Optimisation of pulse-specific phase schedule reduces peak RF amplitude in multiband parallel-transmit pulses

Multiband(MB) imaging can greatly reduce scan time, but MB pulses often encounter peak amplitude constraints. An optimal phase schedule has been published for traditional single-transmit (sTx) RF pulses. However, after an initial evaluation, we found that it only has marginal benefits for parallel-transmit (pTx) pulses. We compared four common optimisation algorithms (fmincon, fminsearch, simmulated annealing, global search) to determine the most suitable algorithm for choosing the best offset phases for a pTx pulse. Overall, fmincon efficiently selected the optimal phase schedule of a pTx pulse and lowered peak amplitude by an average of 15% when MB-factor=3.