Evaluating the effect of OPM array errors on the multiple dipole localization accuracy of OPM-MEG

The use of optically pumped magnetometers (OPMs) has provided a feasible, moveable and wearable alternative to superconducting detectors for magnetoencephalography (MEG) measurement. The multiple dipole localization in MEG is a common and complicated problem. In this paper, we constructed an OPM-MEG simulation pipeline for multiple dipole localization using a recently proposed novel solution called Alternating Projection (AP) and its extension algorithms. Three type OPM arrays including single, dual and triple sensitive axis were used for simulation with considering sensor calibration errors and position error. The localization accuracy performance was assessed with altering the simulated source number, SNR and the inter-source coupling strength. Two metrics for evaluating the localization performance including distance of localization error (DLE) and relative mean squared error (RMSE) between simulated and source time course indicated a better accuracy of the AP method using dual and triple sensitive axis. In addition, the results showed that AP method suffered from calibration errors and position error of OPM array, which highlighted the importance of OPM calibration prior to its use in MEG measurements.