Figure 2: A correct (red) and wrong (cyan) registration result. In both cases, the contrasted area is fully inside the projection shadow represented by the colored outlines. Both registration results lead to a similar NCC value when using an area-based feature for automatic registration. Note that motion artifacts could be kept to a minimum thanks to the best reference frame selection. Only some residual artifacts remained in the vicinity of the moving coronary sinus (CS) catheter and the diaphragm; see white arrows.