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Updated: Sep 30, 2025

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Using OPM-MEG in contrasting magnetic environments.

Ryan M Hill1, Jasen Devasagayam2, Niall Holmes1

  • 1Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK; Cerca Magnetics Limited, Headcorn Road, Staplehurst, Kent, UK.

Neuroimage
|March 12, 2022
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Optically pumped magnetometer-magnetoencephalography (OPM-MEG) systems demonstrate reliable, comparable data across different magnetic environments. This breakthrough allows OPM-MEG to be implemented in diverse locations, including city hospitals, expanding its applications.

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Area of Science:

  • Biophysics
  • Neuroscience
  • Biomedical Engineering

Background:

  • Optically pumped magnetometers (OPMs) have significantly advanced magnetoencephalography (MEG), offering superior sensitivity, spatial resolution, and portability compared to traditional superconducting quantum interference devices (SQUIDs).
  • The potential for motion robustness and wider application range makes OPM-MEG a promising technology, yet its reliability across different environments and the need for stringent magnetic shielding remain challenges.
  • Current OPM-MEG systems are largely custom-made, with a lack of cross-site validation hindering widespread adoption and standardization.

Purpose of the Study:

  • To conduct the first cross-site comparison of near-identical commercial OPM-MEG systems.
  • To evaluate the reliability and comparability of OPM-MEG data acquired in contrasting magnetic environments.
  • To demonstrate the feasibility of implementing OPM-MEG in non-ideal locations, such as city centre hospitals.

Main Methods:

  • Utilized two near-identical commercial OPM-MEG systems at contrasting sites: a low-interference campus university with an OPM-optimized shielded room and a high-interference city centre hospital with a standard magnetic shielding room.
  • Employed dynamic field control and software-based interference suppression techniques to mitigate environmental magnetic field differences.
  • Recorded human data during a visuo-motor task and a face processing paradigm for comparative analysis.

Main Results:

  • Achieved comparable noise floors at both sites despite a 20-fold difference in background field and a 30-fold difference in low-frequency interference.
  • Generated similar human data across both sites, with brain region source localization showing a spatial discrepancy of approximately 10 mm.
  • Demonstrated high temporal correlations (>80%) in the recorded brain activity between the two sites.

Conclusions:

  • OPM-MEG systems can produce reliable and comparable neurophysiological data even in challenging magnetic environments, such as city centre hospitals, with appropriate field control.
  • The demonstrated methods for dynamic field control and interference suppression are crucial for overcoming environmental limitations and ensuring data consistency.
  • This study validates the potential for wider deployment and standardization of OPM-MEG technology, paving the way for its increased use in clinical and research settings.