Fig. 2

Possible effects on apparent strain of through-plane tissue displacements and trabecular appearances. Panel a This end-diastolic four chamber cine frame shows a basal septal bulge (*) whose long axis displacement causes it to move apically (arrow) to its end systolic position (b). Here it has moved into the short axis plane marked by the pale line. The septum in that short axis plane will therefore appear to have thickened more than it really did so that excess radial strain could be measured by tissue boundary tracking. Conversely, a more basal short axis slice might underestimate local radial strain due to tapering of the septum near the atrio-ventricular junction. Panel c Short axis images typically show trabeculations inside the LV free wall. Panel d this resin cast of human heart cavities shows the typical right handed helical alignments of free wall trabecular indentations. Systolic long axis displacement of these oblique trabecular structures (arrow) could give a false impression of trabecular displacement in the plane indicated by the white bar. A further issue is that trabeculations tend to thicken and move together in systole. This can exclude intervening blood, particularly in a hypertrophied ventricle with good function (panel e, from the same cine as c). If they merge to appear as part of the LV wall, it could result in over-estimation of radial and circumferential strain, if these were based on attempting to track the apparent endocardial boundary