中老年人自身免疫性胰腺炎的磁共振表现

Magnetic resonance imaging characteristics of autoimmune pancreatitis in middle-aged and elderly patients

目的探讨中老年人自身免疫性胰腺炎（AIP）的磁共振（MRI）特征。方法17例经组织学或类固醇激素治疗证实的中老年AIP患者，均接受MRI检查，对患者的临床和MRI资料进行回顾性分析。结果17例中老年AIP中，13例AIP表现为胰腺弥漫性肿大，4例为局限性肿大或局限性信号异常。病变T1WI上呈明显低信号，在T1WI上呈轻度高信号，动脉期强化减弱但呈现明显的延时强化。13例在胰腺病变周围环绕包膜样结构。15例AIP伴有胰腺段胆总管的狭窄，5例胰胆管磁共振显示胰管不规则狭窄。Ⅱ例AIP的平均表观扩散系数值为1．64×10^-3mm^2／s。结论AIP好发于中老年人；其MRI特征包括胰腺呈香肠样或香蕉样肿大、病变胰腺周围延迟强化的包膜样影、胰管弥漫不规则狭窄等，MRI既可用于诊断AIP，也是评价其疗效的重要手段。

Objective To investigate magnetic resonance imaging（MRI） characteristics of autoimmune pancreatitis（AfP） in middle aged and elderly patients. Methods MR/ were performed in 17 middle aged and elderly patients with AIP proved histopathologically or clinically. All clinical and MRI data were reviewed. Results Of 17 cases, MRI showed diffuse enlargement of the pancreas in 13 cases, and focal lesions in 4 cases. Swelled pancreas was hypointense on T1 weighted images, mildly hyperintense on T2-weighted images, decreased enhancement on artery phase of dynamic imaging, and moderate enhancement on delayed phase images. Capsule like enhanced rim was found around swelled pancreas in 13 patients. Stricture of distal common bile duct was present in 15 patients, and diffuse irregular narrowing of the main pancreatic duct was showed in 5 cases. The mean apparent diffusion coeffieient（ADC） value of AIP was 1.64 × 10^-3 mm^2/s in 13 cases. Conclusions AIP occurs more often in middle-aged and elderly people. AIP shows some characterized MRI findings including swelled pancreas looking like banana or sausage, delayed enhanced capsule-like rim around the lesion and diffuse irregular narrowing of pancreatic duct. MRI will play an important role not only in the diagnosis of AlP, but also in evaluating curative effect of AIP.