On the potential of a new generation of magnetometers for MEG: a beamformer simulation study

Boto, Elena and Bowtell, Richard W. and Kruger, Peter and Fromhold, T. Mark and Morris, Peter G. and Meyer, Sofie S. and Barnes, Gareth R. and Brookes, Matthew J. (2016) On the potential of a new generation of magnetometers for MEG: a beamformer simulation study. PLoS ONE, 11 (8). e0157655/1- e0157655/24. ISSN 1932-6203

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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.

Item Type: Article
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: https://doi.org/10.1371/journal.pone.0157655
Depositing User: Boto, Elena
Date Deposited: 26 Oct 2016 10:25
Last Modified: 27 Oct 2016 08:43
URI: http://eprints.nottingham.ac.uk/id/eprint/37932

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