Autoimmune pancreatitis: study of MRI manifestation
NI Rui-jun1, XU Shun-liang1, RUAN Ling-xiang1, WANG Bo-yin2
1.The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China;2.Shaoxing City People’s Hospital, Shaoxing Zhejiang 312000, China
Abstract：Objective: To investigate the MR imaging findings of autoimmune pancreatitis(AIP). Methods: The MR data of 8 patients with AIP were retrospectively reviewed. Plain MR and dynamic contrast-enhanced three-phase MR scanning was performed on 8 patients. Fat-suppressed T2WI, T1WI, in- and out-phase T1WI and dynamic contrast-enhanced data were analyzed, focusing on signal intensity of abnormal pancreas parenchyma, enhancement patterns of the abnormal pancreas and microstructure alteration. The signal intensity value of abnormal pancreas parenchyma on plain-scanning and each phase of dynamic contrast-enhanced scanning were measured, compared to that of controls(n=25, with normal pancreas). Results: Five patients showed diffuse swelling of the pancreas and 3 patients showed segmental enlargement of pancreas. 6 patients showed psuedocapsule like around the pancreatic body and tail. Main pancreatic duct in abnormal pancreas were invisible. The signal intensity on each sequence was lower than that of normal pancreas: abnormal pancreas showed homogeneous hypointensity on fat-suppressed(or not) T2WI and not fat-suppressed T1WI, and heterogeneous multiscale hypointensity on fat-suppressed T1WI; Some funicular slightly hyperintensity area could be seen in the abnormal pancreas on fat-suppressed T1WI. Funicular and micronodular enhanced area could be seen in 6 patients with AIP ahead of time. Progressively enhancement was found in 8 patients with AIP, different from the controls. Conclusion: There is typical MR imaging features of AIP. Fat-suppressed T1WI and MR dynamic contrast-enhanced scanning play an important role in discovering the alteration of microstructure of AIP. AIP can be diagnosed correctly through MR examination.
2011, Vol. 22 
