Twenty healthy male SD rats of specific pathogen-free class were included and randomly divided into control(n=8) and model groups(n=12).The chronic heart failure rat model was prepared by subcutaneous multipoint injection of ISO solution 10 mg·kg~(-1)·d~(-1) for 14 consecutive days and subsequent normal diet for 4 weeks.After the establishment of the model,7 T CMR cine sequence scans were performed immediately,and the post-processing software CVI42.0 was used to analyze and compare the differences in each LV function and myocardial strain parameters between the two groups of rats.At the end of the scan,enzyme-linked immunosorbent assay was performed to detect cardiac troponin I and amino-terminal brain natriuretic peptide precursor levels in serum,and myocardial tissue was stained with hematoxylin-eosin and Masson staining.The diagnostic value of each myocardial strain parameter was evaluated by receiver operating characteristic curves,using serum indexes and pathological staining as the gold standard.Intraclass correlation coefficients and coefficients of variation was used to verify the reproducibility of the left ventricular myocardial strain.Results In the model group,left ventricular end-diastolic volume,left ventricular end-systolic volume,cardiac troponin I and amino-terminal brain natriuretic peptide precursor levels were increased compared with the control group(P< 0.05),while left ventricular ejection fraction,left ventricular stroke volume,2D left ventricular global radial strain,2D left ventricular global circumferential strain,and 2D left ventricular global longitudinal strain were decreased to different degrees(P< 0.05).At the same time,pathological staining showed that the model groups all exhibited myocardial fiber arrangement disorder,degeneration,necrosis,inflammatory cell infiltration,and interstitial fibrosis.The above results suggested that the CHF model was successfully constructed.The receiver operating characteristic curves showed that the area under the curves of 2D LV myocardial strain parameters were all higher than those of 3D strain parameters,with 2D LVGRS and 2D LVGCS having the highest diagnostic value,while the repeatability of 2D LV strain parameters were all higher than that of 3D strain.Conclusion CMR-TT 2D myocardial strain parameters were overall superior and reproducible to 3D myocardial strain in the diagnosis of CHF.