Simultaneous EEG–fMRI at 3 Tesla was performed in nine normal human subjects (8–11 runs/subject, 5.52 min/run). Gradient switching artifact was effectively reduced using commercially supplied procedures. Cardiac beats were detected using a novel correlation detector algorithm applied to the EKG trace. BKG artifact was reduced using both mGLM and AAS.
mGLM recovered BKG waveforms outlasting the median inter-beat interval. mGLM more effectively than AAS removed variance in the EEG attributable to BKG artifact.
mGLM offers advantages over AAS especially in the presence of variable heart rate.
The BKG artifact reduction procedure described herein improves the technique of simultaneous EEG–fMRI. Potential applications include basic investigations of the relationship between scalp potentials and functional imaging signals as well as clinical localization of epileptic foci.