Impact of the Point-Spread Function on Parameters Derived from Diffusion-Weighted Imaging: Axial Versus Sagittal Acquisition

J-Donald Tournier^1,2, Fernando Calamante^1,2, Alan Connelly^1,2

Diffusion-weighted imaging (DWI) data are typically acquired using single-shot multi-slice EPI. Images acquired with these sequences will inevitably have differences in the point-spread function along the different orientations (i.e. through-slice versus in-plane). These differences can introduce errors in the DW signal and derived parameters due to Gibbs ringing in the immediate vicinity of high signal areas (particularly CSF), which will depend on the direction of the imaging slice with respect to the direction of signal change. In this study, we demonstrate this effect by comparing images acquired using otherwise equivalent axial and sagittal DWI protocols.