Biliary Anatomy on 3D MRCP: Comparison of Volume-Rendering and Maximum-Intensity-Projection Algorithms

Purpose: To compare Volume-rendering (VR) and maximum-intensity-projection (MIP) of three-dimensional T2-weighted turbo spin-echo magnetic resonance cholangio-pancreatography using a free-breathing navigator-triggered prospective acquisition correction (3D-TSE-PACE-MRCP) to define biliary anatomies. Materials and Methods: VR and MIP images of 3D-TSE-PACE-MRCP for 102 patients were retrospectively evaluated. Interpretation of cystic duct variation and biliary branching patterns of each image were recorded independently by two radiologists in a blinded fashion. Interpretation confidence on a five-point scale was compared using the Wilcoxon signed-rank test. The McNemar test was use to compare the accuracies of each reformation with the reference standard obtained by consensus interpretation of both the images and source images. Results: The reference standard identified all biliary bifurcations and 95 of 102 cystic duct confluences (93. 1%). VR findings agreed with the reference standard findings more often than MIP with regard to cystic duct variation (94 [92.2%] vs. 76 [74.5%], P < 0.01) while there was no significant difference for biliary branching patterns (99 [97. 1%] vs. 92 [90.2%], P = 0.092). The mean confidence score was significantly higher with VR than MIP with regard to both cystic duct variation and biliary branching patterns (3.7 vs. 2.4; P < 0.01; 4.1 vs. 3.3: P < 0.01). Conclusion: VR reformation of 3D-TSE-PACE-MRCP defines biliary anatomies more accurately than MIP.