Characterization and Correction of Physiological Instabilities in 3D FMRI

3D readouts generally have the advantage that they 1) allow imaging at a high isotropic resolution and 2) are inherently multi-shot sequences with short readout segments thereby reducing distortion artifacts. These advantages make sequences such as steady-state free-precession (SSFP) and spoiled gradient echo (SPGR) an attractive option for high resolution FMRI in areas such as the brainstem. Experiments have shown however that these sequences are prone to temporal instabilities in inferior areas of the brain (Fig. 1). In this work we present a characterisation of these instabilities by simulations and report preliminary results of a GRAPPA-based correction method that utilizes the additional information of the coil geometry to allow retrospective gating of 3D FMRI data.