Iterative motion compensation and estimation in magnetic resonance imaging (MRI)

Motion artifacts in magnetic resonance images result from displacement of “isochromats” during the imaging interval. This motion is categorized into two classes: Motion within a Free Induction Decay (FID) and motion between FID excitations. Furthermore, local regions in the spatial data being measured generally undergo unique motion profiles for each class, and each class may not consist of the same local segmentation. Models for each class are presented using a general digital signal processing (DSP) format and conversions from real world parameters to this normalized DSP domain are given. A multilevel motion model is then given, suggesting a layered approach to removing the spatial and class variant distortion functions. Finally, a method and simulation is presented for removing one of the more troublesome of these artifact layers, global patient movement.