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.
Meagher et al. (Tue,) studied this question.