Two-dimensional displacements (left panel) and PVD (right panel) for HD 37806, HD 45677, HD 58647, and HD 85567 as computed from the differential phase and described in Sect. 4.4. The data are colour-coded according to the radial velocity (scale on the right). In the 2D-displacement figures, the dashed lines show the best linear fit reported at the top of the panel. In the PVD panels, the blue and red shaded regions show the Keplerian rotation pattern (see text for more details).