{"paper_id":"15c2c682-35a3-4d8f-962d-2d0b3e227fd5","body_text":"Beam-Forming for Whole-Body Travelling-wave MRI at Ultra-High-Field | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Beam-Forming for Whole-Body Travelling-wave MRI at Ultra-High-Field Xiaotong Zhang, Yang Gao, Qilong Wang, Tong Liu, Haiwei Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5838850/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In clinical magnetic resonance imaging (MRI), uniform nuclei-spin excitation via the circularly polarized transverse magnetic field is crucial. Ultra-High-Field (UHF, ≥7T) MRI is of great significance in medical imaging due to higher signal-to-noise ratio (SNR). However, higher operating frequency (≥ 297 MHz) at UHF MRI makes it challenge to achieve uniform nuclei-spin excitation, since the human body behaves as an electrically large object. The wave-behavior dominates field distribution inside biological tissues instead of the quasi-static principle. Following the classical volume layout for current sources, it forms multi-beam transmission condition, which inevitably led to prominent standing-wave patterns. It is good for targeted focusing application but detrimental to large-scale nuclei-spin excitation at UHF MRI. Waveguide based travelling-wave MRI is a promising alternative to achieve single-beam transmission, but its major power is blocked by the head and extremities. Therefore, it is not suitable to whole-body MRI. Our study presents a novel single-beam transmission strategy for whole-body application through beam-forming in a center-fed waveguide system. The inner metallic bore of MRI system as well as the dielectric material were used to achieve effective beam-forming inside biological tissues. The role of phase-velocity matching and wave-impedance matching in alleviating scattering effect arising from highly non-unform dielectric media, were also explored in this study. Preliminary phantom validation and in vivo scans of the spine, thorax, abdomen, and pelvis show the potential of this method for whole-body MRI at UHF. Physical sciences/Optics and photonics/Optical techniques/Imaging and sensing Physical sciences/Engineering/Electrical and electronic engineering Physical sciences/Engineering/Biomedical engineering Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-5838850\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":566302598,\"identity\":\"1b1f2e4a-964f-4092-82e9-aa1bccd4884b\",\"order_by\":0,\"name\":\"Xiaotong 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