Design and Fabrication of an Anatomically Realistic Multimodal EEG/MEG Head Phantom

Accurate electromagnetic head phantoms are important tools for validating electroencephalography (EEG) and magnetoencephalography (MEG) devices and techniques. A combined M/EEG phantom would be particularly useful for its ability to test and validate multimodal imaging methods. However, EEG and combined M/EEG phantoms remain commercially unavailable, and phantoms in published literature require materials research and development processes that are difficult to complete or replicate. Here, we detail steps to create a highly realistic four-layer, desktop M/EEG phantom and demonstrate simultaneous EEG and MEG recordings of signals generated from within the phantom.

Utilizing materials and methods accessible to biomedical professionals, we provide detailed instructions to create, maintain, and use an M/EEG phantom with four layers including the scalp, compact bone, spongy bone, and brain layers. We also demonstrate its use by stimulating the phantom with dipole sources at four cortical locations using current-controlled signals of varying frequencies and amplitudes.

The resulting phantom is anatomically and electrically realistic, with skin and brain layer resistivities of 2.668 Ω·m each, and average bulk skull resistivity of 169.2 Ω·m. The dipole stimulations also resulted in biologically realistic scalp maps and measured signal amplitudes in both the EEG and MEG.

The instructions presented here produce a combined M/EEG phantom that exhibits biologically realistic forward physics using materials and methods available to a biomedical professional.

With these instructions, we make electromagnetic head phantoms more accessible to researchers, improving their ability to test and validate EEG, MEG, and combined devices and techniques.