多层螺旋CT双期扫描对心肌梗死-再灌注损伤的评估

Dual-phase contrast-enhancement multislice computed tomography imaging in assessment of acute myocardial infarction-reperfusion injury

目的探讨多层螺旋CT(MSCT)双期扫描对急性心肌梗死动物模型的梗死心肌灌注和范围的评估价值。方法5头家猪以球囊封闭左前降支远端90 min后撤除球囊完成再灌注。30 min后行MSCT检查,静脉团注100 mL对比剂后1 min(早期扫描相)与5 min(延迟扫描相)接受2次MSCT扫描。取出心脏后切成8 mm厚短轴面切片并行氯化三苯基四氮唑(TTC)染色。MSCT延迟扫描相高增强和周边低增强区域之和及TTC不染色区域定义为梗死区域;梗死容积以各层面容积总和的百分比表示。结果MSCT上梗死心肌在早期扫描相表现为早期灌注缺损,在延迟扫描相表现为晚期增强和残余灌注缺损。早期扫描相早期灌注缺损区CT值低于正常区域[(213±55)HU vs(304±30)HU](P<0.05),延迟扫描相晚期增强区CT值高于正常区域[(360±75)HU vs(90±37)HU](P<0.01),而残余灌注缺损区低于正常区域[(152±23)HU vs(190±37)HU](P<0.05)。梗死容积百分比,MSCT测得为(8.9±1.0)%,TTC病理染色为(9.2±1.4)%,两者具有一致性。结论MSCT双期扫描在急性心肌梗死早期有不同于正常区域的特征性增强表现,对于评价心肌梗死容积与病理学方法可比性高。

Objective To explore the value of dual-phase contrast-enhancement muhislice computed tomography （MSCT） in the assessment of acute myocardial infarction volume and perfusion in porcine models. Methods The distal left anterior descending coronary arteries of 5 pigs were balloon-occluded for 90 min and followed by reperfusion. MSCT was performed 1 min （early phase） and 5 min （delayed phase） after administration bolus of 100 mL of iodinated contrast material 30 min after reperfusion. On the same day, hearts were excised, sectioned in 8 mm short-axis slices, and stained with TTC. Infarction volume was defined as the sum of the hyper-enhanced area and surrounding hypo-enhanced area in all slices on delay enhanced phase of MSCT and the TTC-negative area on TTC staining slices. Infarction volume was expressed as percentage of total slice volume. Results Acute infarction detected by MSCT was characterized by early myocardial perfusion defects in the early phase of the contrast bolus （early defects） with surrounding residual defects and late enhancement observed in the late phase. Mean CT attenuation value of early defects was significantly different from CT attenuation value of remote myocardium [ （213 ± 55）HU vs （304 ± 30）HU] （P 〈 0.05）, CT attenuation values of residual defects and late enhancement were also significantly different from those of remote myocardium [ （360 ± 75） HU vs （90 ± 37） HU and （ 152 ± 23） HU vs （ 190 ± 37） HU, repectively] （P 〈 0.01, P 〈 0.05）. The mean infarction volume was （8.9 ± 1.0） % on MSCT and （9.2 ± 1.4）% on TTC pathology images. The infarction volume assessed by MSCT compared well with TTC staining slices. Conclusion Acute reperfused myocardial infarction zone has specific enhancement pattens different to remote normal zone on dual phase MDCT, which is in good agreement with in vivo TTC pathology in the assessment of acute reperfused myocardial infarction shortly after reperfusion.