胰腺实性假乳头状肿瘤的CT和MRI诊断

目的探讨CT和MRI在胰腺实性假乳头状肿瘤中的诊断价值。方法回顾性分析14例经手术或病理证实的胰腺实性假乳头状肿瘤的CT和MRI表现。本组11例行CT扫描,9例行MRI扫描。分析肿瘤的位置、大小、形态、密度、信号特征及强化方式。结果发生于胰头部3例,胰头颈部1例,胰颈部1例,胰体部1例,胰体尾部5例,胰尾部3例。本组14例病灶均为单发。肿瘤呈圆形或类圆形10例,不规则分叶状4例。肿瘤最大径线2.1~10.8cm（平均7.77cm）。CT平扫均显示密度不均,其内见大小不一斑片状囊变、坏死区,增强肿瘤实质部分动脉期轻中度强化,实质期、延迟期中度-明显强化。所有病例增强后均强化不均,呈进行性强化,3例病灶内见斑片状出血灶,2例病灶内有钙化,2例侵犯邻近胰腺,1例伴肝转移。MRI多表现为较大的边界清楚或不清楚囊实性肿块,T1WI呈等低信号,T2WI呈中等-高信号或混杂信号,DWI呈稍高信号,增强肿瘤实质部分呈中等度持续性强化。结论胰腺实性假乳头状肿瘤的CT和MRI表现具有一定特征性,CT和MRI的密度或信号变化能够反映病灶组织学成分的不同,CT和MRI在实性假乳头状肿瘤的诊断与鉴别、观察肿块与周围组织的关系方面扮演重要角色。

CT and MRI manifestations of solid pseudopapiUary tumor of the pancreas

Objective To determine diagnostic value of CT and MRI in solid pseudopapillary tumor（SPT） of the pancreas.Methods CT and MRI findings of 14 patients with surgically or pathologically proven solid pseudopapillary tumor of the pancreas were analyzed retrospectively. Among them, 11 patients underwent CT scan, and 9 patients un- derwent MRI scan. Tumor location, size, shape, density, signal intensity and enhancement pattern were reviewed on CT and MRI.Results Three SPT were located in the pancreatic head, 1 in the pancreatic head and neck, 1 in the pancreatic neck, 1 in the pancreatic body, 5 in the pancreatic body and tail and B in the pancreatic tail. Tumor size ranged from 2.1 to 10.8cm（mean=7.77cm）. The lesions showed single mass in all 14 eases.The shape of the masses showed oval or rounded（10/14）, and irregular（4/14）. Unenhanced CT images displayed heterogeneous density mass with patchy, cystic change and necrotic foci in all cases. Contrast-enhanced CT images demonstrated mild-medium enhancement in the arterial phase, medium-marked enhancement in the parenchymal and delayed phase. The tumors revealed a durative heterogeneous enhancement mass with patchy bleeding loci in 3 cases, calcification in 2 cases, hepatic metastasis in 1 case and invasion of adjacent pancreas in 2 cases. At MRI, SPF often manifests as a large mass of solid and cystic mixed components with ill- or well-defined margins. The tumors showed hypo-or iso-intensity on Ti-weighted image, intermediate to high signal intensity or heterogeneous mixed intensity on T2-weighted images, slightly high signal intensity on DW images and medium progressive enhancement of solid components on con- trast-enhanced T1-weighted images. Conclusion The CT and MRI features of solid pseudopapillary tumor of the pancreas were specific. The density or signal alteration of CT and MRI can reflect different histological components of the lesions. CT and MRI are valuable in discovering and differentiating SPT, detecting the relation between the lesions and