Focal pancreatitis mimicking pancreatic mass: magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) findings including diffusion-weighted MRI.
BACKGROUND
Focal pancreatitis (FP) is a confined inflammation that mimics a pancreatic mass. Its imaging diagnosis is important to avoid unnecessary procedures.


OBJECTIVE
To describe the spectrum of magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted MRI (DWI) findings of focal pancreatitis mimicking pancreatic masses.


METHODS
Findings of MRI/MRCP including DWI with a b value of 0 and 600 s/mm(2) in 14 patients with pancreatic masses on MRI were retrospectively reviewed and compared to normal pancreas in 14 patients as a control group.


RESULTS
FP revealed hypointense signal intensity (SI) (3/14), hypo- to isointense SI (7/14), or isointense SI (4/14) on T1-weighted images, and hypointense SI (1/14), isointense SI (5/14), iso- to hyperintense SI (7/14), or hyperintense SI (1/14) on T2-weighted images compared to remaining pancreas (RP). MRCP images revealed dilatation of the common bile duct (CBD) and main pancreatic duct (MPD) (5/14), dilatation of the MPD only (3/14), dilatation of the CBD only (3/14), and normal MPD and CBD (3/14). Both FP and RP revealed three types of time-signal intensity curves: 1) rapid rise to a peak, with a rapid decline (FP=2, RP=4), 2) slow rise to a peak, followed by a slow decline (FP=5, RP=4), and 3) slower rise to a peak, with a slow decline or plateau (FP=7, RP=6). Mean apparent diffusion coefficient (ADC) values for FP and RP were 2.09+/-0.18 and 2.03+/-0.2 x 10(-3) mm(2)/s, respectively. ADC values of FP and RP revealed no significant difference.


CONCLUSIONS
The spectrum of imaging findings of focal pancreatitis on MRI/MRCP including DWI was described. Findings of FP were not distinctive as compared to the remaining pancreas.
Department of Radiology, St. Louis University Hospitals, St. Louis, Missouri 63110, USA. ncbalci@gmail.com
A J
AJ
Momtahen
N C
NC
Balci
S
S
Alkaade
E I
EI
Akduman
F R
FR
Burton
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049448:Cholangiopancreatography, Magnetic Resonance / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010179:Pancreas / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010195:Pancreatitis / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies
D003287:Contrast Media; D019786:Gadolinium DTPA