Figure 3
From: Myocardial tissue tagging with cardiovascular magnetic resonance
Schematic diagram demonstrating the three dimensional circumferential - radial - longitudinal (RCL) coordinate system used for strain calculation. Normal strains (dark solid arrows) are described with respect to the short axis plane: E CC represents circumferential shortening tangential to epicardial surface, E RR represents myocardial thickening radially towards the center of the ventricle and E LL represents basal to apical shortening along the ventricular long axis.E RC , E RL and E CL (dotted and curved arrows) represent change in angle caused by shear. Torsion represents the wringing motion caused by an apical counterclockwise rotation (curved arrow A) and a basal clockwise rotation (curved arrow B) around the ventricular long axis at end systole. Torsional deformation compensates for the opposing vectors in the subepicardium and subendocardium created by opposing myofiber arrangement in both layers.