FIG. 2.

Impacts of RF array designs on excitation performance when designing pulses to excite axial (a), coronal (b), sagittal (c) or oblique (d) slices. L-curves quantifying the tradeoff between peak 10g SAR and root mean square excitation error (RMSE) are shown. For all cases, pTx MB pulses were designed for an MB factor of 2 (MB2) and with peak 10g SAR control. All local SAR numbers were calculated assuming single shot EPI image acquisitions with slice thickness=6 mm, pulse duration=1 ms, nominal flip angle=10 degrees and TR=1 s. Note that for each slice direction, the double-ring 2×8 array consistently outperformed the other two conventional single-ring arrays.