An example of LV surface detection at ED using 4DLVQ is shown in (a). The standard apical views (top left, top middle, bottom left) were obtained by manual alignment. Each small circle in the apical views indicates a manually defined landmark used for initialization of surface detection. One SAX view (middle, bottom) was dynamically updated to reflect the trackball position, in order to facilitate precise landmark positioning and verification of the 3D surface detection. If necessary, additional landmarks could be added to leave papillary muscles within measured cavity volume. Three extra SAX views distributed between apex and base (right) were used to further verify the detected surface. The complete 4D surface detection at ES with time-volume curve is shown in (b).