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Schofield H, Boto E, Shah V, Hill RM, Osborne J, Rea M, Doyle C, Holmes N, Bowtell R, Woolger D, Brookes MJ. Quantum enabled functional neuroimaging: the why and how of magnetoencephalography using optically pumped magnetometers. CONTEMPORARY PHYSICS 2023; 63:161-179. [PMID: 38463461 PMCID: PMC10923587 DOI: 10.1080/00107514.2023.2182950] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 02/06/2023] [Indexed: 03/12/2024]
Abstract
Non-invasive imaging has transformed neuroscientific discovery and clinical practice, providing a non-invasive window into the human brain. However, whilst techniques like MRI generate ever more precise images of brain structure, in many cases, it's the function within neural networks that underlies disease. Here, we review the potential for quantum-enabled magnetic field sensors to shed light on such activity. Specifically, we describe how optically pumped magnetometers (OPMs) enable magnetoencephalographic (MEG) recordings with higher accuracy and improved practicality compared to the current state-of-the-art. The paper is split into two parts: first, we describe the work to date on OPM-MEG, detailing why this novel biomagnetic imaging technique is proving disruptive. Second, we explain how fundamental physics, including quantum mechanics and electromagnetism, underpins this developing technology. We conclude with a look to the future, outlining the potential for OPM-MEG to initiate a step change in the understanding and management of brain health.
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Affiliation(s)
- Holly Schofield
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Cerca Magnetics Limited, Nottingham, UK
| | - Elena Boto
- Cerca Magnetics Limited, Nottingham, UK
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | - Ryan M Hill
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Cerca Magnetics Limited, Nottingham, UK
| | | | - Molly Rea
- Cerca Magnetics Limited, Nottingham, UK
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | - Niall Holmes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Cerca Magnetics Limited, Nottingham, UK
| | - Richard Bowtell
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | - Matthew J Brookes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Cerca Magnetics Limited, Nottingham, UK
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Holmes N, Rea M, Chalmers J, Leggett J, Edwards LJ, Nell P, Pink S, Patel P, Wood J, Murby N, Woolger D, Dawson E, Mariani C, Tierney TM, Mellor S, O'Neill GC, Boto E, Hill RM, Shah V, Osborne J, Pardington R, Fierlinger P, Barnes GR, Glover P, Brookes MJ, Bowtell R. A lightweight magnetically shielded room with active shielding. Sci Rep 2022; 12:13561. [PMID: 35945239 PMCID: PMC9363499 DOI: 10.1038/s41598-022-17346-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/25/2022] [Indexed: 11/09/2022] Open
Abstract
Magnetically shielded rooms (MSRs) use multiple layers of materials such as MuMetal to screen external magnetic fields that would otherwise interfere with high precision magnetic field measurements such as magnetoencephalography (MEG). Optically pumped magnetometers (OPMs) have enabled the development of wearable MEG systems which have the potential to provide a motion tolerant functional brain imaging system with high spatiotemporal resolution. Despite significant promise, OPMs impose stringent magnetic shielding requirements, operating around a zero magnetic field resonance within a dynamic range of ± 5 nT. MSRs developed for OPM-MEG must therefore effectively shield external sources and provide a low remnant magnetic field inside the enclosure. Existing MSRs optimised for OPM-MEG are expensive, heavy, and difficult to site. Electromagnetic coils are used to further cancel the remnant field inside the MSR enabling participant movements during OPM-MEG, but present coil systems are challenging to engineer and occupy space in the MSR limiting participant movements and negatively impacting patient experience. Here we present a lightweight MSR design (30% reduction in weight and 40-60% reduction in external dimensions compared to a standard OPM-optimised MSR) which takes significant steps towards addressing these barriers. We also designed a 'window coil' active shielding system, featuring a series of simple rectangular coils placed directly onto the walls of the MSR. By mapping the remnant magnetic field inside the MSR, and the magnetic field produced by the coils, we can identify optimal coil currents and cancel the remnant magnetic field over the central cubic metre to just |B|= 670 ± 160 pT. These advances reduce the cost, installation time and siting restrictions of MSRs which will be essential for the widespread deployment of OPM-MEG.
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Affiliation(s)
- Niall Holmes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - Molly Rea
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - James Chalmers
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - James Leggett
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Lucy J Edwards
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Paul Nell
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Stephen Pink
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Prashant Patel
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Jack Wood
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Nick Murby
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - David Woolger
- Magnetic Shields Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Eliot Dawson
- Cerca Magnetics Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Christopher Mariani
- Cerca Magnetics Limited, Headcorn Road, Staplehurst, Tonbridge, Kent, TN12 0DS, UK
| | - Tim M Tierney
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, WC1N 3AR, UK
| | - Stephanie Mellor
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, WC1N 3AR, UK
| | - George C O'Neill
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, WC1N 3AR, UK
| | - Elena Boto
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Ryan M Hill
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Vishal Shah
- QuSpin Inc., 331 South 104th Street, Suite 130, Louisville, CO, 80027, USA
| | - James Osborne
- QuSpin Inc., 331 South 104th Street, Suite 130, Louisville, CO, 80027, USA
| | | | - Peter Fierlinger
- Department of Physics, Technical University Munich, 85748, Garching, Germany
| | - Gareth R Barnes
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, WC1N 3AR, UK
| | - Paul Glover
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Matthew J Brookes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Richard Bowtell
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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