A Comprehensive Study Of The Effects Of EEG Electrode Arrays On MRI Signal-to-noise At 3T
Goyal, Aman Ish
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Simultaneous EEG-fMRI offers much potential for gaining complementary, noninvasive information about brain function. While much effort has been devoted to the compelling problem of removing ballistocardiogram and gradient artifacts from the EEG waveforms, less attention has been paid to the impact that increasing density of electrode arrays has on the MR images. Initial work reporting the effects of EEG caps and electrodes on the MR image has been site specific, using customized EEG equipment that those research groups built in-house. Therefore these results are hard to generalize to other laboratory environments. A monotonic decrease in SNR of the images has been reported upon increasing the density of the EEG electrode array. The aim of this study was to do preliminary measurements to compare effects on MRI SNR for 32, 64 and 128 electrodes in a Compumedics-Neuroscan MagLink EEG system, using copper versus carbon - fiber cables and transmit-receive circularly polarized head coil versus 12-channel receive-only array head coil. It was found by this study that the drop in the SNR of MR images with an increase in the EEG array density is not so straight forward. It was also understood by pursuing this project that different head coils interact differently with the EEG electrode arrays.