Purpose: To compare and evaluate images of non-contrast-enhanced MR portography acquired with two different methods, the flow-in and flow-out methods.
Materials and Methods: Twenty-five healthy volunteers were examined using respiratory-triggered three-dimensional balanced steady-state free-precession (SSFP) with two selective inversion recovery pulses (flow-in method) and one tagging pulse and one nonselective inversion recovery pulse (flow-out method). For quantitative analysis, vessel-to-liver contrast (Cv-l) ratios of the main portal vein (MPV), right portal vein (RPV), and left portal vein (LPV) were measured. The quality of portal vein visualization was scored using a four-point scale.
Results: The Cv-ls of the MPV, RPV, and LPV were all significantly higher with the flow-out than flow-in method (MPV = 0.834 +/- 0.06 versus 0.711 +/- 0.10; RPV = 0.861 +/- 0.04 versus 0.729 +/- 0.11; LPV = 0.786 +/- 0.08 versus 0.545 +/- 0.22; P < 0.0001). In all analyses of vessel visibility, non-contrast-enhanced MR portography with the flow-out method showed higher scores than with the flow-in method. With the flow-out method, visual scores of the MPV, RPV, portal vein branches of segments 4 (P4), and 8 (P8) were significantly better than with the flow-in method (MPV = 3.4 +/- 0.7 versus 2.6 +/- 0.9; RPV = 4.0 +/- 0.0 versus 3.5 +/- 0.9; P4 = 2.8 +/- 1.3 versus 1.6 +/- 1.0; P8 = 4.0 +/- 0.0 versus 2.9 +/- 1.1; P < 0.05).
Conclusion: Non-contrast-enhanced MR portography with the flow-out method improves the visualization of the intrahepatic portal vein in comparison with the flow-in method.