Abstract:

Objective To investigate the value of diffusion-tensor imaging（DTI）and blood oxygenlevel-dependent（BOLD）in differentiation acute rejection（AR）and acute tubular necrosis（ATN），and to explorea sensitive，noninvasive strategy of evaluating renal allograft function. Methods A total of 51 renal allograftrecipients at 2-3 weeks after transplantation in Tianjin First Center Hospital were included in this study from May 2012 to March 2014 and they were examined using a fat-saturated echo-planar DTI and GRE-BOLD sequence in oblique- coronal orientation at 3.0 Tesla magnetic resonance（MR）imager（diffusion directions ＝ 6，b ＝ 0.300 s/mm2）.All patients were divided into three groups: normal renal function group，acute rejection group and acute tubularnecrosis group，and the AR and ATN groups were confirmed by pathological biopsy. Mean apparent diffusioncoefficient（ADC）and mean fractional anisotropy（FA）and apparent spin-spin relaxation rate（R2*）values of thecortex and medulla were determined separately and comparisons of parameters between the 3 groups were tested byone-way ANOVA analysis. Meanwhile，the receiver operating characteristic（ROC）curves was used to compare the differential diagnostic efficacies of every parameters in AR group and ATN group for determine the best diagnosticthreshold. Results Compared with normal group，mean ADC value in cortex，mean ADC value in medulla and medullary R2* value of AR group were significantly lower〔mean ADC value in cortex（×10-3mm2/s）：2.31±0.49 vs.2.85±0.28，mean ADC value in medullar（×10-3mm2/s）：2.21±0.50 vs. 3.07±0.38，medullary R2* value（1/s）：19.5±3.3 vs. 22.7±3.3，all P ＜ 0.05〕. Compared with ATN group，mean ADC value in cortex，mean ADC value in medulla and medullary R2* value of AR group were significantly lower〔mean ADC value in cortex（×10-3mm2/s）： 2.31±0.49 vs. 2.85±0.27，mean ADC value in medullar（×10-3mm2/s）：2.21±0.50 vs. 2.76±0.35，medullary

R2*value（1/s）：19.5±3.3 vs. 23.6±2.8，all P ＜ 0.05〕. There were no significant differences of mean cortical R2* value，mean FA value in the cortex and medulla among the three groups（P ＞ 0.05）. ROC curves revealed that the cut-off values of cortical ADC，medullary ADC and medullary R2* in differentiation AR and ATN were2.68×10-3 mm2/s，2.73×10-3 mm2/s and 21.4/s respectively. Both sensitivity and specificity were higher than 70%. The three parameters had comparable power in differentiating ATN and AR allografts（P＞0.05）. Conclusion DTI and BOLD can identify transplanted renal AR and ATN noninvasively，and mean R2* value in the medulla，mean ADC value in the cortex and medulla can be used as index for differentiating.

摘要：

目的 探讨扩散张量成像（DTI）、血氧水平依赖成像（BOLD）对移植肾急性排异反应（AR）和急性肾小管坏死（ATN）鉴别诊断价值，以期探寻无创、敏感的评价移植肾功能的方法。方法 选取2012 年 5 月— 2014 年 3 月在天津市第一中心医院进行异体肾移植术后 2 ～ 3 周的患者 51 例纳入本研究，所有受试者均于Siemens MAGNETOM Trio Tim 3.0T 超导磁共振扫描仪进行常规磁共振成像（MR）及脂肪抑制平面回波斜冠状面 DTI 检查（在 6 个非共线性方向上施加扩散敏感梯度场，b 值为 0.300 s/mm2）及斜冠状面 BOLD 检查。患者分为三组 ：移植肾功能正常组、AR 组及 ATN 组，其中 AR 组与 ATN 组均经病理穿刺证实。分别测量并计算各组移植肾皮质、髓质的表观扩散系数（ADC）值、各向异性分数（FA）值及表观自旋 - 自旋弛豫率（R2*）值，采用单因素方差分析比较移植肾各组间各参数值的差异。采用受试者工作特征曲线（ROC）比较皮髓质 ADC 值及 R2* 值对 AR 组以及 ATN 组的鉴别诊断效能并确定最佳诊断阈值。结果 与正常组相比，AR 组皮质 ADC 值、髓质 ADC 值、R2* 值显著下降〔皮质 ADC 值（×10-3mm2/s）：2.31±0.49 比 2.85±0.28，髓质 ADC 值（×10-3mm2/s）：2.21±0.50 比 3.07±0.38，R2* 值（1/s）：19.5±3.3 比 22.7±3.3，均 P ＜ 0.05〕。与 ATN 相比，AR 组皮质 ADC 值、髓质 ADC 值、R2* 值显著下降〔皮质ADC 值（×10-3mm2/s）：2.31±0.49 比 2.85±0.27， 髓 质 ADC 值（×10-3mm2/s）：2.21±0.50 比 2.76±0.35，R2* 值（1/s）：19.5±3.3 比 23.6±2.8，均 P ＜ 0.05〕；三组之间皮质、髓质 FA 值及皮质 R2* 值均无明显差 异（P ＞ 0.05）。皮质 ADC 值、髓质 ADC 值及髓质 R2* 值对 AR 组与 ATN 组鉴别的最佳诊断阈值分别为2.68×10-3mm2/s、2.73×10-3mm2/s、21.4/s，其敏感性和特异性均在 70% 以上，鉴别诊断效能均无明显统计学差异（P ＞ 0.05）。结论 DTI、BOLD 能无创、有效鉴别移植肾 AR 与 ATN，其中皮髓质 ADC 值及髓质 R2* 值可作为鉴别诊断指标。