High-resolution magnetic resonance cholangiography (MRC) with adaptive averaging: diagnostic performance evaluation

Aim: To evaluate the diagnostic performance of an interactive, adaptively averaged (AA) two-dimensional (2D) magnetic resonance cholangiography (MRC) technique in patients with suspected biliary disease by comparison to the standard MRC technique. Materials and methods: The AA 2D MRC method registers the images after acquisition, allowing summation of multiple images to improve the signal:noise ratio (SNR) and thereby potentially improve the visualization of bile ducts. One hundred and twenty-eight patients underwent both 2D conventional and AA magnetic resonance cholangiopancreatography (MRCP). Twenty-seven patients were excluded from the analysis as AA images could not be properly obtained due to technical failures. All examinations were performed using a 1.5 T whole-body MR system and a four-channel torso phased array coil. Images of 101 patients were adaptively averaged using an in-house developed program written in IDL. Two readers qualitatively evaluated the studies in consensus, blinded to acquisition details and without knowledge of clinical information. Results: The AA technique was significantly better than the conventional 2D MRC for the visualization of the second-order branch intrahepatic ducts (p < 00001). Overall, there was no significant difference in the diagnostic confidence between two techniques (p = 0.12). However, the AA technique showed a trend towards more confident diagnosis of biliary strictures (p = 0.055), likely due to better diagnostic confidence in identifying second order branch intrahepatic duct strictures (p = 0.054). Conclusion: Excluding those patients those patients in whom either satisfactory respiratory gating or a suitable kernel placement was not achieved, AA 2D MRC demonstrated a significant improvement in visualization of intrahepatic duct branches compared to standard MRC