不同梗死时间脑卒中大鼠腓肠肌超声弹性成像特征与其病理学特征的相关性

Correlation between ultrasonic elastography characteristics and pathological characteristics of gastronemius in MCAO rats with different infarct time

目的:探究不同梗死时间的脑卒中大鼠腓肠肌(GM)超声弹性特征表现、肌肉脂肪改变,及两者之间的关系。方法:SD雄性大鼠跟据大脑中动脉栓塞(MCAO)造模的方式和术后时间,分为假手术组(n=6)、脑梗死1.5 h组(n=7)和脑梗死2 h组(n=6)。各组大鼠在不同时间点完成体质量测量、改良神经功能缺损评估(MNSS)、背地性测试(negative geotaxis test),术后1月完成超声弹性成像评估GM硬度,取材后进行油红O测试。结果:超声结果显示,梗死2 h组偏瘫侧GM的Young′s模量均大于1.5 h组和假手术组(P<0.001),而1.5 h组与假手术组之间没有统计学差异(P=0.242);2 h组、1.5 h组和假手术组之间健侧GM的Young′s模量的差别均有统计学意义(P均<0.001)。组内比较结果显示,2 h梗死组和1.5 h梗死组大鼠左右侧GM的Young′s模量的差异均有统计学意义(2 h组,t=-12.72,P<0.001;1.5 h组,t=-3.62,P=0.01)。病理检查结果显示,三组大鼠双侧下肢GM均无明显脂肪增多。相关性结果显示,术后1月双侧GM的Young′s模量差值与背地性测试结果、MNSS评分呈正相关(背地性测试,r=0.641,P=0.003;MNSS,r=0.778,P<0.001)。结论:MCAO大鼠造模术不同梗死时间对大鼠下肢GM的超声弹性特征有影响,且MCAO术后1月大鼠肌肉间脂肪组织的改变不明显,与早期下肢GM肌肉硬度的改变可能不相关。

Objective:To observe ultrasonic elastography characteristics and intramuscular fat of gastronemius(GM)and the correlation between them in middle cerebral artery occlusion(MCAO)model rats with different infarct time.Methods:SD male rats were divided into 2 h model group(n=6),1.5 h model group(n=7),and sham-operated group(n=6).Modified neurological severity score(MNSS)and negative geotaxis test were applied to measure motor function at different time points.GM stiffness was assessed by shear wave ultrasonic elastography technology in vivo and then intramuscular fat of GM was tested by oil red O staining at the end of four weeks after modelling.Results:In the hemiplegic side,the Young′s modulus of GM of 2 h group was the largest as compared with that of the 1.5 h group and sham-group(P<0.001),while there was no significant differences between the 1.5 h group and the sham group(P=0.242).In the unaffected side,the between-group comparison of Young′s modulus of GM showed statistical difference(P<0.001).The significant within-group difference of Young′s modulus was found in 2 h group and 1.5 h group,respectively(2 h group,t=-12.72,P<0.001;1.5 h group,t=-3.62,P=0.01).Oil red O staining showed no significant increase in fat.Significant positive correlation was found between the difference of Young′s modulus and the scores of negative geotaxis test or MNSS after four weeks(negative geotaxis test,r=0.641,P=0.003;MNSS,r=0.778,P<0.001).Conclusion:The ultrasonic elastic characteristics of GM showed differences at MCAO rats with different infarct time after four weeks.However,the changes of intramuscular fat were not obvious in MCAO rats at the early stage,while it maybe be uncorrelated with the changes of GM muscle stiffness.