A B(0) shift correction method based on edge RMS reduction for EPI fMRI

Shifting of echoplanar images (EPI) in the phase-encoding direction during functional magnetic resonance imaging (fMRI) experiments can be observed due to B(o) drift. These shifts can cause artifacts in functional activation maps that can be corrected using a navigator echo (NE) technique, but the NE correction requires pulse sequence modifications not available on many clinical systems. A fast, postprocessing correction method based on edge root-mean-square error reduction (ERMSR) is introduced and shown to provide an equivalent correction. (C) 2000 Wiley-Liss, Inc.