Diffusion-weighted magnetic resonance imaging in autoimmune pancreatitis.

Abstract

PURPOSE:

The aim of this study was to investigate the usefulness of diffusion-weighted magnetic resonance imaging (DWI MRI) for the diagnosis and evaluation of autoimmune pancreatitis (AIP).

MATERIALS AND METHODS:

A total of 4 consecutive patients with AIP, 5 patients with chronic alcoholic pancreatitis (CP), and 13 patients without pancreatic disease (controls) were studied. DWI was performed in the axial plane with spin-echo echo-planar imaging single-shot sequence. Apparent diffusion coefficients (ADCs) were measured in circular regions of interest in the pancreas. In AIP patients, abdominal MRI was performed before, and 2-4 weeks after steroid treatment. Follow-up study was performed chronologically for up to 11 months in two patients. The correlation between ADCs of the pancreas and the immunoglobulin G4 (IgG4) index (serum IgG4 value/serum IgG4 value before steroid treatment) was evaluated.

RESULTS:

In the AIP patients, DWI of the pancreas showed high signal intensity, and the ADCs of the pancreas (mean +/- SD: 0.97 +/- 0.18 x 10(-3) mm(2)/s) were significantly lower than those in patients with CP (1.45 +/- 0.10 x 10(-3) mm(2)/s) or the controls (1.45 +/- 0.16 x 10(-3) mm(2)/s) (Mann-Whitney U-test, P < 0.05). In one AIP patient with focal swelling of the pancreas head that appeared to be a mass, DWI showed high signal intensity throughout the pancreas, indicating diffuse involvement. The ADCs of the pancreas and IgG4 index were significantly inversely correlated (Spearman's rank correlation coefficient, r (s) = -0.80, P < 0.05).

CONCLUSION:

Autoimmune pancreatitis showed high signal intensity on DWI, which improved after steroid treatment. ADCs reflected disease activity. Thus, diffusion-weighted MRI might be useful for diagnosing AIP, determining the affected area, and evaluating the effect of treatment.

• Authors: Takao Taniguchi, Hisato Kobayashi, Koji Nishikawa, Etsushi Iida, Yoshihiro Michigami, Emiko Morimoto, Rikiya Yamashita, Ken Miyagi, Motozumi Okamoto
• Journal: Japanese journal of radiology (Jpn J Radiol) Vol. 27 Issue 3 Pg. 138-42 (Apr 2009) ISSN: 1867-1071 [Print] Japan
• PMID: 19412681 (Publication Type: Journal Article)

Chemical References

• Immunoglobulin G
• Steroids

Topics

• Aged
• Autoimmune Diseases (diagnosis, drug therapy)
• Case-Control Studies
• Diffusion Magnetic Resonance Imaging (methods)
• Female
• Humans
• Immunoglobulin G (blood)
• Male
• Middle Aged
• Pancreatitis (diagnosis, drug therapy)
• Steroids (therapeutic use)
• Tomography, X-Ray Computed