Retrospective removal of k-space artifacts for echo-planar images: Noise reduction algorithms for spike suppression

High demands are made of the gradient systems of MRI scanners during acquisition of echo-planar images. These may occasionally lead to spurious noise added to the received data in the form of short duration, high intensity "spikes." If these spikes are not caught prior to image formation, a severely degraded image may be formed. In the acquisition of functional MRI data this degradation may prohibit subsequent analysis of the data for identification of activated brain regions. We have devised several algorithms to isolate and remove these spurious spikes prior to the Fourier transform, and in one example show that subsequent fMRI analyses are possible. By contrast, the analysis is either impossible or produces differing results without this processing step.