MRI features and follow-up analysis of autoimmune pancreatitis

doi:10.19300/j.2016.L3365

Abstract：Objebtive To explore MRI features of autoimmune pancreatitis (AIP) at initial diagnosis and follow-up periods. Methods Clinical and MRI appearances in 11 patients with AIP were observed, and MRI features before and after steroid treatment in different periods were retrospectively analyzed. The difference in pancreatic size between initial and follow-up exam was tested with paired samples t test, comparison was done also for measures at initial and after steroid treatment. Results On initial MRI, pancreatic parenchyma showed diffuse enlargement in 9 patients, focal enlargement at the pancreatic head in 1, and focal mass at the body in 1. The involved pancreas appeared as hypo-intense on T 1-weighted images in all patients, hyper-intense on T2-weighted images in 10, and iso-intense in 1. Hypo-intense rim around the pancreas was seen in 4 patients. Pancreatic duct was not visible in 7 patients, intermittent display in 2, beading change in 1, and displacement at the body in 1. Thickening of intra-pancreatic bile duct wall was seen in 9 patients. Follow-up in natural process, pancreatic enlargement and MRI signal change were similar to the initial lesions in 5 patients, progression of bile duct involvement was noted in 4. Following steroid treatment, the pancreas swelling, signal abnormalities, thickening of bile duct wall became normal in 6 patients, hypo-intense rim around the pancreas disappeared in 4 patients. Pancreatic lesions recurred in 3 patients. The lesion features in recurrence were similar to those in the original. In addition, a pseudocyst occurring in front of pancreatic body and tail was found in 1 patient. There was no significant difference in pancreatic size between initial and followup exams in the patients with natural process, and there was statistical significance before and after steroid treatment. Conclusion MRI features of AIP were characteristic, and MRI can be used in diagnosis, evaluation of steroid effect, long-term follow-up and identifying recurrence.