多层螺旋CT区分兔存活与梗死心肌

MSCT definition of viable and infarcted myocardium in rabbits

目的评价多层螺旋CT(MSCT)动态成像能否区分兔存活与梗死心肌。方法健康新西兰大白兔50只,随机分为对照组(10只)、冠状动脉前降支悬吊组(20只)与结扎组(20只),均在施加作用因素1h后行MSCT动态增强检查,注射对比剂开始后3s至150s连续扫描,并行10min延迟扫描,测定缺血区心肌强化峰值与达峰时间、延迟强化CT值。处死动物后行TTC染色、组织学、心肌肌动蛋白抑制因子免疫组化染色,观察缺血区心肌是否存活。结果冠状动脉悬吊组TTC染色阴性,组织学可见心肌细胞轻度肿胀及炎细胞浸润、微血管改变轻微,免疫组化评分为(158.20±9.40);动态扫描缺血区CT峰值(210.90±16.80)HU,达峰时间为(51.00±1.80)s,延迟增强CT值为(58.00±13.90)HU。冠状动脉结扎组TTC染色阳性,组织学可见心肌细胞明显肿胀、结构消失,微血管异常明显,免疫组化评分为(60.00±18.30);动态扫描缺血区CT峰值(157.60±23.60)HU,达峰时间为(65.00±3.10)s,延迟强化CT值为(89.00±15.30)HU。两组免疫组化评分、缺血区心肌CT峰值及达峰时间、延迟强化差异均有显著统计学意义(P<0.05)。对照组CT峰值、达峰时间及延迟扫描CT值与结扎及悬吊组差异有统计学意义(P<0.05)。结论16层螺旋CT动态扫描可作为区分兔梗死与存活心肌的影像学检查方法。

Objective To observe if dynamic imaging of muhislice CT （MSCT） can differentiate viable from infarcted my ocardium in rabbits. Methods Fifty heathly New Zealand rabbits were randomly divided into left anterior decending artery （LAD） hung group （n= 20）, LAD ligated group （n=20） and control group （n= 10）. MSCT perfusion scan was performed 1 h after operation. The examination schedule included dynamic scan from 3 s to 150 s after contrast medium injection and delayed scan 10 min later. The peak enhancement, time to peak value, and delayed enhancement of ischemic myocardium were measured. The viability of ischemic myocardium was defined through observing TTC staining, histology, and histo- chemistry stain of cardiac troponin inhibitor （CTnI）. Results In LAD hung group, TTC stain was negative. On pathologic examination, slight swelling of myocardium cells, inflammation cells and mild abnormality of microvessel were detected. The grade of histochemistry stain of LAD hung group was （158.20±9.40）, while the peak enhancement, time to peak val- ue and delay enhancement was （210.90±16.80）HU, （51.00±1. 80）s, and （58.00±13.90）HU, reseparately. In LADli- gated group, TTC stain was positive. On pathologic examination, obvious swelling and necrosis of myocardium cells, prominent abnormality of microvessel were found. The grade of histochemistry stain of LAD ligated group was （60.00± 18.30）, whereas the peak enhancement, time to peak value and delay enhancement was （157.60±23.60）HU, （65.00± 3.10）s and （89.00±15.30） HU, respectively. There were obvious differences of the grade of histochemistry stain, the peak enhancement, time to peak value and delay enhancement between LAD hung and ligated groups （P〈0.05）. The differences of the peak enhancement, time to peak value and delay enhancement between control group and LAD hung group, and between control group and LAD ligated group were significant （P〈0.05）. Conclusion Dynamic scan with 16 slice spiral CT can differentiate infracted myocardium in rabbit from viable myocardium.