超小超顺磁性氧化铁增强磁共振对兔动脉粥样硬化斑块成分的评估

Control study of histopathology and USPIO-enhanced MR Imaging in atherosclerotic plaques of rabbits

目的:探讨超小超顺磁性氧化铁(USPIO)增强磁共振(MR)评估动脉粥样硬化(AS)斑块成分及易损性的价值。方法:将35只雄性新西兰大白兔随机分为2组,25只给予高脂饮食诱导AS,10只给予正常饮食作为对照组。所有扫描均在1.5TMR扫描仪上进行,采用Cardiac线圈。扫描序列包括:T1WISE,T2WIFSE,T2*WIGRE。所有动物于喂养10周开始扫描,完成平扫、USPIO增强24h扫描,1周后处死不同喂养阶段模型兔及同期对照组动物,每2周重复1次。USPIO使用剂量为0.05mmolFe/kg体重,MR所见与病理相对照。结果:除5只模型兔喂养中途死亡外,其余动物均完成全程扫描。所有模型兔大体标本均肉眼可见AS样改变。MR对10周模型兔病灶检出率40.0%,随病灶发展检出率明显提高。USPIO增强MR能更好识别斑块内各种成分,光镜及电镜检查示斑块内巨噬细胞可吞噬USPIO。结论:MR能动态监测AS病变并检出早期病灶;US-PIO增强MR对识别斑块成分具有独特价值,对判断斑块易损性具有较好价值。

Objective：To explore the diagnosis value of USPIO-enhanced MR imaging of atherosclerotic plaques in rabbits and characterize the composition of atherosclerotic plaques. Method：Thirty-five male New Zealand white rabbits were randomly divided to two groups： 25 rabbits were induced by atherogenic diet to set up the model and 10 rabbits with the normal diet were served as the control group. All MRI was performed on a high-resolution 1. 5T MR scanner with the cardiac coil. Routine sequences included Tl-weighted spin-echo, T2-weighted fast spinecho, T2 ＊ -weighted gradient-echo. All the rabbits were imaged prior to and 24 hours after administration of USPIO after raising 10 weeks. After a week delay ,the rabbits were killed in different raising periods. And this was repeated every 2 weeks. USPIO was injected intravenously at a dose of 0.05 mmolFe/kg body weight. MR findings were correlated with histopathologic findings. Result：All the rabbits were finished the whole study except for 5 model rabbits who were died a natural death. Rabbits induced by atherogenic diet were all developed atherosclerotic lesion on gross. The detection rate of early lesions of AS on MR was 40.0% ,and rate was raising in the progress of lesions. USPIO-enhanced MR characterize the composition of atherosclerotic plaques well. The analysis of electron microscopical and light microscope proved that the iron particles were in the macrophages in the plaque. Conclusion：MR imaging can dynamic monitor the progress of AS,and the early lesions can be detected. USPIO-enhanced MR imaging can help to depicting the vulnerable of atherosclerotic plaque ,and characterizing the composition of atherosclerotic plaques.