{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T20:24:13Z","timestamp":1775075053310,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2024,5,29]],"date-time":"2024-05-29T00:00:00Z","timestamp":1716940800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Canadian Foundation for Innovation and Research Nova Scotia","award":["38127"],"award-info":[{"award-number":["38127"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Magnetoencephalography (MEG) non-invasively provides important information about human brain electrophysiology. The growing use of optically pumped magnetometers (OPM) for MEG, as opposed to fixed arrays of cryogenic sensors, has opened the door for innovation in system design and use cases. For example, cryogenic MEG systems are housed in large, shielded rooms to provide sufficient space for the system dewar. Here, we investigate the performance of OPM recordings inside of a cylindrical shield with a 1 \u00d7 2 m2 footprint. The efficacy of shielding was measured in terms of field attenuation and isotropy, and the value of post hoc noise reduction algorithms was also investigated. Localization accuracy was quantified for 104 OPM sensors mounted on a fixed helmet array based on simulations and recordings from a bespoke current dipole phantom. Passive shielding attenuated the vector field magnitude to 50.0 nT at direct current (DC), to 16.7 pT\/\u221aHz at power line, and to 71 fT\/\u221aHz (median) in the 10\u2013200 Hz range. Post hoc noise reduction provided an additional 5\u201315 dB attenuation. Substantial field isotropy remained in the volume encompassing the sensor array. The consistency of the isotropy over months suggests that a field nulling solution could be readily applied. A current dipole phantom generating source activity at an appropriate magnitude for the human brain generated field fluctuations on the order of 0.5\u20131 pT. Phantom signals were localized with 3 mm localization accuracy, and no significant bias in localization was observed, which is in line with performance for cryogenic and OPM MEG systems. This validation of the performance of a small footprint MEG system opens the door for lower-cost MEG installations in terms of raw materials and facility space, as well as mobile imaging systems (e.g., truck-based). Such implementations are relevant for global adoption of MEG outside of highly resourced research and clinical institutions.<\/jats:p>","DOI":"10.3390\/s24113503","type":"journal-article","created":{"date-parts":[[2024,5,29]],"date-time":"2024-05-29T06:58:07Z","timestamp":1716965887000},"page":"3503","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Noise Reduction and Localization Accuracy in a Mobile Magnetoencephalography System"],"prefix":"10.3390","volume":"24","author":[{"given":"Timothy","family":"Bardouille","sequence":"first","affiliation":[{"name":"Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2, Canada"}]},{"given":"Vanessa","family":"Smith","sequence":"additional","affiliation":[{"name":"Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2, Canada"}]},{"given":"Elias","family":"Vajda","sequence":"additional","affiliation":[{"name":"Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2, Canada"}]},{"given":"Carson Drake","family":"Leslie","sequence":"additional","affiliation":[{"name":"Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2, Canada"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0561-8366","authenticated-orcid":false,"given":"Niall","family":"Holmes","sequence":"additional","affiliation":[{"name":"Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK"},{"name":"Cerca Magnetics Limited, Units 7\u20138 Castlebridge Office Village, Kirtley Drive, Nottingham NG7 1LD, UK"}]}],"member":"1968","published-online":{"date-parts":[[2024,5,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3059","DOI":"10.1093\/brain\/awz231","article-title":"Magnetoencephalography for epileptic focus localization in a series of 1000 cases","volume":"142","author":"Rampp","year":"2019","journal-title":"Brain"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1080\/00107514.2023.2182950","article-title":"Quantum enabled functional neuroimaging: The why and how of magnetoencephalography using optically pumped magnetometers","volume":"63","author":"Schofield","year":"2022","journal-title":"Contemp. 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