Evaluation of aberrant bile ducts before laparoscopic cholecystectomy: helical CT cholangiography versus MR cholangiography.

OBJECTIVE: The purpose of our study was to compare the accuracy of helical CT cholangiography and that of MR cholangiography in the diagnosis of aberrant bile ducts or cystic ducts before laparoscopic cholecystectomy. SUBJECTS AND METHODS: A total of 120 consecutive patients, including 114 patients with cholecystolithiasis and six with gallbladder polyps, were treated using laparoscopic cholecystectomy between November 1996 and August 1998. Eighteen (15%) of the 120 patients were suspected of having aberrant bile ducts or cystic ducts on helical CT cholangiography, and 16 of these 18 patients were subsequently examined on MR cholangiography. For the 16 patients who underwent both imaging examinations, findings from helical CT cholangiography and MR cholangiography were compared with intraoperative cholangiography.
RESULTS: Aberrant bile ducts in 13 patients and aberrant cystic ducts in three patients were divided into six types on the basis of the results of intraoperative cholangiography. Although these types were clearly identified using helical CT cholangiography in all 16 patients, the anatomic variants were not correctly identified in seven (44%) of the 16 patients with MR cholangiography. False-negative findings were mainly a result of the insertion sites of the cystic ducts or aberrant bile ducts being obscured by aberrant bile ducts or duodenum. Two (2%) of the 120 patients developed mild adverse reactions to the contrast material, but neither required treatment.
CONCLUSION: Helical CT cholangiography clearly showed aberrant bile ducts and cystic ducts, but visualization of these structures on MR cholangiography was unsatisfactory because of overlapping duodenum and hepatic ducts.