The diagnostic accuracy of magnetic resonance cholangiopancreatography and ultrasound compared with direct cholangiography in the detection of choledocholithiasis.

AIM: To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) and ultrasound (US) in the diagnosis of choledocholithiasis in a large group of patients with bile duct stones confirmed at direct cholangiography. Also, to compare bile duct stones confirmed at direct cholangiography. Also, to compare bile duct stone characteristics using the three different investigations, endoscopic retrograde cholangiopancreatography (ERCP), MRCP and US.

MATERIALS AND METHODS: 191 patients (M:F, 76:115; mean age, 66 years; range, 24-92 years) were investigated by direct cholangiography, MRCP and US. Their final diagnosis as determined at direct cholangiography were choledocholithiasis (n = 34), strictures (n = 47) and normal ducts (n = 110). The direct cholangiographic methods used for diagnosis of choledocholithiasis were ERCP (n = 29), intraoperative cholangiography (n = 3) and percutaneous transhepatic cholangiography (n = 2). The bile duct stone characteristics were compared using ERCP, MRCP and US in the 29 patients in whom stones were exclusively diagnosed by ERCP.

RESULTS: Compared with the final diagnosis, MRCP had a sensitivity, specificity and diagnostic accuracy of 91%, 98% and 97%, respectively, in the diagnosis of choledocholithiasis. MRCP resulted in three false-negative and three false-positive findings, four of which occurred due to confusion with lesions at the ampulla. US had a sensitivity, specificity and diagnostic accuracy of 38%, 100% and 89%, respectively, in the diagnosis of choledocholithiasis. ERCP diagnosed more stones and the stones were more proximally distributed within the bile duct at ERCP when compared with MRCP.

CONCLUSION: MRCP has a high diagnostic accuracy (97%), similar to that at direct cholangiography, in the diagnosis of choloedocholithiasis. It has the potential to replace diagnostic ERCP and select patients with choledocholithiasis for therapeutic ERCP.