Simultaneous magnetoencephalography and SQUID detected nuclear MR in microtesla magnetic fields

A system that simultaneously measures magnetoencephalography (MEG) and nuclear magnetic resonance (NMR) signals from the human brain was designed and fabricated. A superconducting quantum interference device (SQUID) sensor coupled to a gradiometer pickup coil was used to measure the NMR and MEG signals. H-1 NMR spectra with typical Larmor frequencies from 100-1000 Hz acquired simultaneously with the evoked MEG response from a stimulus to the median nerve are reported. The single SQUID gradiometer was placed approximately over the somatosensory cortex of a human subject to noninvasively record the signals. These measurements demonstrate, for the first time, the feasibility of simultaneous MRI and MEG. NMR in the microtesla regime provides narrow line-widths and the potential for high spatial resolution imaging, while SQUID sensors enable direct measurement of neuronal activity with high temporal resolution via MEG. (C) 2004 Wiley-Liss, Inc.