Prospective assessment of magnetic resonance cholangiopancreatography for noninvasive imaging of the biliary tree.

BACKGROUND: Traditionally, ERCP has been the only reliable method for imaging the biliary tree, but it is invasive and carries a risk of complications. Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive method for imaging the biliary tree. The aim of this study was to prospectively assess the accuracy of MRCP in a large number of patients.

METHODS: Consecutive patients referred to a teaching hospital for ERCP were eligible for study entry. MRCP was performed within 24 hours before ERCP. MRCP findings were compared with ERCP findings or, when the initial ERCP was unsuccessful, with results of repeat ERCP, percutaneous transhepatic cholangiography, or surgery.

RESULTS: One hundred forty-six patients underwent 149 ERCP/MRCP procedures, of which 129 were evaluable with successful MRCP and ERCP or an ERCP-equivalent study. Diagnoses included choledocholithiasis in 46 and biliary stricture in 12 patients. The sensitivity, specificity, positive, and negative predictive values for MRCP in the diagnosis of choledocholithiasis were 97.9%, 89.0%, 83.6%, and 98.6%, respectively. All 12 strictures were diagnosed by MRCP (sensitivity 100%, specificity 99.1%).

CONCLUSIONS: MRCP is an accurate, noninvasive alternative to ERCP for imaging the biliary tree. Choledocholithiasis and biliary strictures can be reliably diagnosed or excluded by MRCP. MRCP should be used increasingly in patients with suspected biliary obstruction to select those who require a therapeutic procedure.