DCE-MRI及IVIM在评估直肠癌患者胸苷酸合成酶表达水平中的价值

The Value of DCE-MRI and IVIM in Evaluating the Expression of Thymidylate Synthase in Rectal Cancer Patients

目的探讨动态增强磁共振成像(DCE-MRI)及体素内不相干运动(IVIM)的定量参数在评估直肠癌患者的胸苷酸合成酶(TS)表达水平中的应用价值。方法回顾性搜集147例经手术病理证实的直肠癌患者,其中TS高表达者98例,TS低表达者49例。所有患者均于术前两周内在本院行盆腔MRI扫描,扫描序列包括常规T1WI、T2WI、DCE-MRI及IVIM。测量直肠癌病灶的各序列定量参数,包括DCE-MRI中的转运常数(K^(trans))、速率常数(Kep)、血管外细胞外容积分数(Ve),IVIM中的表观扩散系数(ADC)、真实扩散系数(D)、假性扩散系数(D^(*))、灌注分数(f)。比较定量参数在TS高表达与低表达组间的差异。采用Logistic回归将有差异的定量参数进行联合,采用受试者工作特征曲线(ROC)分析诊断效能。结果 DCE-MRI及IVIM的定量参数观察者间一致性良好,ICC值均>0.75。TS高表达组K^(trans)、Ve、f值显著高于低表达组,ADC、D值显著低于低表达组。D^(*)、Kep在两组间无显著差异。K^(trans)、Ve、ADC、D、f的AUC值分别为0.642、0.651、0.685、0.604、0.705,最佳诊断阈值分别为0.407 min^(-1)、0.079、0.937×10^(-3)mm^(2)/s、0.737×10^(-3)mm^(2)/s、0.465%,以此阈值诊断TS表达水平的敏感度分别为63.27%、65.31%、63.27%、60.20%、75.51%,特异度分别为57.14%、57.14%、61.22%、57.14%、61.22%。将Ve与ADC进行联合,诊断效能最优,且该组合最精简,AUC值为0.953,敏感度94.90%,特异度100.00%。结论 DCE-MRI定量参数Ve及IVIM定量参数ADC联合,可作为潜在的早期评估直肠癌患者TS表达水平的影像学标志物,辅助临床决策。

Objective To investigate the value of quantitative parameters of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI) and intravoxel incoherent motion(IVIM) in evaluating the expression of thymidylate synthase(TS) in rectal cancer patients. Methods 147 rectal cancer patients confirmed by pathology(high TS expression, n=98;low TS expression, n=49) were retrospectively included. All patients underwent pelvic MRI scan in our hospital within two weeks before surgery. Imaging included conventional T1 WI,T2 WI,DCE-MRI and IVIM. Quantitative parameters of rectal cancer were recorded: K^(trans),Kep,Ve in DCE-MRI,ADC,D,D^(*),f in IVIM. We compared the difference of quantitative parameters between TS high and low expression groups. Logistic regression was used to combine the different quantitative parameters and ROC curve was used to analyze the diagnostic efficacy. Results The quantitative parameters of DCE-MRI and IVIM were consistent among observers with ICC values higher than 0.75. The K^(trans),Ve,and f in the TS high expression group were significantly higher than those in low expression group. TheADC and D were significantly lower than those in the low expression group. There was no significant difference between D^(*) and Kep between the two groups. The AUC values of K^(trans),Ve,ADC,D,and f were 0.642,0.651,0.685,0.604,and 0.705,respectively. The optimal diagnostic thresholds were 0.407 min^(-1)、0.079、0.937×10^(-3)mm^(2)/s、0.737×10^(-3)mm^(2)/s、0.465 %. The sensitivities of using this threshold to diagnose TS expression level were 63.27%,65.31%,63.27%,60.20%,75.51%,and the specificities were 57.14%,57.14%,61.22%,57.14%,61.22%. The combination of Ve and ADC had optimal diagnostic efficiency with AUC of 0.953,sensitivity of 94.90%,and specificity of 100.00%. Conclusion The combination of quantitative parameters in DCE-MRI(Ve) and IVIM(ADC) can be used as a potential early imaging marker for evaluating the expression level of TS,which may assist the clinical decision-making in rectal cancer patients.