title: On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study.
abstract: Magnetoencephalography (MEG) is a sophisticated tool which yields rich information on the spatial, spectral and temporal signatures of human brain function. Despite unique potential, MEG is limited by a low signal-to-noise ratio (SNR) which is caused by both the inherently small magnetic fields generated by the brain, and the scalp-to-sensor distance. The latter is limited in current systems due to a requirement for pickup coils to be cryogenically cooled. Recent work suggests that optically-pumped magnetometers (OPMs) might be a viable alternative to superconducting detectors for MEG measurement. They have the advantage that sensors can be brought to within ~4 mm of the scalp, thus offering increased sensitivity. Here, using simulations, we quantify the advantages of hypothetical OPM systems in terms of sensitivity, reconstruction accuracy and spatial resolution. Our results show that a multi-channel whole-head OPM system offers (on average) a fivefold improvement in sensitivity for an adult brain, as well as clear improvements in reconstruction accuracy and spatial resolution. However, we also show that such improvements depend critically on accurate forward models; indeed, the reconstruction accuracy of our simulated OPM system only outperformed that of a simulated superconducting system in cases where forward field error was less than 5%. Overall, our results imply that the realisation of a viable whole-head multi-channel OPM system could generate a step change in the utility of MEG as a means to assess brain electrophysiological activity in health and disease. However in practice, this will require both improved hardware and modelling algorithms.
authors: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: Elena
authors: E
authors: Boto
authors: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: Richard
authors: R
authors: Bowtell
authors: Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: Peter
authors: P
authors: Krüger
authors: Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: T Mark
authors: TM
authors: Fromhold
authors: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: Peter G
authors: PG
authors: Morris
authors: Wellcome Trust Centre for Neuroimaging, University College London, 12 Queen Square, WC1N 3BG, London, United Kingdom.
authors: Sofie S
authors: SS
authors: Meyer
authors: Wellcome Trust Centre for Neuroimaging, University College London, 12 Queen Square, WC1N 3BG, London, United Kingdom.
authors: Gareth R
authors: GR
authors: Barnes
authors: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, United Kingdom.
authors: Matthew J
authors: MJ
authors: Brookes
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000473:pathology; D001931:Brain Mapping; D003198:Computer Simulation; D004594:Electrophysiology; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015225:Magnetoencephalography / Q000295:instrumentation*; D055095:Optics and Photonics; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio