Dual-phase CT of autoimmune pancreatitis: a multireader study.
OBJECTIVE
The purpose of this study was to identify findings that aid in differentiating autoimmune pancreatitis from pancreatic carcinoma using dual-phase CT.


METHODS
Dual-phase CT scans of 74 patients (25 with autoimmune pancreatitis, 33 with pancreatic carcinoma, and 16 with a normal pancreas) were independently evaluated by three radiologists for enhancement of the pancreas; the presence of a capsule-like rim, peripancreatic strands, and pancreatic calcifications; pancreatic duct or bile duct changes; and renal involvement. The frequency of CT characteristics was compared between autoimmune pancreatitis and carcinoma. Interobserver agreement for the three reviewers for the assessment of CT characteristics was evaluated using kappa statistics.


RESULTS
Diffusely decreased enhancement of the pancreas (autoimmune pancreatitis vs carcinoma: 28% vs 3%; p = 0.02, kappa = 0.33-0.75), capsule-like rim (40% vs 9%; p = 0.009, kappa = 0.42-0.66), peripancreatic strands (60% vs 27%; p = 0.02, kappa = 0.45-0.54), pancreatic calcifications (32% vs 9%; p = 0.04, kappa = 0.14-0.47), bile duct wall enhancement (52% vs 6%; p = 0.0001, kappa = 0.28-0.47), and renal involvement (28% vs 0%; p = 0.002, kappa = 0.32-0.74) were more frequent in patients with autoimmune pancreatitis. Pancreatic duct dilation (24% vs 67%; p = 0.001, kappa = 0.65-0.73) and abrupt cutoff (16% vs 55%; p = 0.003, kappa = 0.60-0.65) were more frequent in patients with carcinoma.


CONCLUSIONS
Diffusely decreased enhancement of the pancreas, a capsule-like rim, bile duct enhancement, and renal involvement are useful signs of autoimmune pancreatitis.
Takahashi
Naoki
N
Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
Fletcher
Joel G
JG
Fidler
Jeff L
JL
Hough
David M
DM
Kawashima
Akira
A
Chari
Suresh T
ST
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging*; D002277:Carcinoma / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010179:Pancreas / Q000000981:diagnostic imaging*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D010195:Pancreatitis / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*