OPM-MEG/ULF-MRI Hybrid System: towards acquisition of both MR image and neural magnetic field

Motivation: To overcome the limitations of signal co-registration in MEG, we constructed MEG/MRI hybrid system. Goal(s): To demonstrate feasibility of this system. High-sensitivity OPMs in a reasonable magnetic shield with MRI system. Approach: Phantom experiments. Phantom includes triangle coil and MEG measures its magnetic field. MRI scanned this phantom with 3D-SE sequence. Results: We recognized signal peak generated by 100 nAm current dipole moment in amplitude spectrum density visually. We also confirmed the structure of the phantom in 3D MR images. Impact: We made MEG/MRI hybrid system for the purpose of accurate signal co-registration between them. MEG employed scalar-mode OPM, and its noise level was 367 fT/rHz. We scanned phantom using 7-mT MRI scanner and confirmed its structure.