MR扩散张量成像动态评估兔外周动脉闭塞性疾病模型后肢缺血骨骼肌形态及功能变化

MR diffusion tensor imaging for dynamic evaluation on morphological and functional changes of hind-limb ischemic skeletal muscles in rabbit models of peripheral arterial occlusive disease

目的探讨MR扩散张量成像(DWI)评估兔外周动脉闭塞性疾病(PAOD)模型后肢缺血骨骼肌形态、功能的价值。方法对32只新西兰大白兔切除右侧股动脉全长及其分支,制成PAOD模型,分别于术后第3、14、21、28天随机取8只行双后肢DTI扫描,并于扫描结束后处死动物,取后肢骨骼肌组织行病理检查。分析各时间点兔后肢术侧与健侧肌群DWI表现,对比ADC值及各项异性分数(FA)值差异,并观察病理表现。结果术后第3、14天DWI示PAOD兔术侧小腿肌群水肿、体积增大,相应ADC图显示该区域为高信号,彩色FA图上该区域为浅红色,较健侧ADC值增加、FA值减低,以第3天变化为著(P均<0.05);术后第21、28天后肢术侧及健侧肌群DWI均为等信号,ADC值及FA值差异均无统计学意义(P均>0.05)。组织病理结果显示术后第3、14天术侧后肢横纹肌肿胀、出血及坏死,以第3天为著;术后第21天个别横纹肌萎缩,并见肌束间厚壁血管增生、扩张,肌间小血管增生;术后第28天肿胀细胞基本恢复,大部分区域成纤维细胞/肌成纤维细胞增生明显,细胞间隙略增宽。结论DTI可动态观察评估兔PAOD模型后肢缺血骨骼肌随时间推移而发生的肌肉组织损伤及修复过程。

Objective To observe the value of MR diffusion tensor imaging(DTI)for dynamic evaluation on morphological and functional changes of ischemic skeletal muscle in hind limbs of rabbit models of peripheral arterial occlusive disease(PAOD).Methods PAOD models were established through excision of the full length and branches of right femoral artery with 32 New Zealand rabbits.DTI scanning of bilateral hind-limbs were conducted on the 3rd,14th,21st and 28th day after operation(each n=8),and rabbits were sacrificed after DTI,and the skeletal muscles were harvested for pathological examinations.ADC and fractional anisotropy(FA)values were measured and compared,and the pathological manifestations were observed.Results DWI showed that the operated calf muscles of PAOD rabbits were oedematous and expanded on the 3rd and 14th day after operation,the corresponding area appeared as hyper-intense on ADC maps and reddish on chromatic FA map,the operated side had higher ADC value and lower FA value than contralateral side,especially on the 3rd day after operation(all P<0.05).Bilateral muscle groups were isointense on the 21st and 28th day,and there was no significant difference of ADC nor FA values(all P>0.05).Pathological examinations showed ligated striated muscles swelling,hemorrhage and necrosis on the 3rd and 14th day after operation,especially on the 3rd day.On the 21st day after operation,atrophy of individual striated muscles,hyperplastic and angiectatic interfascicular thick-walled vessels,as well as proliferation of small intermuscular vessels were observed.On the 28th day after operation,swelling cells basically recovered,most of fibroblasts/myofibroblasts were obviously hyperplastic and intercellular space slightly widened.Conclusion DTI can dynamically and quantitatively evaluate the damage and repair process of ischemia skeletal muscle of hind limbs in PAOD rabbits over time.