Fig. 1

a Opening the 3D study, the system displays a four and a two chamber view where the observer has to manually set a total of four landmarks (orange dots) to indicate the mitral valve annulus in two perpendicular planes; b as a second step, the aortic valve has to be identified (red dot); c subsequently, a long axis view is displayed where the observer has to indicate the apical aortic annulus point (blue dot); d finally, the observer has to mark the mitral leaflets coaptation (yellow dot) in the same long axis view; e when all landmarks have been set, the program automatically tracks the mitral valve