急性心肌梗死的CT灌注实验研究

An experimental study on the acute myocardial infarction with CT perfusion scans

目的 探讨CT灌注扫描检测急性心肌梗死病灶的可靠性 ;定量研究急性梗死灶伽玛(γ)曲线的参数特征 ,以期指导临床对于冠心病及心肌梗死的分析、诊断。方法 使用ImatronC 15 0型电子束CT(EBCT) ,灌注扫描程序 ,扫描对比剂流动模型 ,观察拟合的曲线以及在不同灌注量中的变化 ;选取 6只健康家犬 ,麻醉后经开胸手术 ,结扎左冠状动脉前降支和旋支分支 ,使左心侧壁部分梗死。通过EBCT灌注扫描 ,观察正常和梗死区的形态及其灌注曲线变化 ,分析正常和梗死区的曲线特征和各参数 ,经统计学处理 ,提出其差异和鉴别点。有 2只同时经单光子发射体层计算机(SPECT)扫描 ,所有标本经氯化三苯基四氮唑 (TTC)染色处理 ,与扫描图像比较 ,并通过光学显微镜和电子显微镜检查证实。结果 不同灌注量的模型扫描曲线上升斜率不同 ;犬心肌的正常灌注曲线为一上升稍快 ,继之平缓下降的γ 曲线 :其上升时间约 10～ 13s,上升CT值约 34～ 37HU ,峰值CT值约 70～ 81HU。而梗死心肌的上升时间延长 ,平均 19 9s左右 ,上升CT值和峰值CT值降低 ,平均分别为 2 0 0和 5 3 8HU ,与正常心肌比较差异有显著性意义 (P <0 0 5 )。结论 正常与梗死心肌的灌注曲线有显著性差异 ,CT灌注扫描能够检测。

Objective To determine the reliability of CT perfusion scans and its parameters of γ-variate curve in evaluating the acute myocardial infarction for clinical reference of diagnosis on coronary artery disease and myocardial infarction. Methods Imatron C-150 electron beam CT (EBCT) were used to scan a hydrodynamic model which could mimic a change of contrast medium by intravenous injection in vivo. Then 6 adult canines were employed in the experiment with thoracic operation, and branches of the anterior descending and circumflex of left coronary arteries (LCA) were ligated so that myocardial infarction was made out. After intravenous administration of contrast medium, the hearts were scanned with perfusion EBCT and γ-variate curves were manifested. Some heterogeneities and differentiations between the normality and the infarctions were put forward when the parameters of all these curves were analyzed and statistically processed. Two myocardial infarctions were also verified by SPECT, and all the samples stained with TTC method were compared with those on the perfusion images. The pathological study with optical microscope and electron microscope were further carried on. Results The ascending slopes of γ-variate curves were different in the perfusion quantity. The normal curve of canine myocardium showed a somewhat quick ascending pattern first, and then a gradual descending pattern successively, with the ascending time of about 10-13 s, ascending CT value of about 34-37 HU, and peak CT value of about 70-81 HU. Whereas the curve on myocardial infarction demonstrated a prolonged ascending time of about 19.9 s, diminished ascending CT value of only about 20 HU, and peak CT value of about 53.8 HU, which were significantly different from the normality (P<0.05). Conclusion There are some differences in γ-variate curves between normal myocardium and myocardial infarction, which can be detected by CT perfusion scan.