Autoimmune pancreatitis: CT patterns and their changes after steroid treatment.
OBJECTIVE
To retrospectively evaluate the computed tomographic (CT) patterns of autoimmune pancreatitis (AIP) and their changes after steroid therapy.


METHODS
Investigational review board approval was obtained, and the informed consent requirement was waived. The medical and imaging data of 21 patients (13 men, eight women; mean age, 47.5 years; age range, 25-79 years) with histopathologically proved AIP who underwent contrast material-enhanced CT at diagnosis and after steroid treatment were included in this study. Image analysis included assessment of the (a) presence or absence and type (focal or diffuse) of pancreatic parenchyma enlargement, (b) contrast enhancement of pancreatic parenchyma, (c) size of the main pancreatic duct (MPD) within the lesion and upstream, and (d) pancreatic parenchyma thickness in the head, body, and tail of the pancreas. The same criteria were applied to follow-up CT examinations, the follow-up data were compared with pretreatment data, and a paired sample t test was applied.


RESULTS
Pancreatic parenchyma showed focal enlargement in 14 (67%) patients and diffuse enlargement in seven (33%). Pancreatic parenchyma affected by AIP appeared hypoattenuating in 19 (90%) patients and isoattenuating in two (10%). During the portal venous phase, pancreatic parenchyma showed contrast material retention in 18 (86%) patients and contrast material washout in three (14%). The MPD was never visible within the lesion. After treatment, there was a reduction in the size of pancreatic parenchyma segments affected by AIP (P < .05). Fifteen (71%) of the 21 patients had a normal enhancement pattern in the pancreatic parenchyma, whereas the enhancement pattern remained hypovascular in six (29%). The MPD returned to its normal size within the lesion in all patients at follow-up CT. In one of the eight patients with focal forms of AIP, the upstream MPD remained dilated.


CONCLUSIONS
AIP appeared as pancreatic parenchyma enlargement, with MPD stenosis within the lesion and upstream dilatation in focal forms of AIP. After steroid treatment, there was normalization of these findings.
Manfredi
Riccardo
R
Department of Radiology, University of Verona, Verona, Italy. riccardo.manfredi@univr.it
Graziani
Rossella
R
Cicero
Calogero
C
Frulloni
Luca
L
Carbognin
Giovanni
G
Mantovani
William
W
Mucelli
Roberto Pozzi
RP
D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D003287:Contrast Media; D003974:Diatrizoate Meglumine; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D010195:Pancreatitis / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D011241:Prednisone / Q000627:therapeutic use; D011857:Radiographic Image Interpretation, Computer-Assisted; D012307:Risk Factors; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
D003287:Contrast Media; D005938:Glucocorticoids; D003974:Diatrizoate Meglumine; D007472:Iohexol; C038192:iopromide; D011241:Prednisone