Investigation of annular pancreas through multiple detector spiral CT (MDCT) and MRI.

BACKGROUND AND PURPOSE: To investigate annular pancreas in adults using imaging features displayed on computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

Retrospective review of annular pancreas in patients undergoing CT or MRI examinations. Two abdominal radiologists blindly reviewed the CT, MRI, and magnetic resonance cholangiopancreatography (MRCP) images from the Picture Archiving and Communication Systems (PACS). A Kruskal-Wallis test was performed to evaluate subjective scoring, with Mann-Whitney test for the comparison. A p-value less than 0.05 was considered statistically significant.

RESULTS

Eleven patients (45.8%) presented a complete ring of pancreatic tissue surrounding duodenum, displayed as circular, triangular, or sandwich sign configuration, the other 13 patients (54.2%) had incomplete annular pancreas which displayed a crocodile jaw appearance, pancreatic tissue extending in a posterolateral or anterolateral direction towards duodenum. When comparing CT images of each sequence, the arterial phase group had the highest score compared with the venous phase and the plain film group (χ2  = 58.21, p < 0.05). When comparing MRI enhancement volumetric interpolated breath-hold examination (VIBE) sequences, arterial phase group scores were the highest (χ2  = 18.98, p < 0.05).

CONCLUSIONS

Both CT and MRI could detect annular pancreas, with artery phase being the best sequence to diagnose annular pancreas.