Trajectory Optimization for Variable-Density Spiral Two-Dimensional Excitation
Pauly J, Spielman D, Pisani L, Levin Y
Stanford University School of Engineering
This work proposes a simple method to optimize the excitation k-space trajectory for variable density (VD) spiral excitation. Spiral trajectories are approximated as concentric circles, and the Hankel transform is used to compute the resulting slice profile. The circle approximation is validated by comparison to slice profiles resulting from actual spiral trajectories. Using a polynomial to describe placement of the circles (and therefore density), a 1 cm inversion pulse is designed to minimize the height of peak sidelobes. Peak sidelobe height is reduced by 80% compared to uniform density excitation.