Daeho Lee1, William Allyn Grissom1,
Michael Lustig1, John Mark Pauly1
1Electrical Engineering, Stanford
University, Stanford, CA, United States
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.