Improvement to functional Magnetic Resonance Imaging (fMRI) Methods using Non-rigid Body Image Registration Methods for Correction in the Presence of Susceptibility Artifact Effects

Subject head movement, during the experimental and/or clinical procedure is an inevitable part of the functional magnetic resonance imaging (fMRI) brain mapping methods despite the availability of a large variety of head fixation devices employed in these studies. Thus, image registration is an essential processing step in fMRI. This is due to the fact that there is inevitable movement during the course on an fMRI experiment. An additional challenge is the explicit geometrical deformations associated with MRI. It is known that orientational changes are problematic in MRI in the presence of susceptibility differences especially between bone-tissue and air-tissue interfaces. This paper presents two registration strategies for fMRI registration, one using rigid registration based on maximization of mutual information, and the second is non-rigid registration adapted from Thirion´s demons algorithm to demonstrate the importance and impact on fMRI in regions of susceptibility and its dependence on the image registration methodology