胰腺非高强化神经内分泌肿瘤与导管腺癌的MRI鉴别诊断

Differential diagnosis of non-hypervascular pancreatic neuroendocrine tumor and pancreatic ductal adenocarcinoma by MRI

探讨MRI平扫及动态增强扫描在鉴别动脉期非高强化胰腺神经内分泌肿瘤(PNET)和胰腺导管腺癌(PDAC)中的价值.方法回顾性分析2010年1月至2018年11月北京大学第三医院经过病理证实的35例PNET(共45个病灶)和52例PDAC(共53个病灶)的MRI平扫及动态增强扫描(包括动脉期、静脉期、延迟期)特点.根据动脉期强化程度将PNET病灶分为高强化组和非高强化组.记录非高强化组PNET和PDAC组病变的位置、大小、数量及边缘、平扫及增强各期信号特点.观察胰管、胆管及胰腺形态、血管侵犯及周围浸润情况及其他脏器转移情况.两组病变信号强度比值比较使用独立样本t检验.病变各征象及继发征象的比较使用χ^2检验.结果高强化组共20个病灶,非高强化病灶共25个病灶.非高强化PNET组病灶动脉期、静脉期、延迟期强化程度均高于PDAC组(P<0.01).静脉期PNET组等高强化病灶数量(20/25)和延迟期等高强化病灶数量(23/25)多于PDAC组(P<0.01);17个病灶边缘较规则(P<0.01);主胰管狭窄患者(8/25)明显少于PDAC组(P<0.01);继发远端胰管扩张(6/25)较少(P<0.01),扩张程度较轻,远端胰腺萎缩(5/25)较少(P<0.05);仅2例累及胆总管;胰周浸润(8/25)较PDAC组少(P<0.01),血管侵犯(8/25)较PDAC组少(P<0.05).结论边缘规则,静脉期及延迟期高或等强化,胰管无扩张或轻度扩张、胰腺无萎缩更支持动脉期非高强化PNET的诊断,有助于和PDAC鉴别.

Objective To investigate the value of MR unenhancement and dynamic enhancement scans for distinguishing non-hypervascular pancreatic neuroendocrine tumor(PNET)from pancreatic ductal adenocarcinoma(PDAC).Methods Thirty five patients(45 lesions)with pathologically confirmed PNETs and 52 patients(53 lesions)with PDACs were retrospectively analyzed before surgery.All patients underwent MR unenhanced and dynamic enhanced scans(including arterial,venous and delayed phase).Based on arterial enhancement,PNETs were divided into hypervascular and non-hypervascular lesions.The morphologic characteristics(including location,size,quantity,margin and signal intensity)and enhancement patterns of non-hypervascular PNETs and PDACs were evaluated.Involvement of the pancreatic duct and bile duct,vascular invasion,peripancreatic infiltration and other organs metastasis were observed.Independent sample ttest was used to compare signal intensity ratio of nonhypervascular PNET and PDAC.Chi-square test was used to compare MRI characteristic and secondary signs.Results PNET included 20 hypervascular and 25 nonhypervascular lesions.Enhancement degree of non-hypervascular PNET was higher than PDAC in the arterial,venous and delayed phase(P<0.01).Non-hypervascular PNET showed significantly higher frequencies(P<0.01)of venous hyper-or isoenhancement(20/25),delayed hyper-or isoenhancement(23/25)and a well-defined margin(17/25),but lower frequencies of ductal stricture and dilatation(P<0.01),pancreas atrophy(P<0.05),bile duct stricture(2/25),peripancreatic infiltration(8/25,P<0.01)and vascular invasion(8/25,P<0.05),when compared with PDAC.Conclusion A well-defined margin,hyper-or isoenhancement in the venous and delayed phase,and without ductal dilatation and pancreas atrophy are more common in non-hypervascular PNET,which may be distinguished from PDAC.