The cardiac magnetic resonance short-axis images provide examples of the pre-contrast and post-contrast contours required to calculate iECV. Systolic and diastolic contours are drawn using the short-axis stack to calculate myocardial volume, which is necessary to derive iECV. Color look-up tables have not been applied to the T1 images. iECV provides a surrogate of the total myocardial fibrosis burden according to the formula demonstrated in the figure. iECV demonstrates good correlation with histological fibrosis burden and severity of aortic stenosis. Graph adapted from Chin et al. (41), Creative Commons Attribution License: https://creativecommons.org/licenses/by/4.0/. BSA = body surface area; other abbreviations as in Figure 2.