Motion-induced B1+-changes in dynamic glucose enhanced (DGE) MRI and how to remedy them.

Motivation: Motion-induced B1+-changes at the voxel level result in erroneous dynamic glucose enhanced (DGE) MRI effects. Goal(s): To investigate effects of motion-induced B1+-changes on DGE MRI and to address removing them. Approach: A volunteer changed head positions, and voxel-based B1+ was measured pre- and post-motion. Z-spectra with and without D-glucose infusion were simulated, with and without the measured B1+-changes. Results: Slight motion-induced B1+-alterations lead to pseudo-CEST effects comparable to DGE effects. These can be removed by acquiring a full Z-spectrum and using the asymmetry of the glucoCEST signal relative to the water frequency to assess the DGE signal changes. Impact: Motion-induced B1+-changes affect DGE signals, thus causing pseudo-CEST effects that complicate clinical interpretation. These effects can be overcome by acquiring a full Z-spectrum and exploiting the asymmetry of the glucoCEST signal changes relative to the water frequency.