磁共振扩散峰度成像对肝移植术后急性排斥反应的诊断价值

Diagnostic value of MR diffusion kurtosis imaging in acute cellular rejection after liver transplantation

目的探讨磁共振扩散峰度成像(DKI)对于原位肝移植术后患者发生急性排斥反应(ACR)的诊断价值。方法回顾性连续收集2014年10月~2018年4月肝移植术后随访在我院进行磁共振检查的病人112例,其中13例未见明确病变、9例肿瘤复发、3例图像质量不佳被剔除,18例经穿刺病理诊断为ACR,另外69例对照组包括56例胆道并发症、11例血管并发症以及2例药物性肝损伤。所有患者均行DKI扫描,b值为0、200、500、1000、1500、2000 s/mm2,两名放射科医生分别独立测量D值、K值和ADC值。组间相关系数(ICC)用于评价组间一致性,t检验或Mann-Whitney U检验以及ROC曲线用于比较两组间的差异及评价各个参数的诊断效能。结果两名测量者间一致性良好(ICC=0.843-0.878)。D值和K值在两组间均有统计学差异,P值分别为0.012和0.003,ADC值在两组间没有统计学差异。ROC曲线分析显示,K值对于ACR的诊断效能最大,AUC、敏感度、特异度和准确度分别为0.925、0.947、0.789、0.737。结论磁共振扩散峰度成像对于肝移植术后急性排斥的诊断价值优于传统单指数模型扩散加权成像。

Objective To investigate the diagnostic value of diffusion kurtosis imaging(DKI)in acute cellular rejection(ACR)after orthotopic liver transplantation(OLT).Methods During October 2014 to April 2018,112 patients underwent MR examination with DKI sequence following OLT(postoperative days:7-378).A total of 18 patients were diagnosed with ACR(reference standard:biopsy).The remaining 91 patients were as follows:56 with biliary complications(reference standard:ERC or PTC),11 with vascular complications(reference standard:surgery or DSA),2 with drug induced liver injury(DILI),13 normal(excluded),3 insufficient image quality(excluded),and 9 tumor recurrence(excluded).Finally,87 patients were included in this study.They were divided into the ACR group and non-ACR group.For each patient,DKI was performed with a 3.0 T MRI system with b values of 0,200,500,1000,1500 and 2000 sec/mm2.Corrected diffusion(D),kurtosis(K),and apparent diffusion coefficient(ADC)values were measured by two radiologists independently.Interobserver repeatability was assessed by using the interclass correlation coefficient(ICC).Student’s t-test or Mann-Whitney U-test,and receiver operating characteristic(ROC)curves were used for statistical analysis.Results Interobserver agreements between the two observers were excellent(ICC=0.843-0.878).D values were significantly lower in the ACR group than those in the control group(P=0.012).K values in the ACR group were significantly higher compared to those in the control group(P=0.003).No significance was found in ADC values between the ACR and non-ACR group(P=0.560).Regarding the comparison of the diagnostic performance,K values showed the highest AUC value of 0.925,and the corresponding values for sensitivity,specificity and accuracy were 0.947,0.789,and 0.737,respectively.Conclusion DKI metrics show a promising potential in diagnosing ACR after OLT compared to monoexponential diffusion method.