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.