Biliary ascariasis: CT, MR cholangiopancreatography, and navigator endoscopic appearance--report of a case of acute biliary obstruction.

A case of acute common bile duct obstruction caused by a roundworm in a 6-year-old girl is reported. Computed tomography (CT) and magnetic resonance imaging (MRI) showed "bull's-eye" and "eye-glass" appearances of the ascaris in the common bile duct. On reformation of the transverse CT and coronal MR images, the tubular Ascaris was better depicted. MRI and navigator endoscopic demonstrations of the common bile duct ascaris have not been described previously in the literature. These CT and MRI findings may be helpful in the diagnosis of Ascaris.