Anatomic variants of the biliary tree: Diagnosis with MR cholangiopancreatography

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) cholangiopancreatography in the diagnosis of anatomic variants of the biliary tree. MATERIALS AND METHODS: In 171 patients, the anatomy of the biliary tree was evaluated with MR cholangiopancreatography. Two independent reviewers evaluated the presence of anatomic variants. Contrast material-enhanced cholangiography that was previously performed opacified the cystic duct in 77 patients and the bile duet bifurcation in 93 patients, and was chosen as the standard of reference in the diagnosis of anatomic variants. RESULTS: MR cholangiopancreatography demonstrated the cystic duct in 126 patients (74%). MR cholangiopancreatography showed a low cystic duct insertion in 11 patients (9%), a medial cystic duct insertion in 22 patients (17%), and a parallel course of the cystic and hepatic ducts in 31 patients (25%). The bile duct bifurcation was demonstrated in 139 patients (81%), and an aberrant right hepatic duct was demonstrated in 12 patients (9%). CONCLUSION: MR cholangiopancreatography is accurate in the diagnosis of anatomic variants of the biliary tree that may increase the risk of bile duct injury during laparoscopic cholecystectomy.