Optimising time-varying gradient orientation for microstructure sensitivity in diffusion-weighted MR

► We investigate if varying the gradient waveform orientation improves axon radius estimates over having a fixed orientation. ► We found that varying orientation in perpendicular plane to the cylinders does not, but in a parallel one does. ► Similar improvement can be achieved by having one measurement in the parallel and the rest in a perpendicular direction. ► The results suggest that fixed orientation pulse sequences are the best choice for probing coherently oriented systems.