胰腺内副脾与G1级神经内分泌肿瘤的MRI鉴别诊断

MRI differential diagnosis between intrapancreatic accessory spleen and G1 grade pancreatic neuroendocrine tumor

目的:总结胰腺内副脾(IPAS)与G1级神经内分泌肿瘤(PNENs)的MRI特征,明确两者的影像学征象。方法:回顾性分析2013年1月至2019年12月间海军军医大学第一附属医院收治的11例经手术病理或99mTc热变性红细胞显像证实的IPAS患者和9例经手术病理证实的发生在胰尾的G1级PNENs患者资料。观察IPAS组和PNENs组病灶的MRI特征,包括病灶形态、大小、是否突出于胰腺轮廓之外、是否囊变、平扫T 2WI信号、DWI信号、多期强化方式及有无假包膜等,比较两组病灶表现特征的差异。结果:IPAS组和PNENs组在病灶突出于胰腺轮廓之外、T 2WI及DWI信号、多期强化方式、假包膜的差异上均有统计学意义(P值均<0.05)。PNENs组病灶(9/9)较IPAS组病灶(3/11)更容易突出于胰腺轮廓之外;PNENs组病灶T 2WI及DWI信号略高于IPAS组病灶,其T 2WI、DWI高信号占比分别为6/9、4/9,而IPAS组均为0;PNENs组病灶多期强化更倾向于强化范围前后一致(6/9),而IPAS组病灶则以强化范围前后不一为主(10/11);PNENs组病灶增强后均可见假包膜,IPAS组病灶增强后均无假包膜。结论:病灶突出于胰腺轮廓之外、T 2WI及DWI信号特点、多期强化方式及假包膜是IPAS与G1级PNENs的重要鉴别征象。

Objective To summarize the MRI features of intrapancreatic accessory spleen(IPAS)and G1 grade pancreatic neuroendocrine neoplasms(PNENs),and clarify the radiological features for differential diagnosis.Methods The data of 11 patients with IPAS confirmed by surgical pathology or 99mTc thermal denatured red blood cell imaging and 9 patients with G1 grade PNENs confirmed by surgical pathology in the tail of pancreas from January 2013 to December 2019 admitted in First Affiliated Hospital of Navy Medical University were retrospectively analyzed.MRI features of IPAS group and PNENs group,including shape,size,whether it protruded beyond the contour of the pancreas,cystic degeneration,plain scan of T2WI,DWI signal,multistage enhancement mode,false capsule,etc.were studied and compared.Results There was significantly statistical difference between the two groups in the terms of contour protrusion,T2WI and DWI signals,multistage enhancement,and pseudomembrane(all P<0.05).Protruded lesion was more common in the PNENs group(9/9 cases)than in the IPAS group(3/11).The T2WI and DWI signals of lesions in the PNENs group were slightly higher than those in the IPAS group,and the proportion of high T2WI and DWI signal lesions in the PNENs group was 6/9 cases and 4/9 cases,respectively,while the proportion of high T2WI and DWI signal lesions in the IPAS group was 0/11 cases.Multistage enhancement of lesions in the PNENs group was more likely to be consistent(6/9),while lesions in the IPAS group were more inconsistent(10/11).In the PNENs group,all lesions showed false envelope after enhancement(9/9),while in the IPAS group,no false envelope was observed after enhancement(0/11).Conclusions The presence of protruded lesions,the characteristics of T2WI and DWI signals,the mode of multiphase enhancement and the false envelope were essential signs for differentiating IPAS and G1 grade PNENs.