A Sensor Localization and Orientation Method for OPM-MEG Based on Rigid Coil Structures and Magnetic Dipole Fitting...

Area of Science:

• Biomedical Engineering
• Neuroscience Instrumentation
• Medical Imaging Physics

Background:

• High-precision sensor co-registration is essential for high-resolution Optically Pumped Magnetometer-Magnetoencephalography (OPM-MEG) imaging.
• Conventional magnetic dipole fitting methods have limitations in accuracy due to geometric factors and approximation errors, especially in near-field conditions.

Purpose of the Study:

• To develop and validate a novel sensor localization and orientation method for OPM-MEG systems.
• To improve the accuracy and robustness of sensor co-registration in OPM-MEG.

Main Methods:

• A method combining magnetic dipole-equivalent modeling with a rigid coil structure (RCS) for stable geometric constraints.
• Formulation of three objective functions: standard Frobenius norm, weighted Frobenius norm, and structural similarity index (SSIM).
• Simulation-based evaluation under ideal conditions and assembly perturbations.

Main Results:

• The weighted Frobenius norm and SSIM methods achieved position errors below 1 mm and orientation errors below 1°.
• These methods demonstrated superior performance by suppressing outlier deviations compared to the standard Frobenius norm.
• The proposed method showed high accuracy and robustness even with assembly perturbations.

Conclusions:

• The developed method effectively addresses the limitations of conventional approaches for OPM-MEG sensor co-registration.
• It provides a geometry-constrained, optimization-based framework for practical, high-precision, multi-channel OPM-MEG system implementation.
• The findings clarify factors influencing magnetic dipole approximation errors and offer a pathway for improved OPM-MEG technology.