Simultaneously detected biomagnetic signals and NMR

We have obtained 1H NMR spectra simultaneously with high temporal resolution biomagnetic signals such as the magnetocardiogram (MCG) and magnetomyogram (MMG). The NMR spectra are acquired at measurement fields of 2-50 microT, with corresponding proton Larmor frequencies of 80-2000 Hz. Our measurements demonstrate a method suitable for MR imaging with concurrent measurement of biomagnetic signals that can provide sub-millisecond temporal resolution. The narrow line widths, reduction in susceptibility noise and enhanced spectral resolution at ultra low fields provide a new and extremely sensitive measurement method that may enable direct imaging of biological currents by detecting the phase or frequency shifts produced by magnetic fields arising from those currents. The results of our simultaneous measurements of NMR with MCG and MMG are compared to results from a current phantom to investigate the exciting potential of direct MRI of bioelectric currents.