定量磁敏感图动态评估兔肾缺血再灌注损伤的可行性研究

Feasibility Study of Quantitative Susceptibility Mapping in the Dynamic Evaluation of Renal Ischemia-Reperfusion Injury in Rabbits

目的探讨定量磁敏感图(QSM)能否反映兔肾缺血再灌注损伤(IRI)的动态过程。方法健康新西兰大白兔36只,随机分为IRI组(30只)和假手术组(6只)。IRI组及假手术组分别于建模前(IRI-pre)、建模后1 h、12 h、24 h、48 h(IRI-1h、IRI-12h、IRI-24h、IRI-48h)行左肾T_(2)WI和QSM扫描,IRI组在各个时间点MRI扫描结束后随机选取6只处死,假手术组在IRI-48h时MRI扫描结束后处死。按照左肾外髓轮廓手工勾画感兴趣区,记录外髓磁化率值。所有左肾标本行HE染色,计算病理损伤评分。采用重复测量方差分析比较不同时间点假手术组和IRI组兔肾外髓磁化率值的差异。采用非参数Kruskal-Wallis检验评估各时间点病理损伤评分的差异。采用Spearman相关性分析比较IRI组建模后外髓磁化率值与病理损伤评分的相关性。结果IRI组在IRI-pre、IRI-1h、IRI-12h、IRI-24h和IRI-48h时的外髓磁化率值分别为(43.23±3.06)×10^(-3) ppm、(﹣5.78±1.82)×10^(-3) ppm、(6.87±3.85)×10^(-3) ppm、(10.56±2.28)×10^(-3) ppm、(19.93±2.18)×10^(-3) ppm。IRI组各时间点磁化率值差异有统计学意义(P<0.05)。假手术组各时间点磁化率值差异无统计学意义(P>0.05)。IRI组外髓磁化率值与细胞水肿评分呈负相关(ρ=-0.70,P<0.05),与细胞坏死、间质炎症、管型和病理损伤总分呈正相关(ρ=0.71、0.60、0.76、0.53,P<0.05)。结论定量磁敏感图能反映兔肾早期IRI后外髓的动态变化,是一种无创评估肾IRI的影像手段。

Objective To explore whether quantitative susceptibility mapping(QSM)can assess the dynamic process of renal ischemia reperfusion injury(IRI)in rabbits.Methods 36 healthy New Zealand rabbits were randomly assigned to the IRI group(n=30)and the sham group(n=6).All rabbits underwent MRI examination including T2 WI sequence and QSM sequence before the operation(IRI pre),and 1 h,12 h,24 h,48 h after the operation(IRI-1 h,IRI-12 h,IRI-24 h,IRI-48 h,respectively).Six rabbits in the IRI group were sacrificed at each time point after MRI examination.All rabbits in the sham group were sacrificed at the IRI-48 h time point.Regions of interest(ROIs)were manually delineated in the outer medulla,and then the magnetic susceptibility values were recorded.All specimens of left kidneys were stained with hematoxylin-eosin(HE).The pathological scores of renal injury were calculated.The repeated measurement analysis of variance was used to compare the differences in the magnetic susceptibility values among the different time points in the IRI group and the sham group.Differences in the pathological score of renal injury were analyzed by the nonparametric Kruskal-Wallis test.Spearman correlation analysis was used to compare the correlation between the magnetic susceptibility values of the outer medulla and the pathological score of renal injury in the IRI group.Results In the IRI group,the magnetic susceptibility values of the outer medulla at IRI-pre、IRI-1 h、IRI-12 h、IRI-24 h,and IRI-48 h time points were(43.23±3.06)×10^(-3) ppm、(﹣5.78±1.82)×10^(-3) ppm、(6.87±3.85)×10^(-3) ppm、(10.56±2.28)×10^(-3) ppm、(19.93±2.18)×10^(-3) ppm,respectively.In the IRI group,the magnetic susceptibility values of the outer medulla had significant differences among the different time points(P<0.05).In the sham group,there were no significant differences in the magnetic susceptibility values of the outer medulla among the different time points(P>0.05).The magnetic susceptibility values of the outer medulla had negative correlation with the scores of cell edema in the IRI group(ρ=-0.70,P<0.05).The magnetic susceptibility values of the outer medulla had positive correlation with the scores of necrocytosis,interstitial inflammation,cast and the total pathological score of renal injury(ρ=0.71,0.60,0.76,0.53,P<0.05,respectively).Conclusion QSM can assess the dynamic changes of the outer medulla in the early stage of renal IRI of rabbits,which can be used as a noninvasive method to evaluate the early stage of renal IRI.