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目的运用3.0 T磁共振扩散张量成像(MR-DTI)对兔心肌梗死(MI)后梗死区(CIZ)、边缘区(PIZ)及非梗死区(NIZ)的心肌微观结构进行检测,探索不同区域纤维重构的异质性。方法采用成年雄性兔分为正常组、假手术组及MI组。结扎冠状动脉左室支,建立兔MI模型。对离体心脏标本行3.0 T MR-DTI扫描,测量不同区域的各向异性分数(FA)值和平均扩散系数(MD)值,并行纤维素示踪成像和重建主本征矢量图,比较不同区域重构的差异。结果 MI后从CIZ向PIZ延展,再到NIZ代偿性重构,平均FA值呈上升趋势,平均MD值呈下降趋势。分别对MI后1 w、2 w、4 w、8 w及16 w组的三个区域进行两两比较,显示在不同时间点三个区域之间的FA值均有统计学差异。MD值在术后1 w组的CIZ与PIZ、PIZ与NIZ间,在术后2 w组三个区域之间,以及在术后8 w组的PIZ与NIZ间两两比较无统计学差异,其余比较均有差异。结论 MI从CIZ向PIZ延展,再到NIZ,重构程度呈渐变性,以CIZ最明显。FA值评估重构的异质性可能较MD值更为稳定可靠。
Objective To investigate the myocardial microstructure of myocardial infarction (CIZ), marginal zone (PIZ) and non-infarct zone (NIZ) after myocardial infarction (MI) in 3.0 T MR diffusion tensor imaging Heterogeneity of regional fiber remodeling. Methods Adult male rabbits were divided into normal group, sham operation group and MI group. Ligation of coronary artery left ventricular branch, the establishment of rabbit MI model. A 3.0 T MR-DTI scan of isolated heart specimens was performed to measure anisotropy scores (FA) and mean diffusivity (MD) values in different regions. Parallel Cellulose tracing imaging and reconstruction of the major eigenvectors were performed to compare different Differences in regional reconstruction. Results After MI extended from CIZ to PIZ and then to NIZ compensatory reconstruction, the average FA value showed an upward trend while the average MD value showed a downward trend. The comparison of the three regions of 1 w, 2 w, 4 w, 8 w and 16 w groups after MI showed statistically significant differences among the three regions at different time points. There was no significant difference in MD between the two groups of CIZ and PIZ, PIZ and NIZ in postoperative 1 w group, PIZ and NIZ in 3 w groups in postoperative 2 w group, PIZ and NIZ in postoperative 8 w group, The rest are more differences. Conclusion MI extends from CIZ to PIZ and then to NIZ, and the degree of remodeling is gradual with the most obvious CIZ. The heterogeneity of FA value assessment and reconstruction may be more stable and reliable than the MD value.