William A. Grissom1, Adam B. Kerr, Pascal P.
Stang2, Greig C. Scott2, Ileana Hancu3, Mika
W. Vogel4, John M. Pauly2
1Electrical Engineering and Radiology,
Stanford University, Stanford, CA, United States; 2Electrical
Engineering, Stanford University, Stanford, CA, United States; 3GE
Global Research, Niskayuna, NY, United States; 4Advanced Medical
Applications Laboratory, GE Global Research, Munich, Bavaria, Germany
We
introduce a new framework for optimizing the phase encoding locations of a 2D
or 3D parallel excitation pulse in the large-tip-angle regime. The framework
is analogous to the hard pulse approximation, and yields a straightforward
analytical relationship between the pulses' spin-domain rotations and the
phase encoding locations. This relationship can be exploited to optimize
locations using gradient descent, or using optimization transfer for
monotonic, parameter-free optimization. We apply our method to the design of
dual-band (fat + water) spin echo parallel excitation pulses along 3D rungs
trajectories.