On the Application of Phase Correction and Use of K-Space Entropy in Partial Fourier Diffusion-Weighted EPI

Samantha J. Holdsworth¹, Stefan Skare¹, Roland Bammer¹

It is well-known that diffusion-weighted (DW) imaging is very sensitive to the effects of brain motion, even in single-shot (ss)-EPI. Pulsatile brain motion that occurs during the application of the DW gradients can result in the non-linear dispersion of k-space, corresponding to signal dropout and shading in the image domain. Here we explore the use of k-space entropy as a metric to identify k-space corrupted by non-linear brain motion; the use of peripheral cardiac gating and non-gating; phase correction applied before both homodyne and POCS reconstruction; as well as the number of overscans that should be used to avoid significant artifacts due to pulsatile brain motion.