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背景:磁共振成像对急性心肌梗死的研究多注重心肌灌注改变。目的:分析比较MRI征象中梗死和再灌注心肌的特征,并与病理切片染色结果进行对比。设计:完全随机分组设计,随机对照实验。单位:解放军空军总医院磁共振科,解放军总医院放射科。材料:实验于2003-10/12在解放军总医院动物实验中心完成。选用14只中国小型猪,随机分2组,每组7只,分别为梗死组和再灌注组。分别制成单纯心肌梗死和心肌梗死再灌注动物模型。术前和手术后1个月内多次进行MRI平扫、增强扫描检查。术后1个月取与MRI对应层面及厚度的心脏标本做病理大切片,进行氯化三苯基四氮唑蓝染色检查,对应氯化三苯基四氮唑蓝染色结果分别取梗死心肌(相当于左室前壁)和正常心肌(相当于左室后壁)及其相邻部标本进行苏木精-伊红染色检查观察梗死心肌范围。主要观察指标:两组猪心肌T1和T2弛豫时间改变;梗死和正常心肌的形态改变。结果:纳入中国小型猪14只,梗死组和再灌注组各7只,在造模过程中梗死组死亡1只,进入结果分析猪13只,梗死组6只,再灌注组7只。①T1,T2弛豫时间数值:梗死组梗死区心肌明显大于正常心肌犤(1159.54±78.67),(60.15±6.31)ms,(1056.15±70.95),(47.46±7.94)ms,t=2.63,5.38,P<0.05,0.01犦;再灌注组梗死区心肌也明显大于正常心肌犤(1171.14±139.98),(56.64±6.16)ms,(1074.64±97.61),(44.57±4.25)ms,t=2.64,6.24,P<0.05,0.01犦。②单纯梗死心肌与再灌注梗死心肌在MRI上均有明显强化,但两者弛豫时间和增强特征无明显差别,单纯梗死比再灌注梗死组左室扩大明显。③MRI所见与病理检查结果相对照表明病理切片氯化三苯基四氮唑蓝染色所示梗死区与MRI所见一致。结论:①MRI对心肌梗死以及左室重构评价有价值,MRI和增强扫描不能鉴别梗死和不可逆性再灌注心肌缺血区心肌组织。②再灌注对急性心肌梗死后左室重构改变有治疗作用。③MRI与病理检查具有良好的相关性。
BACKGROUND: Magnetic resonance imaging has focused on myocardial perfusion in acute myocardial infarction. OBJECTIVE: To analyze and compare the characteristics of infarcted and reperfused myocardium in MRI signs and to compare with the results of pathological staining. Design: Complete randomized block design, randomized controlled trial. Unit: PLA General Hospital, Department of Magnetic Resonance, PLA General Hospital Radiology. Materials: The experiment was performed at Animal Experimental Center of Chinese PLA General Hospital from October to October 2003. Fourteen Chinese miniature pigs were randomly divided into two groups (n = 7): infarction group and reperfusion group. Were made of simple myocardial infarction and myocardial infarction reperfusion animal model. Preoperative and postoperative 1 month multiple MRI plain scan, enhanced scan examination. One month after operation, the heart specimens from the corresponding slices and the thickness of MRI were taken for pathological examination and triphenyltetrazolium chloride blue staining was performed. Corresponding to the results of the staining with triphenyltetrazolium chloride, infarction myocardium Equivalent to the anterior wall of the left ventricle) and normal myocardium (equivalent to the posterior wall of the left ventricle) and its adjacent samples were examined by hematoxylin-eosin staining infarct size. MAIN OUTCOME MEASURES: The relaxation time of T1 and T2 of the porcine myocardium was changed; the morphological changes of infarction and normal myocardium were observed. Results: Fourteen miniature pigs were enrolled in this study. There were 7 infarcted and 7 reperfusion groups, respectively. One death occurred in the infarction group during the modeling process, and 13 pigs were included in the analysis. Six rabbits in the infarction group and seven in the reperfusion group were included in the analysis. The values of T1 and T2 relaxation time were significantly higher in infarcted area than in normal myocardium (1159.54 ± 78.67), (60.15 ± 6.31) ms, (1056.15 ± 70.95) and (47.46 ± 7.94) ms respectively, t = 2.63,5.38, P <0.05, 0.01 犦. The myocardial infarction size in reperfusion group was significantly higher than that in normal myocardium (1171.14 ± 139.98), (56.64 ± 6.16) ms, (1074.64 ± 97.61), (44.57 ± 4.25) ms, t = 2.64,6.24 , P <0.05, 0.01 犦. ② Simple myocardial infarction and myocardial infarction myocardial infarction were significantly enhanced on MRI, but the two relaxation time and enhanced features no significant difference, simple infarction compared with reperfusion infarction group left ventricular enlargement significantly. ③MRI see the results of pathological examination and control showed that pathological sections of chlorinated triphenyltetrazolium tetrazolium blue staining showed infarct area consistent with MRI. Conclusion: ①MRI is valuable in the evaluation of myocardial infarction and left ventricular remodeling. MRI and enhanced scanning can not differentiate myocardial infarction and irreversible myocardial ischemia reperfusion. ② Reperfusion has a therapeutic effect on left ventricular remodeling after acute myocardial infarction. ③ MRI and pathological examination has a good correlation.