Comparison of workflow for 4DLVQ (a) and TomTec (b). With 4DLVQ, each view is aligned to the standard apical view. Initialization is done at ED using 3 clicks in each apical view. 3D surface detection is automatically triggered, and if necessary the detected 3D surface is edited manually by adding landmarks. This is an interactive procedure where the 3D surface detection is repeated after each new landmark. Once completed with ED, the same procedure is repeated for ES. When both ED and ES are finished, a full 4D surface detection is performed to obtain EDV, ESV, and EF along with a time-volume curve. At this stage it is possible to edit the surfaces if improvements are required. With TomTec, initialization is done by accurate tracing at both ED and ES in each view after alignment to the standard apical views. 4D surface detection is done directly after initialization, and correction is done to the resulting surfaces if required.