Bland-Altman-Plot for assessment of ejection fraction. (a) Reader 1 (R1): summation of slices (SoS) versus guide-point modeling (GPM) method. (b) Reader 2 (R2): SoS versus GPM approach. (c) Interobserver comparison of the SoS method based on a stack of short axis views. (d) Multi-orientation highly accelerated sequences analyzed with the GPM approach: R1 versus R2.