Autoimmune pancreatitis: imaging findings on contrast-enhanced MR, MRCP and dynamic secretin-enhanced MRCP

Radiol Med. 2009 Dec;114(8):1214-31. doi: 10.1007/s11547-009-0452-0. Epub 2009 Sep 30.

Abstract

Purpose: This study retrospectively determined magnetic resonance (MR), MR cholangiopancreatography (MRCP) and secretin-MRCP findings in patients with autoimmune pancreatitis (AIP).

Materials and methods: The MR examinations of 28 patients with histopathologically proven AIP were reviewed. In 14 cases, secretin-enhanced MRCP was performed. The observers evaluated pancreatic parenchymal enlargement, signal intensity abnormalities, enhancement, vascular involvement, bile-duct diameter and main pancreatic duct (MPD) narrowing (diffuse/focal/segmental). After secretin administration, the presence of the "duct-penetrating" sign was evaluated.

Results: MR imaging showed diffuse pancreatic enlargement in 8/28(29%) cases, focal pancreatic enlargement in 16/28 (57%) cases and no enlargement in 4/28 (14%) cases. The alteration of pancreatic signal intensity was diffuse in 8/28 (29%) cases (eight diffuse AIP) and focal in 20/28 (71%) cases (20 focal AIP). Delayed pancreatic enhancement was present in all AIP, with peripheral rim of enhancement in 8/28 (29%) AIP (1/8 diffuse, 7/20 focal); vascular encasement was present in 7/28 (25%) AIP (1/8 diffuse, 6/20 focal); distal common bile duct narrowing was present in 12/28(43%) AIP (5/8 diffuse, 7/20 focal). MRCP showed MPD narrowing in 17/28 (61%) AIP (4/8 diffuse, 15/20 focal), MPD dilation in 8/28(29%) AIP (3/8 diffuse, 5/20 focal) and normal MPD in 1/8 diffuse AIP. Secretin-MRCP showed the duct-penetrating sign in 6/14(43%) AIP (one diffuse AIP with MPD segmental narrowing, five focal AIP with MPD focal narrowing), demonstrating integrity of the MPD.

Conclusions: Delayed enhancement and MPD stenosis are suggestive for AIP on MR and MRCP imaging. Secretin-enhanced MRCP is a problem-solving tool in the differential diagnosis between focal AIP and ductal adenocarcinoma.

MeSH terms

  • Adult
  • Aged
  • Autoimmune Diseases / diagnostic imaging*
  • Autoimmune Diseases / pathology
  • Cholangiopancreatography, Endoscopic Retrograde*
  • Cholangiopancreatography, Magnetic Resonance*
  • Contrast Media*
  • Diagnosis, Differential
  • Female
  • Gastrointestinal Agents
  • Hormones
  • Humans
  • Male
  • Middle Aged
  • Pancreatic Neoplasms / diagnostic imaging
  • Pancreatitis / diagnosis
  • Pancreatitis / diagnostic imaging*
  • Retrospective Studies
  • Risk Factors
  • Secretin*
  • Sensitivity and Specificity

Substances

  • Contrast Media
  • Gastrointestinal Agents
  • Hormones
  • Secretin