Integrated analysis of autoimmune pancreatitis by CT, MRCP and DWI

Abstract

PurposeCT, MRCP and diffusion weighted imaging characteristics were discussed to improve the diagnostic accuracy of autoimmune pancreatitis. Materials and methods23 cases of confirmed autoimmune pancreatitis were retrospectively analyzed before treatments. 23 cases underwent CT unenhanced and enhanced scans, 21 cases underwent MRCP examination, and 11 cases underwent DWI examination. Pancreatic lesion, involvement of the pancreatic duct and bile duct, changes of adjacent artery and vein, and other organs lesions. CT values and ADC values of pancreas and lesion were measured. ResultsFocal type lesions were shown in 6 cases, diffuse type in14 cases, and both types in 3 cases. Diffuse pancreatic swelling was shown in 20 cases, and peripancreatic halo in 13 cases. Mean CT values of lesions: unenhanced scan 35.81 ± 6.23 HU, late arterial phase 75.80 ± 17.47 HU, venous phase 93.19 ± 14.06 HU, and equilibrium phase 90.00 ± 14.67HU. Delayed homogenous enhancement was shown in 17 cases. Tapered narrowing (12 cases) or multiple segmental pancreatic duct stenosis (8 cases) was detected, the absence of main pancreatic duct dilatation or less than 3.5 mm in 20 cases, and duct penetrating sign in 20 cases. Bile duct lesions were found in 20 cases. ADC values of lesions (0.99 ± 0.03 × 103 mm2/s) were significantly lower that of pancreas (1.47 ± 0.16 × 103 mm2/s). ConclusionCT and MRI integrated diagnosis was helpful for accurate diagnosis based on the distinctive imaging characteristics of autoimmune pancreatitis.