An advanced phantom study assessing the feasibility of neuronal current imaging by ultra-low-field NMR.

摘要: Abstract In ultra-low-field (ULF) NMR/MRI, a common scheme is to magnetize the sample by polarizing field of up hundreds mT, after which NMR signal, precessing in on order several μT, detected with superconducting quantum interference devices (SQUIDs). our ULF-NMR system, we polarize 50 mT and deploy single-stage DC-SQUID current sensor an integrated input coil connected wire-wound Nb gradiometer. We developed this system (white noise 0.50 fT/ Hz ) for assessing feasibility imaging neuronal currents detecting their effect signal. Magnetoencephalography investigations evoked brain activity showed dipole moments below 50 nAm. With instrumentation, have studied two different approaches imaging. so-called DC effect, long-lived shifts Larmor frequency surrounding protons. An alternative strategy exploit fast as tipping pulse. This AC requires proton match activity, ranges from near-DC ∼kHz. emulated means single dipolar source physical phantom, consisting hollow sphere filled aqueous solution CuSO4 NaCl. these phantom studies, physiologically relevant depths, determined resolution limits set-up ∼10 μAm ∼50 nAm, respectively. Hence, appears be detectable vivo technology.