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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。
Objective To investigate the differential diagnosis value of diffusion tensor imaging (DTI) and blood oxygenation-dependent imaging (BOLD) in acute renal transplant rejection (AR) and acute tubular necrosis (ATN) in order to explore noninvasive and sensitive evaluation of renal graft function Methods. Methods Totally 51 patients who underwent 2 ~ 3 weeks after allogeneic kidney transplantation in the First Central Hospital of Tianjin from May 2012 to March 2014 were enrolled in this study. All of the subjects were enrolled in the Siemens MAGNETOM Trio Tim 3.0T superconductor Magnetic resonance imaging (MRI) and fat suppressed planar echo oblique coronal DTI (diffusion-sensitive gradient applied in 6 non-linear directions with a b value of 0.300 s / mm2) and oblique coronal plane BOLD check. Patients were divided into three groups: normal renal transplantation group, AR group and ATN group, of which AR group and ATN group were confirmed by pathological puncture. The apparent diffusion coefficient (ADC) value, anisotropic fraction (FA) value and apparent spin-spin relaxation rate (R2 *) values of renal cortex and medulla were measured and calculated in each group. Variance analysis was performed to compare the differences in parameters between groups. The receiver operating characteristic curve (ROC) was used to compare the diagnostic value of the corticomedullary ADC value and the R2 * value to the AR group and the ATN group, and to determine the best diagnostic threshold. Results Compared with the normal group, the cortical ADC value, medulla ADC value and R2 * value in AR group were significantly decreased [ADC value of cortex (× 10-3mm2 / s): 2.31 ± 0.49 vs 2.85 ± 0.28, 10-3mm2 / s): 2.21 ± 0.50 vs 3.07 ± 0.38, R2 * value (1 / s): 19.5 ± 3.3 vs. 22.7 ± 3.3, all P <0.05〕. Compared with ATN, the cortical ADC value, medulla ADC value and R2 * value in AR group were significantly decreased [cortical ADC value (× 10-3mm2 / s): 2.31 ± 0.49 vs 2.85 ± 0.27, medulla ADC value (× 10- 3mm2 / s): 2.21 ± 0.50 vs 2.76 ± 0.35, R2 * value (1 / s): 19.5 ± 3.3 vs 23.6 ± 2.8, all P <0.05〕. The FA values and cortical R2 * There was no significant difference (P> 0.05). The optimal diagnostic thresholds of cortical ADC value, medullary ADC value and medullary R2 * value were 2.68 × 10-3mm2 / s, 2.73 × 10-3mm2 / s and 21.4 / s respectively, which were sensitive Sex and specificity were above 70%, the differential diagnosis of efficacy no significant difference (P> 0.05). Conclusion DTI and BOLD are noninvasive and effective in differentiating AR and ATN in renal allografts. ADC value of medulla and medullary R2 * values can be used as differential diagnosis indicators.