Use of magnetic resonance cholangiography in the diagnosis of choledocholithiasis: prospective comparison with a reference imaging method.

BACKGROUND Magnetic resonance cholangiography (MRC) is a new technique for non-invasive imaging of the biliary tract. AIM To assess the results of MRC in patients with suspected bile duct stones as compared with those obtained with reference imaging methods. PATIENTS/METHODS 70 patients (34 men and 36 women, mean (SD) age 71 (15.5) years; median 75) with suspected bile duct stones were included (cholangitis, 33; pancreatitis, three; suspected post-cholecystectomy choledocholithiasis, nine; cholestasis, six; stones suspected on ultrasound or computed tomography scan, 19). MR cholangiograms with two dimensional turbo spin echo sequences were acquired. Endoscopic retrograde cholangiography with or without sphincterotomy (n = 63), endosonography (n = 5), or intraoperative cholangiography (n = 2) were the reference imaging techniques used for the study and were performed within 12 hours of MRC. Radiologists were blinded to the results of endoscopic retrograde cholangiography and previous investigations. RESULTS 49 patients (70%) had bile duct stones on reference imaging (common bile duct, 44, six of which impacted in the papilla; intrahepatic, four; cystic duct stump, one). Stone size ranged from 1 to 20 mm (mean 6.1, median 5.5). Twenty seven patients (55%) had bile duct stones smaller than 6 mm. MRC diagnostic accuracy for bile duct lithiasis was: sensitivity, 57.1%; specificity, 100%; positive predictive value, 100%; negative predictive value, 50%. CONCLUSIONS Stones smaller than 6 mm are still often missed by MRC when standard equipment is used. The general introduction of new technical improvements is needed before this method can be considered reliable for the diagnosis of bile duct stones.