FIGURE 7.  Illustration of difference between stacked slices and true 3D calculation of MCA. In stacked slices' analysis, the MCA (MCA_slices) is calculated as the length of the midmyocardial contour on 2D images, as illustrated on left-hand side, multiplied by slice thickness (d). As illustrated on right-hand side, 3D calculation of MCA (MCA_3D) of LV locally differs from MCA_slices depending on myocardial curvature perpendicular to slice orientation. The relationship between d and the real extension of the midmyocardial contour in the through-plane direction (L) depends on the angle () enclosed by the through-plane curvature and the sectioned slice. Midventricular contour is approximated by a piecewise linear line to demonstrate this effect.