Time-Optimal VERSE for Multidimensional and Parallel Excitation

Daeho Lee¹, Michael Lustig¹, William Allyn Grissom¹, John Mark Pauly¹

Variable-rate selective excitation (VERSE) is a RF pulse reshaping technique. It is commonly used to reduce the peak magnitude and SAR of a RF pulse by reshaping RF and gradient waveforms to reduce RF magnitude while preserving the excitation profile. A general time-optimal VERSE algorithm for multidimensional and parallel excitation pulses is presented. This method is different from other VERSE techniques in that it provides a non-iterative time-optimal multidimensional solution, which drastically simplifies VERSE designs. Compared to other parallel excitation SAR-reduction strategies, the algorithm is trajectory-independent and allows the user to design pulses without enforcing RF constraints or making excitation error tradeoffs, and to subsequently obtain the shortest pulses possible that satisfy RF and gradient limits.