Management of suspected biliary disease requires accurate evaluation for biliary obstruction. Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for evaluation of the biliary tract, but post-test pancreatitis and even death are possible. Magnetic resonance cholangiopancreatography (MRCP) provides clear visualization of the biliary and pancreatic ducts. Contrast agents are not needed because stagnant fluids have high-signal intensity and contrast distinctively with nearby solid tissue and fast-moving fluids such as blood. Magnetic resonance imaging (MRI) done at the same time can add information about malignant disorders. Because ERCP may be necessary after MRCP, Romagnuolo and associates reviewed the utility of MRCP in suspected biliary disease.
The authors performed a meta-analysis of studies comparing MRCP with other diagnostic modalities in a variety of disease states. Among the 67 articles included, the imaging end points used were presence of obstruction (30 studies with 1,954 patients), level of obstruction (eight studies with 572 patients), presence of biliary lithiasis (46 studies with 3,592 patients), and presence of malignancy (22 studies with 1,294 patients).
The overall adjusted sensitivity and specificity were 95 and 94 percent, respectively. The results for each end point were high, although sensitivity was slightly lower for the diagnosis of stones and differentiation of benign from malignant biliary obstructions.
The authors conclude that MRCP is highly accurate in the detection of biliary tract obstruction but less accurate in distinguishing benign from malignant lesions causing obstruction. Choledocholithiasis is accurately identified, but small stones in normal ducts may not be visualized. Further studies will help clarify which patients will benefit most from MRCP.