Fast joint design method for parallel excitation radiofrequency pulse and gradient waveforms considering off-resonance.

A fast parallel excitation pulse design algorithm to select and to order phase-encoding (PE) locations (also known as "spokes") of an Echo-Volumar excitation k-space trajectory considering B(0) field inhomogeneity is presented. Recently, other groups have conducted research to choose optimal PE locations, but the potential benefit of considering B(0) field inhomogeneity during PE location selection or their ordering has not been fully investigated. This article introduces a novel fast greedy algorithm to determine PE locations and their order that takes into account the off-resonance effects. Computer simulations of the proposed algorithm for B(1) field inhomogeneity correction demonstrate that it not only improves excitation accuracy but also provides an effective ordering of the PE locations.