Fig. 3
4D flow CMR and 2D PC CMR of the flow phantom at different flow rates. Preset flow rates were increased from 0.8 to 2.8Ā l/min (left to right). Comparative flow measurements were performed using velocity encoding both at 1Ā m/s (upper rows) and at 2Ā m/s (lower rows). Velocity-coded 4D flow CMR show velocity distribution in the portal system and TIPS stent graft. Color-coded pathlines demonstrate increasing flow velocities with increase of the preset flow rates. Measurement planes indicate the mid of the TIPS stent graft and correspond to the cross-sectional phase-contrast images shown for both 4D flow CMR (upper right corners) and 2D PC CMR (lower rows). Note that aliasing (arrows) occurred at higher flow rates and velocities when velocity encoding was set at 1Ā m/s. Aliasing was absent for all flow rates when velocity encoding set at 2Ā m/s