Magnetic resonance imaging and diseases of the liver and biliary tract. Part 2. Magnetic resonance cholangiography and angiography and conclusions

Magnetic resonance cholangiography (MRC) relies on the strong T-2 signal fr om stationary liquids, in this case bile, to generate images. No contrast a gents are required, and the failure rate and risk of serious complications is lower than with endoscopic retrograde cholangiopancreatography (ERCP). D ata from MRC can be summated to produce an image much like the cholangiogra m obtained by using ERCP. In addition, MRC and conventional MRI can provide information about the biliary and other anatomy above and below a biliary obstruction. This provides information for therapeutic intervention that is probably most useful for hilar and intrahepatic biliary obstruction. Magne tic resonance cholangiography appears to be similar to ERCP with respect to sensitivity and specificity in detecting lesions causing biliary obstructi on, and in the diagnosis of choledocholithiasis. It is also suited to the a ssessment of biliary anatomy (including the assessment of surgical bile-duc t injuries) and intrahepatic biliary pathology. However, ERCP can be therap eutic as well as diagnostic, and MRC should be limited to situations where intervention is unlikely, where intrahepatic or hilar pathology is suspecte d, to delineate the biliary anatomy prior to other interventions, or after failed or inadequate ERCP. Magnetic resonance angiography (MRA) relies on t he properties of flowing liquids to generate images. It is particularly sui ted to assessment of the hepatic vasculature and appears as good as convent ional angiography. It has been shown to be useful in delineating vascular a natomy prior to liver transplantation or insertion of a transjugular intrah epatic portasystemic shunt. Magnetic resonance angiography may also be usef ul in predicting subsequent variceal haemorrhage in patients with oesophage al varices. (C) 2000 Blackwell Science Asia Pty Ltd.