Requirements for Coregistration Accuracy in On-Scalp MEG

Area of Science:

• Biophysics
• Neuroscience
• Biomedical Engineering

Background:

• Optically-pumped magnetometers (OPMs) enable on-scalp magnetoencephalography (MEG) due to their high sensitivity and lack of need for cryogenic cooling.
• Unlike rigid SQUID-based systems, OPMs allow for adaptable sensor arrays conforming to the head, posing new challenges for sensor-to-head registration.

Purpose of the Study:

• To quantify the required accuracy for sensor position and orientation in on-scalp MEG systems using simulations.
• To investigate the impact of different localization errors on forward modeling and neural source estimation techniques.

Main Methods:

• Simulations were conducted to assess the impact of sensor position and orientation errors on MEG data.
• Analysis included evaluating effects on minimum-norm estimation, dipole fitting, and beamforming source localization algorithms.

Main Results:

• Sensor position errors generally have a greater impact on source localization accuracy than orientation errors.
• Superficial neural sources are most affected by sensor localization inaccuracies.
• To match or exceed current SQUID-based MEG accuracy, root-mean-square (RMS) sensor position and orientation errors should be within specific thresholds.

Conclusions:

• Accurate sensor coregistration is critical for on-scalp OPM-MEG systems.
• The findings provide essential guidelines for designing and implementing high-accuracy on-scalp MEG systems.