小视野高分辨DWI对胰腺实性病变的鉴别诊断价值

Value of reduced field of view DWI in differentiating solid pancreatic focal lesions

目的探讨小视野高分辨扩散加权成像（rFOV DWI）对胰腺实性占位的鉴别诊断价值。方法收集139例胰腺实性占位患者，其中胰腺导管腺癌（PDAC）105例，神经内分泌肿瘤（NET）16例，肿块型慢性胰腺炎（MFCP）7例，实性假乳头状瘤（SPT）11例。招募38名健康成年志愿者作为对照组。行包括单次激发平面回波成像（ss-EPI）DWI、rFOV DWI（b值为0和600 s/mm2）的MRI检查。采用四分法从解剖结构的可视性、胰腺病灶对比度、运动及磁敏感伪影3方面评估rFOV DWI及ss-EPI DWI图像质量，通过工作站自带软件测量感兴趣区（ROI）的表观扩散系数（ADC）值。比较两种DWI的图像质量及ADC值在各胰腺疾病及正常胰腺间的差异。绘制ADC值的受试者工作特征（ROC）曲线，评价PDAC与其他胰腺良性肿块及正常胰腺的差异。结果b值为0和600 s/mm2的rFOV DWI在显示胰腺解剖结构、病灶对比度、伪影评分均优于ss-EPI DWI（b＝0 s/mm2时为2.99±0.51比2.79±0.64、2.37±0.48比1.81±0.63、3.17±0.56比2.91±0.60；b＝600 s/mm2时为3.63±0.50比3.32±0.56、3.45±0.50比3.01±0.49、3.74±0.44比3.12±0.37），差异均有统计学意义（P值均〈0.001）。PDAC、NET、MFCP、SPT、正常胰腺rFOV DWI获得的ADC值分别为（1.38±0.17）×10－3、（1.22±0.35）×10－3、（1.29±0.13）×10－3、（1.04±0.38）×10－3、（1.86±0.15）×10－3mm2/s；ss-EPI DWI的ADC值分别为（1.73±0.24）×10－3、（1.63±0.39）×10－3、（1.58±0.19）×10－3、（1.25±0.26）×10－3、（2.04±0.20）×10－3mm2/s，各组间的差异及同组内两ADC值间的差异均有统计学意义（P值均〈0.001）。MFCP与PDAC、NET与MFCP、MFCP与SPT间rFOW DWI的ADC值的差异及MFCP与PDAC、PDAC与NET、SPT与MFCP间ss-EPI DWI的ADC值差异无统计学意义，而其他两两组间差异均有统计学意义（P值均〈0.05）。PADC与正常胰腺rFOV DWI和ss-EPI DWI的ROC曲线下面积（AUC）分别为0.983（95%CI0.944～0.998）和0.889（95%CI0.822～0.936），差异有统计学意义（P＝0.0004），而PDAC与所有良实性病变的rFOV DWI和ss-EPI DWI的ADC值的AUC分别为0.799（95%CI0.719～0.864）和0.755（95%CI0.672～0.827），差异无统计学意义。结论rFOV DWI显著提高DWI图像质量，并且对胰腺导管腺癌的诊断效能更佳。

ObjectiveTo study the value of reduced field-of-view （rFOV DWI） in differentiating patients with solid pancreatic focal lesions.Methods139 patients with solid pancreatic mass were enrolled, including 105 patients with pancreatic ductal acinar carcinoma （PDAC）, 16 patients with neuroendocrine neoplasms, 7 patients with mass forming chronic pancreatitis （MFCP） and 11 patients with solid papillary tumor （SPT）. 38 healthy adult volunteers served as controls, and underwent single stimulated echo planar imaging （ss-EPI）DWI and rFOV DWI（b value=0 and 600 s/mm2）MRI examination. Quartation method was used to evaluate the image quality of ss-EPI）DWI and rFOV DWI in the three terms of the visibility of anatomical structure, contrast of pancreatic lesions, motion and the susceptibility artifacts during MRI. Work station self-carried software was used to measure the ADC value of the region of interest （ROI）. The image quality and ADC values of different pancreatic diseases and normal pancreas were compared. ROC curve for ADC value was drawn to evaluate the difference among PDAC, other benign pancreatic masses and normal pancreas.ResultsAt b value of 0 and 600 s/mm2, rFOV DWI was superior to ss-EPI DWI in terms of showing pancreatic anatomic structure, the contrast of the lesion and the score evaluation for susceptibility artifacts（b=0 s/mm2 2.99±0.51 vs 2.79±0.64, 2.37±0.48 vs 1.81±0.63, 3.17±0.56 vs 2.91±0.60; b=600 s/mm2 3.63±0.50 vs 3.32±0.56, 3.45±0.50 vs 3.01±0.49, 3.74±0.44 vs 3.12±0.37）, and the differences were statistically significant （P〈0.001）. ADC values of PDAC, NET, MFCP, SPT and normal pancreas were （1.38±0.17）×10-3, （1.22±0.35）×10-3, （1.29±0.13）×10-3, （1.04±0.38）×10-3 and（1.86±0.15）×10 -3 mm2/s for rFOV DWI, and（1.73±0.24）×10-3, （1.63±0.39）×10-3, （1.58±0.19）×10-3, （1.25±0.26）×10-3 and（2.04±0.20）×10-3mm2/s for ss-EPI DWI. The difference on ADC values among different groups and within one group were all statistically significant （P〈0.001）. There were no statistical significant differences on ADC values between MFCP and PDAC, between MFCP and SPT as well as on ss-EPI DWI ADC values between PDAC and NET, but statistical differences were found between other two groups （P〈0.05）. The area under the ROC curve of rFOV and ss-EPI DWI was 0.983 （95% CI 0.944-0.998） and 0.889 （95% CI 0.822-0.936）, respectively, and the difference was statistically significant （P=0.0004）, but rFOV DWI and ss-EPI DWI ADC values for PDAC and all benign solid diseases were 0.799 （95% CI 0.719-0.864） and 0.755 （95% CI 0.672-0.827）, and the difference was not statistically significant.ConclusionsrFOV DWI could significantly enhance the quality of DWI images, and its diagnostic efficacy was much better than ss-EPI DWI.