![]() ![]() ![]() The results for both models are encouraging. The transformation results are characterized by a relative error and cross-correlation between the measured and the estimated magnetic field maps of the AEFs. Two different volume conductor models were compared: the homogeneous conducting sphere and the three-shell model of the head. ![]() For the source reconstruction, we used a minimum norm estimate (MNE) of the current distribution. This approach works on the principle of solving the inverse problem with one system, and then using the forward model to calculate the magnetic fields expected for the other system. We present a theoretical framework that transforms the within subject data and equivalent simulation data from one MEG system to the other. Here, we measured auditory evoked fields (AEFs) with both SQUID- and OPM-based MEG systems for a group of subjects to better understand the usage of a limited sensor count OPM-MEG. ![]() Therefore, they can be placed closer to the scalp and are much easier to use. The main advantage of OPMs is that they do not require cryogenics for cooling. These sensors solve operational problems of the current standard MEG, where superconducting quantum interference device (SQUID) gradiometers and magnetometers are being used. Optically pumped magnetometers (OPMs) have recently become so sensitive that they are suitable for use in magnetoencephalography (MEG). ![]()
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