体素内不相干运动成像评估鼠肾冷缺血再灌注损伤

The Evaluation of Kidney Cold Ischemia Reperfusion Injury using Intravoxel Incoherent Motion Magnetic Resonance Imaging in A Rat Model

目的探讨体素内不相干运动(IVIM)技术评价大鼠肾脏冷缺血再灌注损伤(CIRI)的可行性和应用价值。方法采用随机数表法将大鼠分为四组,每组25只,分为假手术组(A0组)、冷缺血1 h组(A1组)、冷缺血2 h组(A2组)和冷缺血4 h组(A3组)。分别在术前、术后1 h、1天、2天、5天行IVIM扫描。采集数据后进行图像后处理,测量大鼠肾脏皮髓质的表观扩散系数(ADC)、真实扩散系数(D)、循环灌注相关系数(D^(*))和灌注分数(PF)。使用组内相关系数(ICC)检验一致性和可重复性。取血进行生化检查,并取左肾病理切片做肾组织HE染色观察形态学特点及肾周毛细血管(PTC)密度检测。使用重复测量方差分析比较不同分组MRI参数值及生化、PTC值的差异。应用Spearman相关分析评价MRI参数值与生化指标、PTC值的相关性。结果术后1 h各组大鼠左肾皮髓质的ADC、D、D^(*)和PF值均减低(P<0.05)。冷缺血组的IVIM各参数值均低于假手术组,且随着冷缺血时间延长,IVIM各参数值呈逐渐下降。A0组和A1组的IVIM各参数值、A2组的ADC和D值均于术后5天内恢复到术前基线水平(P>0.05)。A2组的D^(*)和PF值以及A3组的IVIM各参数值在术后5天仍低于术前基线水平(P<0.05)。肾皮质和肾髓质ADC、D、D^(*)、PF值与PTC密度呈高度正相关(P均<0.001)。肾皮质和肾髓质D^(*)、PF值与血清肌酐(Scr)、尿素氮(BUN)值呈负相关(P均<0.05)。肾皮质和肾髓质D值与BUN值无相关性(P均>0.05)。结论IVIM能够无创定量评估肾脏不同程度CIRI的变化情况。

Objective To investigate the feasibility and value of intravoxel incoherent motion(IVIM)in evaluating cold ischemia-reperfusion injury(CIRI)in rat model.Methods The rats were randomly divided into 4 groups with 25 rats in each group.The rats were divided into sham operation group(Group A0),cold ischemia for 1 hour group(Group A1),cold ischemia for 2 hours group(Group A2)and cold ischemia for 4 hours group(Group A3).IVIM MRI scan were performed before operation,1 hour,1 day,2 days and 5 days after operation.The post-processed images were performed to measure the apparent diffusion coefficient(ADC),true diffusion coefficient(D),circulating perfusion correlation coefficient(D^(*))and perfusion fraction(PF)of rat renal cortex and medulla.The intra group correlation coefficient(ICC)was used to test the consistency and repeatability.Biochemical tests of serum creatinine(Scr)and blood urea nitrogen(BUN)were detected.Pathological sections of left kidney were taken for HE staining and peritubular capillary(PTC)density detection.Repeated measures ANOVA was used to compare the differences of MRI parameters,biochemical and PTC values in different groups.Spearman correlation analysis was used to evaluate the correlation between MRI parameters and biochemical and PTC values.Results The ADC,D,D^(*)and PF values of left renal cortex and medulla in each group at 1 hour after operation were lower than those before operation(P<0.05).The IVIM parameters of cold ischemia group were lower than those of sham operation group,and the IVIM parameters decreased gradually with the extension of cold ischemia time.The values of IVIM parameters in Group A0 and A1,ADC and D values in Group A2 were all recovered to the preoperative baseline level within 5 days after operation(P>0.05).The D^(*)and PF values of Group A2 and the IVIM parameters of Group A3 were still lower than the preoperative baseline level within 5 days after operation(P<0.05).ADC,D,D^(*),PF values of renal cortex and medulla were highly positively correlated with PTC density(P<0.001).D^(*)and PF values of renal cortex and medulla were negatively correlated with Scr and BUN(P<0.05).There was no correlation between D and BUN values(P>0.05).Conclusion IVIM MRI can evaluate the changes of CIRI with different degrees quantitatively and noninvasively.