BACKGROUND:Magnetic resonance cholangiography (MRC) is a non-invasive method for imaging biliary ducts. When used to exclude common bile duct (CBD) stones, MRC may obviate the need for intra-operative cholangiography (IOC). In this prospective study, MRC and IOC were compared for the diagnosis of suspected stones of the CBD. METHODS:Thirty patients with gallstones and suspected CBD lithiasis (abnormal serum liver tests and CBD>7 mm on ultrasound) had MRC followed by open cholecystectomy and IOC. MR imaging was done using a 1.5-T whole body scanner (Signa, General Electric Medical Systems). A torso phased-array coil with a 4-channel receiver was used for data acquisition. RESULTS:Over a period of 18 months, 30 patients (average age 53.9±13.3 years; range 38-76 years) were enrolled in this study. Eleven patients were male (36.7%) and 19 female (63.3%). MRC revealed CBD stones in 19 patients, while IOC revealed CBD stones in 22. The sensitivity of MRC in detecting CBD stones was 81.8%, and the speciifcity was 87.5%. The positive predictive value was 94.7%, and the negative predictive value was 63.3%. CONCLUSIONS:Pre-operative MRC may obviate the need for IOC. MRC reduces operative time, is less invasive, and may also alleviate damage to the CBD that can occurduring IOC. MRC can identify CBD stones pre-operatively and can help surgeons plan safe procedures. Pre-operative MRC should be done routinely in patients whose clinical or biochemical ifndings suggest the possibility of CBD stones.