动态CT心肌灌注成像评价猪冠状动脉微循环障碍模型的实验研究

目的:探讨动态CT心肌灌注成像(CT-MPI)定量指标评价猪冠状动脉微循环障碍(CMD)模型的价值。方法:10只实验中华小型猪,麻醉后经股动脉选择性插管,通过导丝缓慢注入左前降支远段1 ml微球混合液(含微球0.5×10⁵/0.5 ml),建立CMD模型。分别于建模前60 min及建模后10 min行CT-MPI静息态和负荷态扫描。测量CT-MPI的定量指标,包括心肌血流量(MBF)、心肌血容量(MBV)。以实验猪建模前后CT-MPI指标的变化为自身参照标准,采用配对样本t检验比较建模前后静息和负荷状态下MBF、MBV的差异。之后处死动物并行病理检查证实CMD心肌节段。结果:8只猪完成实验(2只猪于建模时死亡)。CMD区静息MBF、MBV分别为(98.6±20.9)ml·100 ml^-1·min^-1、(9.0±2.8)ml/100 ml;负荷MBF、MBV分别为(87.6±14.6)ml·100 ml^-1·min^-1、(8.0±1.8)ml/100 ml。CMD区静息和负荷MBF及MBV与非CMD区比较均减低(P<0.001)。HE染色低倍镜下显示损伤心肌与正常心肌并存,高倍镜下显示心肌细胞质黏附,嗜酸性粒细胞增多,心肌细胞排列疏松,细胞核部分出现皱缩以及心肌细胞间质水肿。结论:本研究通过动态CT-MPI评价CMD动物模型,表明CMD心肌节段在静息和负荷状态下的MBF值和MBV值均较造模前明显减低,MBF、MBV变化值可作为动态CT-MPI评价CMD的定量指标。

The evaluation on coronary microcirculation disorder by dynamic CT myocardial perfusion imaging: an experimental study

Objective To explore the value of quantitative parameters of dynamic CT myocardial perfusion imaging(CT-MPI)in evaluating coronary microcirculation dysfunction(CMD)in a porcine model.Methods Ten Chinese miniature pig age of 5 to 8 months were randomly selected in this experimental study.After anesthesia,a micro guide wire was introduced via a percutaneous direct puncture through superficial femoral artery.Then 1 ml of microsphere mixture,which contained 0.5×105/0.5 ml of microsphere,was slowly injected into the distal of anterior descending artery to establish a CMD animal model.Resting and stress CT-MPI were performed 60 min before and 10 min after CMD.The quantitative parameters of dynamic CT-MPI including myocardial blood flow(MBF)and myocardial blood volume(MBV)were measured.Using the changes of MBF and MBV before and after CMD as self-references,a paired-sample t test was used to compare the differences of MBF and MBV of resting and stress CT-MPI before and after CMD.The animals were sacrificed for myocardial histopathological examination after the imaging examination.Results Of the 10 experimental animals,two pigs died,and CMD model was successfully established in the other 8 pigs.The MBF and MBV of CMD myocardial segments in resting CT-MPI were(98.6±20.9)ml·100 ml^-1·min^-1 and(9.0±2.8)ml/100 ml,respectively.The MBF and MBV of CMD myocardial segments in stress CT-MPI were(87.6±14.6)ml·100 ml^-1·min^-1 and(8.0±1.8)ml/100 ml,respectively.Both of the MBF and MBV of CMD myocardial segments in resting CT-MPI were significantly reduced,compared with those of the normal myocardial segments(P<0.001).HE staining showed myocardial infarcts interspersed with normal myocardial foci at low magnification.Pathological alterations,including myocardial cytoplasm cohesion,eosinophil level variations,stripe disappearance,nuclear relocation,and cardiomyocyte interstitial edema,were displayed at high-magnification by microscopy.Conclusions In this experimental study of CMD animal models,MBF and MBV of dynamic CT-MPI were significantly decreased in CMD myocardial segments compared with those before CMD.The changes of MBF or/and MBV can be used as dynamic CT-MPI quantitative parameters for evaluation of CMD.