基于双源CT双能量成像的犬无复流心肌活性实验研究

Myocardial viability of myocardial ischemic canine with no-reflow:an experimental study based on dual-source computed tomography

目的：通过双源 CT（DSCT）心肌灌注扫描观察心肌缺血无复流动物模型的 CT 表现，初步探讨双能量心肌灌注扫描在评估无复流心肌中的应用价值。方法：通过球囊堵塞（60～90 min）加微粒明胶海绵栓塞犬前降支中远段，建立犬心肌缺血无复流模型（n＝6），采用 DSCT 进行首过及3、5、10、15 min 多期延迟心肌灌注扫描，观察梗死区 CT 表现，完成检查后取犬心脏标本行氯化三苯基四氮唑（2，3，5-TTC）染色及 HE 染色，与 DSCT 检查结果进行对照。结果：2只犬在介入手术过程中死亡，4只犬完成模型建立。扫描过程中犬平均心率为135 bpm。DSCT 扫描均可见心肌梗死区 CT 值较正常心肌减低，首过及多期延迟扫描呈固定灌注减低表现，TTC 染色显示梗死区范围与 DSCT 所见相符，HE 染色梗死中心区和边缘区均可见心肌坏死。在不同能量的 DSCT 图像中，100 kV 灌注图像对心肌密度区分能力最强，140 kV 灌注图像噪声最低，而双能量融合灌注图像则在实现密度差异的前提下保证了较低的噪声。结论：DSCT 可以较好地在快心率状态下显示心肌，心肌灌注扫描显示固定灌注减低可能与心肌完全坏死有关。

Using dual-source computed tomography （DSCT）myocardial perfusion scan to observe imaging manifestations of myocardial ischemia with no-reflow in canine models,and explore its usage in analyzing no-reflow myocar-dium.Methods：Canine models （n=6）of myocardial ischemia with no-reflow were established by blocking the mid-distal segment of left anterior descending artery using a balloon and gelatin sponge particles.DSCT was performed with first-pass myocardial perfusion and multi-phase delay scan （3min,5min,10min,15min）to observe the CT manifestations of the infarct segments.The specimens of canine heart were taken after DSCT scan and later stained with triphenyl tetrazolium chloride （TTC）and hematoxylin eosin （HE）.The results were compared with the CT scan.Result：Two canine models died during surgery;four canine models were successfully established.The average heart rate was 135bpm.DSCT scan showed that the CT attenuation of infarct segments was significantly lower than that of the normal segments.The infarct segments showed fixed hypoperfusion in the first-pass and during the multi-phase delay scan.The area of infarct segments was similar to that of TTC staining.In addition,the HE staining showed myocardial necrosis in the central and peripheral areas in the infarct segments.100kV images were best at differentiating myocardial attenuation;140kV images had the best quality with mini-mal noise;and the 140kV/100kV fusion images could maintain low noise while having sufficient image quality.Conclusion：DSCT can clearly demonstrate myocardial perfusion with fast heart rate.Fixed hypoperfusion during DSCT myocardial per-fusion scan may be associated with total myocardial necrosis.