MR IVIM-DWI 及 DCE-MRI 对直肠癌系膜淋巴结良恶性的诊断价值

目的：探讨 MR 体素内不相干运动扩散加权成像(IVIM-DWI)及动态增强磁共振成像(DCE-MRI)在鉴别直肠癌直肠系膜淋巴结转移的应用价值。方法38例经病理确诊为直肠癌的患者，术前行 IVIM-DWI 及 DCE-MRI 检查。比较转移性淋巴结(n=28)与非转移性淋巴结(n=27)的短径、短径-长径比、IVIM-DWI 参数值表观扩散系数(ADC)、单纯扩散系数(D)、伪扩散系数(D?)和灌注分数(f)]及 DCE-MRI 半定量参数值曲线上升斜率(Slope)、最大上升斜率(Maxslope)、对比增强比(CER)、对比剂清除率(Washout)、达峰时间(TTP)、前90 s 增强曲线下面积(iAUC90)和前180 s 增强曲线下面积(iAUC180)]。结果转移性与非转移性淋巴结在平均短径(8.87 mm±2.829 mm vs 6.83 mm±1.075 mm)、D 值(0.824±0.113)×10-3 mm2/s vs (1.033±0.244)×10-3 mm2/s)]、CER(1.588±0.664 vs 1.054±0.419)、iAUC90(22.89±9.83 vs 13.59±5.34)和 iAUC180(49.38±20.19 vs 30.31±11.67)上差异有统计学意义(P ≤0.001)；在短径-长径比、ADC 值、D?值、f 值及 Slope、Maxslope、Washout、TTP 上无统计学差异(P >0.05)。鉴别转移性及非转移性淋巴结的最佳阈值(各自的曲线下面积、敏感性、特异性)分别为：短径=7.1 mm(0.744、64.2%、85.1%)、D=0.906×10-3 mm2/s (0.821、81.5%、75.0%)、CER=1.05(0.749、85.7%、62.9%)、iAUC90=13.42(0.780、85.7%、62.9%)及 iAUC180=49.65(0.770、50.0%、100%)。结论IVIM-DWI 及 DCE-MRI 在鉴别直肠癌直肠系膜转移性及非转移性淋巴结的诊断中具有一定的意义。

Value of IVIM-DWI and DCE-MRI in the assessment of benign and malignant mesorectal lymph nodes in rectal cancer

Objective To investigate the diagnostic value of intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)in differentiating non-metastatic from metastatic mesorectal lymph nodes in rectal cancer.Methods IVIM-DWI and DCE-MRI were performed preoperatively in 38 patients with histologically proven rectal carcinoma.The short axis diameter,short-to-long axis diameter ratio,four IVIM-based parameters (ADC,D,D? and f) and six DEC-MRI semi-quantitative parameters (Slope,Maxslope,CER,Washout,TTP,iAUC90 and iAUC180 )were compared between the metastatic (n=28)and non-metastatic (n=27)lymph nodes.Results There were significant statistical significances between the metastatic and non-metastatic lymph nodes in mean short axis diameter (8.87 mm±2.829 mm vs 6.83 mm±1.075 mm),D value(0.824±0.1 13)× 10 -3 mm2/s vs (1.033±0.244)× 10 -3 mm2/s],CER(1.588 ±0.664 vs 1.054 ±0.41 9),iAUC90 (22.89 ± 9.83 vs 13.59 ± 5.34)and iAUC1 80 (49.38±20.1 9 vs 30.31 ± 1 1.67)(P ≤0.001).The short-to-long axis diameter ratio,ADC,D? ,f,Slope,Maxslope,Washout and TTP values did not show significant differences between the two groups(P >0.05).The respectively optimal cut-off value (area under the curve,sensitivity and specificity)for distinguishing metastatic from non-metastatic lymph nodes were as follows:short axis diameter=7.1 mm(0.744,64.2%,85.1%),D=0.906×10 -3 mm2/s (0.821,81.5%,75.0%),CER=1.05(0.749,85.7%,62.9%), iAUC90 =13.42(0.780,85.7%,62.9%),iAUC180 =49.65 (0.770, 50.0%,100%)respecyively.Conclusion Both IVIM-DWI and DCE-MRI are useful for differentiating non-metastatic from metastatic mesorectal lymph nodes in rectal cancer.