Arnold Skimminge1,2, Mark Schram Christensen1,3
1Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark; 2DTU Informatics, Technical University of Denmark, Lyngby, Denmark; 3Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
High-speed MRI gradients tend to be nonlinear outside the center of the magnetic field. This introduces structural deformations which may influence not only the shape of structural images but also the location of activation in fMRI studies. In worst case scenarios it could have serious impact for presurgical planning fMRI studies if activation gets mislocalised. Here we show that even in a best case scenario where functional images are normalised, smoothed and group activation maps created, there is still a significant difference in activation localisation with and with a correction for the gradient nonlinearities.