7.0T心脏MR成像在肺动脉高压大鼠模型右心功能评估中的作用

Right ventricular function evaluation by 7.0T cardiac MRI in a rat model of pulmonary artery hypertension

目的:基于7.0T心脏磁共振成像(cardiac magnetic resonance,CMR)观察肺动脉高压(pulmonary artery hypertension,PAH)大鼠肺动脉径线和心脏功能的变化。方法:选用36只雄性SD大鼠(随机分为6组,每组6只)采用低氧建立PAH大鼠模型。于未缺氧时(基线)及缺氧后第1、2、3、4、5周利用MR(Bruker BioSpec 7.0T)进行心脏成像,分别测量主肺动脉(main pulmonary artery,MPA)、右肺动脉(right pulmonary artery,RPA)、左肺动脉(left pulmonary artery,LPA)直径,并计算其与同层面升主动脉(ascending aorta,AA)直径之比(MPA/AA、RPA/AA、LPA/AA);四腔心位右室舒张末期最大径线(right ventricular end-diastolic maximum diameter,dRVmax)与左室舒张末期最大径线(left ventricular end-diastolic maximum diameter,dLVmax)之比(d RVmax/dLVmax),右室舒张末容积(right ventricular end diastolic volume,RVEDV),右室收缩末容积(right ventricular end systolic volume,RVESV),进而计算右室射血分数(right ventricular ejection fraction,RVEF);每只大鼠均行右心导管术获取右室收缩压(right ventricular systolic pressure,RVSP)。采用SPSS 24.0统计软件,应用独立样本t检验及ANOVA分析比较不同时间点上述各参数的差异,采用Pearson相关性分析评价各参数与RVSP的相关性。结果:造模后第1周大鼠RVSP即较基线升高[(29.92±1.94)mmHg vs.(41.55±3.14)mmHg,P<0.01],后每周逐步升高,MPA、dRVmax/dLVmax及RVESV、RVEDV逐渐增大(P<0.01),RVEF在缺氧第2周显著降低(P<0.01)。MPA/AA、dRVmax/dLVmax、RVEF与RVSP具有较好的相关性(r分别为0.573、0.700、-0.760,P均<0.01)。结论:7.0T CMR可敏感地观察到PAH大鼠病程进展中肺动脉及右心形态功能的改变,为研究PAH的演变机制打下基础。

Objective:To observe the evolution of pulmonary artery diameters and cardiac functional changes in a rat model of pulmonary artery hypertension(PAH)using 7.0 T cardiac magnetic resonance(CMR). Methods:A rat model of PAH was established by hypoxia. A total of 36 rats were divided into 6 groups on average(baseline,hypoxia at 1 st,2 nd,3 rd,4 th,and 5 thweeks;n=6). CMR was performed every week by Bruker BioSpec 7.0 T. The diameters of the main pulmonary artery(MPA),right pulmonary artery(RPA),left pulmonary artery(LPA),right ventricular end-diastolic maximum diameter(dRVmax),left ventricular end-diastolic maximum diameter(dLVmax),right ventricular end-diastolic volume(RVEDV)and right ventricular end-systolic volume(RVESV)were measured on MR images;ratio of dRVmaxto dLVmax(dRVmax/dLVmax),ratio of the main pulmonary artery to the ascending aorta(MPA/AA,RPA/AA,and LPA/AA),right ventricular and left ventricular ejection fraction(RVEF)were calculated. Right ventricular systolic pressure(RVSP)was obtained by right heart catheterization after CMR imaging for each rat. Comparison of above-mentioned parameters at different time points was calculated by t test and ANOVA analysis(SPSS 24.0). Pearson correlation analysis was used to evaluate the correlation between above-mentioned parameters and RVSP. Results:The RVSP in model rats at the first week increased significantly compared with the baseline[(29.92 ± 1.94)mmHg vs.(41.55 ± 3.14)mmHg,P<0.01],and then gradually increased from the first week to the fifth(P < 0.01). MPA,dRVmax/dLVmax,RVESV,and RVEDV gradually increased(P<0.01). RVEF decreased significantly in the 2 nd week of modeling(P < 0.01). There were moderate correlations between the MPA/AA,dRVmax/dLVmax,RVEF and RVSP in model rats(r=0.573,r=0.700,r=-0.760,all P < 0.01). Conclusion:7.0 T CMR can sensitively observed changes in pulmonary artery diameter and right ventricular function during the progression of PAH rats,which lays a foundation for studying the evolutionary mechanism of PAH.