Simultaneous EEG-fMRI at 7T: Evaluation of Radio Frequency (RF) Heating and Shielding of a novel EEG cap

Motivation: EEG-fMRI at 7T can provide very high temporal and spatial resolution, allowing non-invasive investigation of human brain function at the meso-scale. However, it presents challenges: shorter RF wavelengths may increase coupling to the EEG cap, potentially leading to B1+ shielding and increased SAR deposition. Goal(s): We investigated two iterations of a novel EEG cap designed to avoid RF coupling at 7T Approach: B1+ maps with and without EEG cap were compared to investigate shielding. Temperature changes throughout scanning duration were analysed. Results: Minimal heating at EEG electrodes was found, providing evidence that the risk of significant heating is low. B1+ were moderate. Impact: Presently, EEG-fMRI is limited by fMRI sensitivity. EEG-fMRI at 7T offers a solution to this, because fMRI signal changes are substantially increased in magnitude. This could dramatically improve the technique's sensitivity and spatial specificity for presurgical epilepsy evaluation.