Source reconstruction without an MRI using optically pumped magnetometer-based magnetoencephalography

Area of Science:

• Neuroscience
• Biophysics
• Medical Imaging

Background:

• Magnetoencephalography (MEG) source modeling typically requires individual MRI scans.
• Wearable MEG using optically pumped magnetometers (OPMs) expands research to new populations but is limited by MRI dependency.
• Accurate source localization is crucial for understanding brain activity.

Purpose of the Study:

• To develop and validate a method for generating pseudo-MRIs from 3D structured-light scans for OPM-MEG source modeling.
• To assess the comparability of OPM-MEG data modeled with pseudo-MRIs versus traditional MRIs.
• To overcome the challenge of acquiring individual MRI scans in OPM-MEG studies.

Main Methods:

• Developed a warping technique to create pseudo-MRIs from 3D structured-light head scans.
• Applied the method to 20 participants performing a sensory task using OPM-MEG.
• Analyzed task-induced beta band responses and whole-brain functional connectivity.

Main Results:

• Peak task-induced beta modulation locations showed minimal separation (2.75 mm) between real and pseudo-MRI approaches.
• Group-averaged time-frequency spectra, functional connectome matrices, and global connectivity demonstrated high correlations (0.99, 0.87, 0.98 respectively).
• Source-localized OPM-MEG data modeled with and without individual MRI scans yielded comparable results.

Conclusions:

• The pseudo-MRI method provides a viable alternative when individual MRI acquisition is challenging for OPM-MEG.
• This approach enhances the accessibility and applicability of OPM-MEG for studying diverse populations.
• While individual MRIs remain the gold standard, pseudo-MRIs offer valuable utility for specific research scenarios.