Figure 11.

Phantom signal intensity (S) from experiment and calculated steady-state $B_1^{+}-\text{dependent}$ factor (F in Eq. 7b) values for the cases of second-order static field shimming (first row) and no static field shimming (second row). Static field maps are shown in column 1, and S and F maps for the three pulse types are indicated at the top of the other columns. When static field shimming is active, the BIR-4 and optimized composite pulses result in significant improvement in flip-angle uniformity as compared to the block pulse. When no static field shimming is present (and B₀ variations are similar in range to that of the human brain at 7T), the BIR-4 pulse results in much reduced flip-angle uniformity while optimized pulse performance is similar to the case when static field shimming is applied. The dashed vertical line in the first image indicates the position of the line profiles plotted in Fig. 12.