title: Morphologic patterns of autoimmune pancreatitis in CT and MRI.
abstract: OBJECTIVE
  To retrospectively evaluate the morphologic characteristics of autoimmune pancreatitis (AIP) using MRI and CT.
  
  
  METHODS
  86 dynamic contrast-enhanced CT and MRI scans in 36 AIP patients were evaluated regarding: different enlargement types, abnormalities of the main pancreatic duct (MPD), morphology of the parenchyma and other associated findings.
  
  
  RESULTS
  3 types of enlargement were found: (1) a focal type (28%), (2) a diffuse type (involving the entire pancreas, 11%) and (3) a combined type (56%). The MPD was usually dilated together with focal or diffuse narrowing in 67% (24/36). Unenhanced MRI showed AIP area in 56% (mostly T(1) hypo- and T(2) hyperattenuating), and CT in 10% (hypoattenuating). The arterial phase depicted similar patterns for CT and MRI (hypoattenuating in 58 and 52%, respectively). Venous and late venous phase patterns were usually hyperattenuating in MRI (65 and 74%, late enhancement), while CT mostly showed no signal differences (isoattenuating in 57 and 75%), yielding significant differences between CT and MRI for the venous (p < 0.0001) and the late phase (p = 0.025). Miscellaneous findings were: rim sign (25%), pseudocysts (8%) and infiltration of large vessels (11%).
  
  
  CONCLUSIONS
  The 'late-enhancement' sign seems to be a key feature and is best detectable with MRI. MRI may be recommended in the diagnostic workup of AIP patients. and IAP.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg, Germany. Christoph.Rehnitz@med.uni-heidelberg.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Rehnitz
authors.forename: Miriam
authors.initials: M
authors.lastname: Klauss
authors.forename: Reinhard
authors.initials: R
authors.lastname: Singer
authors.forename: Robert
authors.initials: R
authors.lastname: Ehehalt
authors.forename: Jens
authors.initials: J
authors.lastname: Werner
authors.forename: Markus W
authors.initials: MW
authors.lastname: Büchler
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Lars
authors.initials: L
authors.lastname: Grenacher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000000981:diagnostic imaging / Q000473:pathology*; D010183:Pancreatic Ducts / Q000000981:diagnostic imaging / Q000473:pathology; D010195:Pancreatitis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology*; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed