Efficacy of non-breath-hold magnetic resonance cholangiography at midfield strength

The efficacy of non-breath-hold magnetic resonance (MR) cholangiography at mid-field strength (0.5 Tesla) was evaluated for delineating biliary anatomy and the cause and extent of biliary obstruction. We performed 65 MR cholangiograms on a mid-held 0.5 Tesla MR unit and correlated them with contrast cholangiography and/or surgery. MR cholangiography was found to be both sensitive and specific in the detection of biliary obstruction and in the definition of its cause (sensitivity 98%, specificity 100%, positive predictive value 100%, negative predictive value 85.7%, accuracy 98%), MR cholangiography accurately predicted the level of obstruction in 94 per cent of strictures. Normal caliber intra-hepatic biliary radicles were visualised in only 6 percent of the MR cholangiograms. In contrast, 94 per cent of dilated intrahepatic. biliary radicles were demonstrated. The confluence, and right and left hepatic ducts were visualized in 98 percent; the gall bladder in 65 percent; the cystic duct in 45 percent and the cystic duct insertion in 25 per cent. The extrahepatic bile duct was seen In 82.7 percent. A normal caliber pancreatic duct was seen in 18 percent while a dilated pancreatic duct was seen in 86 percent. The pancreatico-biliary junction was visualised in 7 percent. Non-breath-hold MR cholangiography at mid-field strength is a highly accurate method of evaluating the cause and level of biliary obstruction, comparable to high-field MR cholangiography. The spatial resolution however is inadequate for the detection of variations in biliary or pancreatic ductal anatomy when the ducts are of normal caliber.