IgG4相关性自身免疫性胰腺炎影像学表现

Imaging findings of IgG4-related autoimmune pancreatitis

目的分析IgG4相关性自身免疫性胰腺炎(autoimmune pancreatitis,AIP)的CT和MRI表现,以提高对该病影像学特征的认识,减少影像学误诊。方法回顾性分析47例IgG4相关性AIP患者的临床资料,其中33例行CT平扫及增强扫描,24例行MRI平扫及增强扫描、MRCP检查,10例联合行CT及MRI检查,观察病变胰腺的形态、密度/信号改变及强化特征、胰腺周围及胰管改变、胰腺外表现。结果47例患者中,CT及MRI检查共观察到胰腺弥漫性肿大呈“腊肠状”27例,局灶性肿大20例;CT平扫病变表现为均匀一致的略低密度,增强扫描动脉期病变区呈不均匀斑片状强化,门脉期和延迟期病变区呈现较均匀的延迟渐进性强化;MRI检查病变表现为T 1 WI-FS呈不均匀稍低信号,T_(2)WI呈稍高信号,增强扫描早期病灶不均匀轻度强化,延迟扫描呈较均匀延迟渐进性强化;CT及MRI检查28例胰腺周围见包膜样边缘,即“胶囊征”,增强扫描呈轻中度延迟强化;MRCP检查示10例患者可见主胰管节段性狭窄,上游胰管局限性轻度扩张;CT及MRI检查共观察到30例患者表现为胆管系统改变,可见胆总管胰腺段管壁增厚、狭窄伴延迟强化,MRCP检查呈“鸟嘴样”改变,上游肝内外胆管不同程度扩张。结论IgG4相关性AIP的CT和MRI表现具有一定的特征性,结合影像学表现及实验室相关检查有助于提高该病的诊断水平。

Objective To analyze the computed tomography(CT)and magnetic resonance imaging(MRI)findings of immunoglobulin G4(IgG4)-related autoimmune pancreatitis(AIP),to improve the understanding of the imaging features of this disease,and to reduce imaging misdiagnosis.Methods A retrospective analysis was performed on the clinical data of 47 patients with IgG4-related AIP,among whom 33 underwent plain CT scan and contrast-enhanced CT scan,24 underwent plain MRI scan,contrast-enhanced MRI scan,and magnetic resonance cholangiopancreatography(MRCP)examination,and 10 underwent combined CT and MRI examination to observe the morphology,changes in density/signal,contrast enhancement characteristics of the diseased pancreas,the peripancreatic and pancreatic duct changes,and the manifestations out of the pancreas.Results The CT and MRI scans showed that among the 47 patients,27 had a“sausage-like”,diffusely enlarged pancreas and 20 had a focally enlarged pancreas.The plain CT scan showed a uniform and slightly low density;the contrast-enhanced CT scan of the lesion showed an inhomogeneous patchy enhancement in arterial phase,and a uniformly delayed progressive enhancement in portal vein phase and delayed phase.The MRI scan of the lesion showed inhomogeneous and slight hypointensity on T 1 WI-FS and slight hyperintensity on T_(2)WI,the contrast-enhanced MRI scan showed an inhomogeneous mild enhancement in the early stage and a uniformly delayed progressive enhancement on delayed scan.The CT and MRI scans showed that 28 patients had capsule-like edges around the panc-reas,namely“capsule sign”,with a mild to moderate delayed enhancement on contrast-enhanced images.The MRCP showed that 10 patients had segmental stenosis of the main pancreatic duct and localized mild dilatation of the upstream pancreatic duct.The CT and MRI scans showed that 30 patients had changes in the bile duct system,with wall thickening,stenosis,and delayed enrichment of the pancreatic segment of common bile duct.The MRCP showed“beak-like”changes,and dilatation of upstream intrahepatic and extrahepatic bile ducts to varying degrees.Conclusion The CT and MRI findings of IgG4-related AIP have certain characteristics.The combination of imaging findings and relevant laboratory tests can help improve the diagnosis of this disease.