高斯分布(单指数、双指数)与非高斯分布DWI模型对低分化胰腺癌的诊断价值

目的探讨不同DWI模型(高斯分布与非高斯分布)对胰腺低分化导管细胞癌的诊断价值。方法收集52例经手术证实的低分化胰腺导管细胞癌患者,术前均行MRI多b值DWI功能成像(1.5T:b值=0、50、100、150、200、500、800、1000、1500、2000 s/mm2),并对不同DWI模型(IVIM、DKI及常规DWI)进行后处理得到相应的慢速表观扩散系数(ADCslow)、快速表观扩散系数(ADCfast)、快速扩散成分所占比例(f值)、平均扩散值(MD值)、平均峰度值(MK值)、常规ADC值(ADCstandard)及常规曲线下面积(AUC值)。采用ANOVA方差分析及Mann-Whitney U检验对数据进行统计分析,并绘制受试者曲线(ROC)来评价不同DWI模型的诊断效能。结果病灶组织ADCstandard、ADCfast、f值低于病灶周围正常组织;而MD值高于周围正常组织。ADCstandard、MD、ADCfast及f值的AUC值分别为0.705、0.665、0.648、0.614。通过回归分析得到ADCstandard与MD值整合后的ROC曲线具有较好的诊断效能(AUC值约0.754)。结论ADCstandard、ADCfast、f值及MK值均可分辨低分化胰腺导管细胞癌的肿瘤组织与周围正常组织。磁共振DWI高斯分布模型与非高斯分布模型联合可以较好地区别肿瘤与非肿瘤病变。

Diagnostic value of DWI MRI between mono-exponential,bi-exponential and nonGaussian kurtosis models in pancreatic ductal adenocarcinoma:a comparative study

Objectives To investigate the diagnostic value of different diffusion-weighted MRI(DWI)models between two Gaussian DWI models including mono-exponential and bi-exponential,and the non-Gaussian kurtosis model in poorly differentiated pancreatic ductal adenocarcinoma.Methods Subjects comprised 52 patients with poorly differentiated pancreatic ductal adenocarcinoma which had been confirmed by surgery.All patients underwent DWI(1.5 T,multi-b values:0,50,100,150,200,500,800,1000,1500,2000 s/mm2).Mean values of DWI-derived metrics ADCstandard,ADCslow,ADCfast,f,MD,MK and ADCstandard were calculated from regions of interest in all tumours and nontumorous parenchyma and compared.ANOVA and Mann Whitney U test was used to compare the MRI paremeters.ROC was used to evaluate the diagnostic efficiency.Results Mean ADCstandard,ADCfast,f and MK values showed significant differences between tumours and non-tumorous parenchyma(P<0.05).AUC for ADCstandard,MD,ADCfast and f were 0.705,0.665,0.648,0.614,respectively.The ROC curve integrated with ADCstandard and MD had better diagnostic efficiency(AUC was about 0.754).Conclusions ADCstandard,ADCfast,f and MK values can differentiate tumours from non-tumorous parenchyma.The combination of Gaussion distribution model and non-Gaussion distribution model has the potential to increase the diagnostic accuracy of DWI in patients with pancreatic ductal adenocarcinoma.