Study limitations
This study utilized a prospectively acquired single dataset of 3DE images in normal children, and therefore the findings need to be validated among cases with abnormal volumes, as agreement may diverge outside of the normal ranges. This was not a study on feasibility, and therefore we did not attempt to capture the number of children in which insufficient image quality could be obtained. We did not compare the two software directly to CMR which is considered the current reference standard, however, given TomTec 4D LV-analysis has been directly compared in previous large studies in measuring both LA and LV volumes and ejection/emptying fraction, we felt it was reasonable to use it as a reference6,7. We also acknowledge that 3DE has limitations related to the temporal resolution and spatial lateral resolution in the depth.