胰腺实性假乳头状瘤的MRI影像特征

Imaging findings of solid pseudopapillary neoplasm of the pancreas on MRI

目的:探讨胰腺实性假乳头状瘤的MRI影像特征,提高对该肿瘤MRI征象的认识和诊断能力。方法:回顾性分析17例经手术病理证实的胰腺实性假乳头状瘤患者的MRI资料,所有患者均进行抑脂T1WI和T2WI序列,DWI(b=800s/mm2)和动态增强扫描。两名阅片者独立观察肿瘤一般表现(部位、内部成分、包膜、出血和钙化、信号强度等),测量ADC值和时间-信号强度曲线,与正常胰腺对比,总结该肿瘤MRI特点。结果:17例肿瘤均为单发,边界清楚,大多数类圆形,4例发生在胰头、3例在胰颈、5例在胰体、5例在胰尾。3例实性病灶呈均匀T1WI低、T2WI高和DWI高信号,无包膜和出血且早期均匀并持续强化;14例为囊实性/囊性肿瘤信号混杂且不均匀延迟强化,2例有钙化,4例出血,12例有包膜。肿瘤实性部分DWI上呈高信号,ADC值低于正常胰腺,差别有统计学意义(t=13.67,P<0.001)。所有病例均无继发胰胆管扩张、淋巴结转移及周围结构受侵等表现。结论:SPNP有较为典型的MRI特征,MRI特别是DWI和动态增强扫描对于该肿瘤诊断具有重要价值。

Objective:To investigate the imaging features of solid pseudopapillary neoplasm of the pancreas(SPNP)on MRI,and to enhance the awareness of MR imaging features and diagnostic ability of this rare tumor.Methods:Imaging data of 17 cases of SPNP confirmed by surgery pathology were retrospectively analyzed.All patients underwent fat suppression T 1WI,T 2WI,diffusion weighed imaging(b=800s/mm 2),and dynamic contrast enhancement sequence scanning.The imaging findings,including location,internal component,capsule,hemorrhage,calcification,and signal intensity,etc,were observed carefully by two observers independently.The ADC values and time-signal intensity curves were measured,and were compared with normal pancreatic parenchyma.The imaging features were summarized.Results:The tumors in all patients were solitary.All tumors were well-defined with regular margin and most of them were oval in shape.Four were located in pancreatic head,3 in neck,5 in body and 5 in tail.Three solid tumors showed homogeneously hypointense on T 1WI,hyperintense on T 2WI,hyperintense on DWI and moderate persistent enhancement without capsule and hemorrhage;14 solid-cystic/cystic tumors showed heterogeneously signal intensity on T 1WI,T 2WI and heterogeneous delayed enhancement;calcification was identified in two cases,hemorrhage was shown in four cases,capsule was found in 12 cases.The solid components in the tumors were hyper-intense on DWI,and ADC values decreased compared with the normal pancreatic parenchyma.The differences of ADC values between tumors and normal pancreas was significant statistically(t=13.67,P<0.001).No secondary pancreatic duct dilatation,lymphadenopathy and adjacent organs involvement were detected.Conclusion:The imaging features of SPNP on MRI include,which are helpful in establish the diagnoses.