多带宽DTI-IVIM技术评估肾移植术后早期移植肾功能受损的价值

The value of multiband DTI-IVIM in evaluating renal allograft dysfunction early after renal transplantation

目的 探讨多带宽扩散张量成像-体素内不相干运动(multiband DTI-IVIM)技术评估肾移植术后早期不同程度受损移植肾功能的价值。方法 前瞻性收集异体肾移植术后2~4周病人92例行常规MRI、multiband DTIIVIM MRI检查。根据估算肾小球滤过率(eGFR)将病人分为3组:组1,eGFR≥60 mL/(min·1.73 m^2)(45例);组2,30 mL/(min·1.73 m^2)≤eGFR<60 mL/(min·1.73 m^2)(27例);组3,e GFR<30 mL/(min·1.73 m^2)(20例)。测量移植肾皮髓质的表观扩散系数(ADC)、单纯扩散系数(ADCslow)、微循环灌注系数(ADCfast)、灌注分数(f)、各向异性分数(FA)。采用配对t检验分析比较皮髓质间各参数值差异;采用单因素方差分析比较组间各参数值的差异;采用Pearson相关分析研究移植肾各参数值与eGFR间的相关性以及皮髓质FA值与其他各参数值的相关性。结果 组1肾皮质FA值低于髓质,余参数值高于髓质(P<0.05),组2、组3的ADCslow、ADCfast值及组2的f值皮髓质间差异无统计学意义(P>0.05)。组2肾皮髓质ADC、ADCslow、皮质f值及髓质FA值均低于组1(P<0.05)。组3肾皮髓质ADC、髓质ADCslow及髓质FA值均低于组2(P<0.05)。组3肾皮髓质ADC、ADCslow、f值、皮质ADCfast值及髓质FA值均低于组1(P<0.05)。各参数中,髓质FA值对组1和组2、组2和组3、组1和组3鉴别诊断效能最高(AUC分别为0.855、0.831、0.983);联合DTI-IVIM参数鉴别各组的能力最高(AUC分别为0.954、0.885、1.000)。除髓质ADCfast值、f值及皮质FA值外,移植肾各参数值与eGFR均呈中度正相关(r值为0.333~0.707,P<0.05)。髓质FA值与皮髓质ADC值、皮髓质ADCslow值及髓质f值均呈中度正相关(r值为0.335~0.526,P<0.05)。结论 multiband DTI-IVIM联合DTI和IVIM技术,可以评估并鉴别移植术后早期不同功能状态的移植肾功能。

Objective To explore the value of multiband diffusion tensor imaging-intravoxel incoherent motion(multiband DTI-IVIM)technique in evaluating renal allograft dysfunction early after renal transplantation.Methods A total of 92 renal allograft recipients were prospectively collected for routine and multiband DTI-IVIM MR imaging 2-4 weeks after transplantation.92 recipients were divided into three groups according to the estimated glomerular filtration rate(eGFR):group 1,eGFR≥60 mL/(min·1.73 m^2)(n=45);group 2,eGFR<60 mL/(min·1.73m^2)(n=27);and group 3,eGFR<30 mL/(min·1.73 m^2)(n=20).The apparent diffusion coefficient(ADC),true diffusion coefficient(ADCslow),pseudo-diffusion coefficient(ADCfast),perfusion fraction(f),and fractional anisotropy(FA)values were measured.The paired t-test was used to compare the differences of parameters between the cortex and medulla of renal allografts.One-way analysis of variance was used to compare the differences of parameters among three groups.Pearson correlation was used to evaluatethe correlation between parameters of transplanted kidney and eGFR,and the correlation between FA values and other parameters.Results The FA value of renal cortex in group 1 was significantly lower than that of medulla,and the other values of renal cortex were significantly higher than those of medulla(P<0.05).The ADCslow and ADCfast values did not significantly differ between cortex and medulla in the groups 2 and 3,and neither did the f value in the group 2(P>0.05).The cortical and medullar ADC and ADCslow values of,cortical f value,and medullar FA value were significantly lower in the group 2 than in the group 1(P<0.05).The cortical and medullar ADC value,medullar ADCslow value and medullar FA value were significantly lower in the group 3 than in the group 2(P<0.05).The cortical and medullar ADC,ADCslow and f values,cortical ADCfast value and medullar FA value were significantly lower in the group 3 than in the group 1(P<0.05).Among the parameters,the medullar FA value was the most effective in differentiating between groups 1 and 2,2 and 3,1 and 3(the area under curve was 0.855,0.831,and 0.983,respectively),and the combining DTI and IVIM measurements achieved the highest the areas under curve(0.954,0.885 and 1.000,respectively).With exceptions of medullar ADCfast,f,and cortical FA value,all parameters of allograft significantly positively correlated with eGFR(r value was 0.333~0.707,P<0.05).The cortical and medullar ADC and ADCslow values,and medullarf value moderately positively correlated with medullar FA value(r value was 0.335~0.526,P<0.05).Conclusion Combined DTI and IVIM can be used to evaluate and differentiate renal allograft function in different functional states early after renal transplantation.