VERSE-Guided Numerical RF Pulse Design

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

Numerical optimization-based RF pulse design methods are widely used to incorporate system non-idealities and non-linearities such as field inhomogeneities, coil sensitivities, and signal decay. These approaches often lead to RF pulses with high peak RF magnitude exceeding the hardware or safety limits and the variable-rate selective excitation (VERSE) principle can be utilized to directly constrain the peak RF power on-the-fly. However, discrete-time implementations of VERSE may not preserve spins' rotational behavior due to the imperfect system modeling and sampling. Also, the excitation profile of reshaped pulses is affected by time-dependencies that are not accounted for in VERSE. To effectively correct these errors while achieving a fast peak RF power control, VERSE-guided numerical RF pulse design framework is introduced for parallel transmit applications.