Fig. 1

The velocity offset correction shown in a case of pulmonary artery (PA) flow assessment: original velocity map with the PA in cross-section (arrow) (a), mask of stationary pixels (b), 3D graph with fitted first order plane (in black) to the velocity values in the mask (blue points) showing the variation in background offset over the field of view (c) (see text) and corrected velocity map (d). Visually the corrected map shows that the left to right gradient in offset has been removed. (These images are shown with a small zoom which is why no PE FOV wraparound is seen)