EEG recording during fMRI experiments: Image quality

Electroencephalographic (EEG) monitoring during functional magnetic resonan ce imaging (fMRI) experiments is increasingly applied for studying physiolo gical and pathological brain function. However, the quality of the fMRI dat a can be significantly compromised by the EEG recording due to the magnetic susceptibility of the EEG electrode assemblies and electromagnetic noise e mitted by the EEG recording equipment. We therefore investigated the effect of individual components of the EEG recording equipment on the quality of echo planar images. The artifact associated with each component was measure d and compared to the minimum scalp-cortex distance measured in normal cont rols. The image noise originating from the EEG recording equipment was iden tified as coherent noise and could be eliminated by appropriate shielding o f the EEG equipment. It was concluded that concurrent EEG and fMRI could be performed without compromising the image quality significantly if suitable equipment is used. The methods described and the results of this study sho uld be useful to other researchers as a framework for testing of their own equipment and for the selection of appropriate equipment for EEG recording inside a MR scanner. Hum. Brain Mapping 10:10-15, 2000. (C) 2000 Wiley-Liss , Inc.