Isotropic resolution in Diffusion Weighted Imaging using 3D multi-slab, multi-echo Echo Planar Imaging

INTRODUCTION Diffusion weighted Magnetic Resonance Imaging (DWI) is usually performed using a 2D single shot echo planar imaging technique, because it generates good SNR, short scan times and is immune to phase differences between diffusion-encoded excitations. 2D DWEPI can be acquired with a reasonably high in-plane resolution, especially if parallel imaging is used to reduce the geometric distortions. However, due to non-square RF-pulse profiles and slice cross-talk (especially for thin slices), banding artifacts occurs in the slice direction. These are easily seen when reformatting axial 2D images in for example the sagittal plane. Striving for isotropic resolution, such as often the case in fiber tractography, a 3D technique may therefore be preferred. In this work we propose a new readout strategy that is combined with a 3D multi-slab encoding, with the purpose of achieve sharp and thin slice profiles [1]. Furthermore, we propose a strategy to correct phase differences between diffusion encoded excitations and non-square slab profiles.