Reducing the Gradient Artefact in Simultaneous EEG-fMRI by Adjusting the EEG Cap Lead Configuration

Karen J. Mullinger¹, Muhammad E.H. Chowdhury², Richard W. Bowtell²

EEG data recorded simultaneously with fMRI acquisition are contaminated by large voltages generated by the time-varying magnetic field gradients. Previous work suggested changing the EEG cap lead layout and cable bundle position could reduce the gradient artefact (GA). Here, through simulations and experiments, we show that a reduction of the GA can be achieved through the suggested modifications. Using a modified cap, we experimentally demonstrate significant reduction in the GA amplitude over the temple regions using a standard EPI sequence. Different lead configurations could be explored to minimise the GA for other electrodes depending on the cortical areas of interest.