胰腺实性假乳头状瘤的影像学表现与鉴别诊断

Solid pseudopapillary tumor of the pancreas:imaging diagnosis and differentiation

目的探讨胰腺实性假乳头状瘤(SPTP)的CT、MRI、18F-FDGPET/CT表现及影像学在鉴别诊断中的价值。方法回顾性分析经手术病理证实的8例SPTP的影像学资料。8例均接受CT平扫及增强扫描,2例接受MRI平扫及增强扫描,1例接受PET/CT检查。结果8例CT平扫均呈体积较大的囊实性肿块,其中实性成分为主型2例,囊性成分为主型3例,囊实性相间型3例。6例包膜完整,7例外生性生长,2例见出血,1例见钙化。2例MRI平扫实性成分在T1WI呈低信号、T2WI呈稍高信号,囊性成分呈长T1、长T2信号,包膜在T1WI和T2WI均呈低信号,MRI发现一处CT未能显示的出血灶。实性成分及包膜在CT、MR增强扫描中均呈延迟强化,但实性成分的强化程度始终低于胰实质,而包膜的强化程度在门静脉期和延迟期高于胰腺实质。1例PET/CT实性成分呈半环形、不均匀FDG代谢增高灶。结论SPTP的影像学特征为包膜完整、体积较大、可伴出血和钙化的囊实性肿块,其实性成分及包膜增强后延迟强化,且实性成分FDG代谢增高等。综合影像检查有助于鉴别诊断。

Objective To investigate the role of CT, MRI and PET/CT in diagnosis and differentiation of solid pseudopapillary tumor of the pancreas （SPTP）. Methods Imaging findings in 8 patients （7 females and 1 male, mean age 32.1 years） with histopathologically proved SPTP were analyzed retrospectively. CT scanning was performed in all 8 patients, MRI and PET/CT were respectively studied in 2 and 1 patients, respectively. Results All patients cystic-solid mass with comparatively large volume on CT scanning was detected in all 8 patients, including 2 lesions of predominantly solid component, 3 lesions of predominantly cystic component and 3 lesions of alternately solid and cystic component. Complete capsule, exophytic lesion, hemorrhage and calcification were found in 6, 7, 2 and 1 lesions, respectively. The solid part of 2 lesions showed low signal intensity on T1WI and slightly high signal intensity on T2WI, the cystic part showed low signal intensity on TIWI and high signal intensity on T2WI. The capsule showed low signal intensity on TlWI and T2WI. One lesion with hemorrhage was detected by MRI, but not by CT. The solid part and capsule of SPTP presented the feature of delayed enhancement after injecting contrast medium. The solid part enhanced less than the pancreatic parenchyma did in all three phases, while the capsule enhanced more than pancreatic parenchyma did in venous phase and delayed phase. The solid part of one ease showed a high uptake loci like semiring-shap on PET/CT with 18 F-FDG. Conclusion Cystic-solid mass with comparatively large volume, complete capsule, hemorrhage, calcification and delayed enhancement of the capsule and the solid part showing high FDG uptake are the imaging features of SPTP. Multiple imaging methods are favorable to differentiation diagnosis.