定量磁敏感图量化评价早期糖尿病肾病肾功能损伤的价值

Quantitative evaluation of renal injury in the early diabetic nephropathy with quantitative susceptibility mapping

目的探讨定量磁敏感图(QSM)在早期糖尿病肾病(DN)患者肾功能损伤评估中的价值。方法前瞻性收集2019年10月至2020年12月间苏州大学附属第三医院早期DN患者32例,根据估算肾小球滤过率(eGFR)水平分3组:DN1(eGFR≥90 ml·min^(-1)·1.73 m^(-2),11例)、DN2(60~<90 ml·min^(-1)·1.73 m^(-2),11例)、DN3(30~<60 ml·min^(-1)·1.73 m^(-2),10例)。同期招募32名正常志愿者作为对照组。对双肾进行QSM扫描,测量肾皮质、髓质的磁化率。采用配对样本t检验比较左、右肾脏间及皮质、髓质间磁化率的差异。采用单因素方差分析比较各组间肾皮质、髓质磁化率的差异,两两比较采用最小显著差值法(LSD)。采用Pearson相关分析髓质磁化率与eGFR的相关性。应用ROC曲线分析QSM参数对DN和不同DN严重程度的诊断效能。结果正常志愿者和DN患者的双肾髓质磁化率低于肾皮质,差异均有统计学意义(P均<0.001);左肾、右肾皮质间磁化率差异均无统计学意义(P均>0.05);左肾、右肾间髓质磁化率差异有统计学意义(P均<0.05)。对照组与DN1~DN3组间双侧肾皮质磁化率的总体差异无统计学意义(P均>0.05)。对照组、DN1、DN2和DN3组的左肾肾髓质磁化率分别为(-4.46±1.16)×10^(-2)、(-5.96±0.97)×10^(-2)、(-7.97±1.25)×10^(-2)、(-9.58±1.45)×10^(-2)ppm,右肾分别为(-3.70±0.65)×10^(-2)、(-5.06±1.28)×10^(-2)、(-7.33±1.46)×10^(-2)、(-9.09±2.22)×10^(-2)ppm。双侧肾髓质磁化率的总体差异有统计学意义(P均<0.05),且两两组间比较差异均有统计学意义(P均<0.05)。肾髓质磁化率与eGFR呈线性正相关(左肾r=0.732,P<0.001;右肾r=0.684,P<0.001)。左、右肾髓质磁化率诊断正常与DN的ROC曲线下面积(AUC)分别为0.931、0.943;诊断DN1与DN(2和3)的AUC分别为0.952、0.883;诊断DN(1和2)与DN3的AUC分别为0.888、0.831。结论QSM定量参数磁化率对早期DN的诊断和分期有一定价值,其中肾髓质磁化率有较高的诊断效能。

Objective To explore the value of quantitative susceptibility mapping(QSM)in evaluating renal injury in patients with early diabetic nephropathy(DN).Methods From October 2019 to December 2020,32 patients with early DN were prospectively enrolled in the Third Affiliated Hospital of Soochow University.According to the estimated glomerular filtration rate(eGFR),they were divided into three groups:DN1(eGFR≥90 ml·min^(-1)·1.73 m^(-2),11 cases),DN2(60-<90 ml·min^(-1)·1.73 m^(-2),11 cases)and DN3(30-<60 ml·min^(-1)·1.73 m^(-2),10 cases).At the same time,32 normal volunteers were recruited as the control group.Both kidneys were scanned by QSM to measure the susceptibility of renal cortex and medulla.Paired samples t-test was used to compare the differences of the susceptibility between left and right kidneys and between cortex and medulla.One-way analysis of variance was performed to compare the differences of corresponding susceptibility values among different groups,and LSD-t was used for the pairwise comparison.Pearson correlation test was performed between the susceptibility value of the medulla and eGFR.The ROC curve was used to analyze the diagnostic efficacy of QSM parameters in the diagnosis of DN and different degrees of severity of DN.Results The susceptibility values of bilateral renal medulla in normal volunteers and patients with DN were lower than those of renal cortex(all P<0.001).There was no significant difference in the susceptibility value between left and right renal cortex(all P>0.05).There was significant difference in the susceptibility value between left and right medulla(all P<0.05).There was no significant difference in the susceptibility value of bilateral renal cortex among the control group and the DN1-DN3 groups(both P>0.05).The susceptibility values of left renal medulla in control group,DN1,DN2 and DN3 groups were(-4.46±1.16)×10^(-2),(-5.96±0.97)×10^(-2),(-7.97±1.25)×10^(-2),(-9.58±1.45)×10^(-2)ppm,of right renal medulla were(-3.70±0.65)×10^(-2),(-5.06±1.28)×10^(-2),(-7.33±1.46)×10^(-2),(-9.09±2.22)×10^(-2)ppm,respectively.The overall difference of the susceptibility value of bilateral renal medulla was statistically significant(both P<0.05),and there were significant differences between each two groups(all P<0.05).The linear positive correlation were found between the susceptibility values of renal medulla and the corresponding eGFR(left kidney r=0.732,P<0.001;right kidney r=0.684,P<0.001).The areas under the ROC curve(AUC)of left and right renal medulla susceptibility value in diagnosis of normal and DN were 0.931 and 0.943,of DN1 and DN(2 and 3)were 0.952 and 0.883,of DN(1 and 2)and DN3 were 0.888 and 0.831,respectively.Conclusion The susceptibility value of QSM quantitative parameter has a certain value in the staging and differential diagnosis of early DN,among which the susceptibility value of renal medulla has higher diagnostic efficiency.