Fig. 2. Comparison of multiple excitation scenarios. Patient centric coordinate system with origin at heart. Simulations of Ella are only available in the light gray area. A) Amplitude limit of all simulations. B) Maximum normalized SAR in each group for cases of Fig. 1B. C) Overlay of the voxel models. D) Ratio between optimized mean(B₁⁺) of image slice (i.e. excitations of same or better homogeneity than CP mode) and mean(B₁⁺) of CP reference mode. E) same as D) but multiplied with safety factor obtained from the respective (i->j) maximum normalized SAR (CP reference mode unchanged).

Fig. 4. A) Sweep analysis of SAR-limit (SL, black) and amplitude limit (AL, blue) of human voxel model Duke in center position using interpolation from two anchor simulations shifted by ∆z=±50 mm (cf. Fig. 3). 10000 random excitation vectors are scaled to satisfy the anchor limits. A maximum normalized SAR > 1 (red) is unsafe, a normalized SAR < 1 (gray) wastes B₁⁺ performance. AL is more conservative than SL. B) Corresponding curves if extrapolation from only one anchor simulation at ∆z=+50 mm is used.