自身免疫性胰腺炎的影像特征及其诊断价值

Imaging features of autoimmune pancreatitis and the diagnostic value of imaging examinations

目的探讨自身免疫性胰腺炎（AIP）的影像特征及其在AIP诊断中的价值。方法回顾性分析13例AIP患者的影像和临床资料。结果11例AIP表现为胰腺弥漫性肿大，2例胰头局限性肿大。CT平扫病变密度均均匀。4例在MRT1WI上信号降低、T2WI上信号轻度升高，增强后动脉期病变轻度强化，门脉期及延迟期进一步强化。9例胰腺周围有包膜样结构。横轴位图像上肝内外胆管扩张、胆总管胰腺段狭窄或闭塞10例，胰管未显影11例。6例行MRCP者有4例显示胆总管胰腺段较大范围狭窄或闭塞，胰管节段性狭窄。7例ERCP显示胰管弥漫性、不规则狭窄。胰周静脉受累8例，肾脏多发低密度灶6例，腹膜后纤维化2例，肝门部胆管狭窄1例，肺间质病变1例，强直性脊柱炎1例。结论AIP的影像学征象具有一定特征性，影像检查在AIP诊断中起重要作用。识别胰腺外脏器受累对正确诊断AIP有帮助。

Objective To investigate the imaging characteristics of autoimmune pancreatitis （AIP） and its diagnostic value. Methods Imaging examinations and clinical data of 13 patients with AIP were reviewed retrospectively. Results All patients had enlargement of pancreas either diffusely （ n = 11 ） or focally in pancreatic head （ n = 2 ）. The swollen pancreas was of homogeneous density on CT scan （ n = 13 ）, hypointense on Tl-weighted images and mildly hyperintense on T2-weighted images in 4 patients. It was demonstrated as mild enhancement on artery phase of dynamic imaging and progressive enhancement on portal and delayed phase images. Capsule-like enhanced rim was presented around the pancreas in 9 patients. Stricture or obliteration of the common bile duct located in pancreatic head was found in 10 patients accompanied by intrahepatie bile duct dilation. Pancreatic duct was invisible on axial images in 11 cases. Among the 6 patients underwent MRCP, it was showed diffuse and irregular narrowing of the main pancreatic duct and stricture of common bile duct located in pancreatic head in 4 cases. ERCP showed diffuse and irregular narrowing of the main pancreatic duct in 7 cases. Extra-pancreatic lesion included veins around pancreas involvement in 8 cases ; multiple low density renal lesions in 6 cases; retroperitoneal fibrosis in 2 cases; stricture of hilar duct, interstitial lung disease and ankylosing spondylitis in 1 case, respectively. Conclusions AIP shows some characteristic imaging features, and imaging examinations play an important role in the diagnosis of AlP. Recognition of extra-pancreatic lesions aids in the correct diagnosis of AIP.