A study on the imaging characteristics of autoimmune pancreatitis / 中华普通外科杂志

ABSTRACT

ObjectiveTo investigate the CT and MRI imaging characteristics of autoimmune pancreatitis and its clinical value.MethodsFourteen patients(13males, 1female, mean age 58.3 years) with autoimmune pancreatitis proved histopathologically or clinically were enrolled in the study.Clinical data was studied retrospectively.Among those patients,CT was performed on 12 cases and MR imaging was performed on 8 patients,6 patients underwent both CT and MR imaging.ResultsAll 14 patients had enlargement of the pancreas,which could be divided into three types including diffuse type ( n =7 ),focal type ( n =5 ) and mixed type ( n =2 ).On plain CT the pancreas was of isodensity ( n =5 ) or mild hypodensity ( n =7).In one case there was several small hypodensity cystic lesions within and around the pancreas that was rarely seen in other autoimmune pancreatitis cases.Pancreatic lesions as shown by MRI were all mildly hypointense on T1WI and mildly hyperintense on T2WI,all displayed lesions were detected as high-signal intensity areas on DWI. By medium contrast,autoimmune pancreatitis lesions demonstrated “ snow-like” heterogeneously decreased enhancement on artery phase of dynamic contrast enhanced imaging and then showed gradually delayed enhancement on portal venous phase and later phases.“Capsule-like” rim was present around the autoimmune pancreatitis lesions in 9 cases.Main pancreatic duct was irregular in shape in 4 cases and slightly dilated in 5 patients.Strictures of lower common bile duct and upper bile duct dilatation as well as thickening and enhancement of the bile duct wall were found in 9 cases.Peripheral vascular involvement was seen in 4 cases. Abdominal lymphadenopathy at hepatic portal was observed in 1 patient.Two cases showed tiny decreased enhancement lesions in the kidneys.Steroid therapy was given in 10 cases,all pancreatitis lesions ameliorated as showed by follow-up imaging examinations.ConclusionsAIP specific CT and MRI imaging findings are common in most patients which help establish the diagnosis and differential diagnosis of AIP.