Characterization of a flexible cap for simultaneous OPM-MEG and EEG measurements

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Imaging

Background:

• Simultaneous Magnetoencephalography (MEG) and Electroencephalography (EEG) enhance source reconstruction accuracy.
• Previous Optically Pumped MEG (OPM-MEG) setups with EEG used rigid helmets, reducing OPM signal amplitude and user comfort.
• Rigid OPM-MEG systems require customization, are heavy, and do not adapt to individual head shapes, limiting OPM-MEG's advantages.

Purpose of the Study:

• To develop a flexible cap for fully integrated simultaneous OPM-MEG and EEG measurements.
• To ensure the integrated system is suitable for source reconstruction.
• To achieve signal quality comparable to individual modalities.

Main Methods:

• Integrated OPM mounts into a commercial EEG cap.
• Developed a sensor localization pipeline using 3D scans and OPM mount geometry.
• Assessed OPM shifts during experiments with five volunteers using a multi-paradigm design.
• Compared signal-to-noise ratios and artifact strengths between single-modality and multimodal acquisitions.

Main Results:

• OPM position and orientation shifts were within acceptable limits for source reconstruction.
• Larger shifts were observed in occipital OPMs.
• No significant differences in signal-to-noise ratios or artifact strengths were found between single-modality and multimodal measurements.
• The integrated system demonstrated no signal degradation.

Conclusions:

• Simultaneous OPM-MEG and EEG using a flexible cap can improve source reconstruction.
• This approach facilitates the clinical adoption of OPM-MEG by enabling easier comparison with established EEG.
• The technology is relevant for presurgical epilepsy evaluation.