ABSTRACT
Objective To investigate magnetic resonance imaging(MRI) characteristics of autoimmune pancreatitis(AIP) in middle-aged and elderly patients. Methods MRI were performed in 17 middle-aged and elderly patients with AlP 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 coefficient(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 AIP, but also in evaluating curative effect of AIP.