High-efficiency co-registration of OPM-MEG and MRI using point cloud processing.

Optically pumped magnetometers (OPMs) offer high temporal and spatial resolution for magnetoencephalography (MEG) applications, particularly in noninvasive brain mapping and epilepsy diagnosis. However, effective MEG-MRI co-registration remains challenging. This study presents a novel co-registration technique utilizing OPMs to achieve rapid registration speeds and submillimeter precision, addressing the limitations of traditional methods. We developed an indirect registration method that integrates a marker module with an optimized fast and robust iterative closest point (FRICP) algorithm and principal component analysis (PCA), resulting in a 27% increase in efficiency. The custom MEG helmet enables rapid 3D facial digitization, reducing scanning time to an average of 20 seconds-the fastest reported-while minimizing errors due to cable obstructions. Experimental validation demonstrated absolute position errors of 0.49 mm and orientation errors of 0.17°, confirming the technique's accuracy. This approach addresses critical registration challenges and holds significant potential to advance MEG technology and improve neurological disorder diagnostics.