An Efficiency Metric for K-Space Trajectories

Christopher J. Hardy¹, Luca Marinelli¹

To maximize speed, k-space trajectories should be designed to allow efficient traversal under conditions of constrained gradient amplitude and slew rate. We employ a rate remapping algorithm to always push gradient amplitude or slew rate to the limit over the whole course of the trajectory, creating time-optimal gradient waveforms. Given constant extent of 2D k-space coverage, the average density of coverage is assumed to be proportional to the total length of the trajectory. Trajectory length divided by the time of traversal can then be taken as an efficiency metric. Various trajectories are compared using this metric.