Enlighten Publications

In this section

Ultra-high field MRI: parallel-transmit arrays and RF pulse design

Williams, S. N. , McElhinney, P. and Gunamony, S. (2023) Ultra-high field MRI: parallel-transmit arrays and RF pulse design. Physics in Medicine and Biology, 68(2), 02TR02. (doi: 10.1088/1361-6560/aca4b7)

Text
289776.pdf - Published Version
Available under License Creative Commons Attribution.
2MB

Abstract

This paper reviews the field of multiple or parallel radiofrequency (RF) transmission for magnetic resonance imaging (MRI). Currently the use of ultra-high field (UHF) MRI at 7 tesla and above is gaining popularity, yet faces challenges with non-uniformity of the RF field and higher RF power deposition. Since its introduction in the early 2000s, parallel transmission (pTx) has been recognized as a powerful tool for accelerating spatially selective RF pulses and combating the challenges associated with RF inhomogeneity at UHF. We provide a survey of the types of dedicated RF coils used commonly for pTx and the important modeling of the coil behavior by electromagnetic (EM) field simulations. We also discuss the additional safety considerations involved with pTx such as the specific absorption rate (SAR) and how to manage them. We then describe the application of pTx with RF pulse design, including a practical guide to popular methods. Finally, we conclude with a description of the current and future prospects for pTx, particularly its potential for routine clinical use.

Item Type:	Articles
Keywords:	Radiofrequency (RF) coils, ultra-high field (UHF) magnetic resonance imaging (MRI), parallel transmission (pTx), electromagnetic (EM) fields, specific absorption rate (SAR).
Status:	Published
Refereed:	Yes
Glasgow Author(s) Enlighten ID:	Gunamony, Dr Shajan and Williams, Dr Sydney and McElhinney, Dr Paul
Authors:	Williams, S. N., McElhinney, P., and Gunamony, S.
Subjects:	Q Science > Q Science (General) R Medicine > R Medicine (General)
College/School:	College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Research Group:	Imaging Centre of Excellence
Journal Name:	Physics in Medicine and Biology
Journal Abbr.:	Phys Med Biol
Publisher:	IOP Publishing
ISSN:	0031-9155
ISSN (Online):	1361-6560
Published Online:	18 January 2023
Copyright Holders:	Copyright © 2023 The Authors
First Published:	First published in Physics in Medicine and Biology 68(2): 02TR02
Publisher Policy:	Reproduced under a Creative Commons License

University Staff: Request a correction | Enlighten Editors: Update this record

Funder and Project Information

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
307557		the Living Lab: driving economic growth in Glasgow through real world implementation of precision medicine	Carol Clugston	UK Research and Innovation ( UKRI) (UKRI)	19176 The living lab	MVLS - College Senior Management
313015		Development of a Novel Head Coil for Clinical Neuroimaging in 7 Tesla MRI Scanners	David Porter	Innovate UK (INNOVATE)	93468	Centre for Neuroscience

References

Ackerman J J H, Grove TH, WongGG, GadianDGand RaddaGK1980 Mapping of metabolites in whole animals by 31PNMRusing surface coils Nature 283 167–70 Adriany G, Auerbach E J, SnyderCJ, Gözübüyük A, Moeller S, Ritter J, Van de Moortele P-F, Vaughan T andUğurbilK2010 A32-channel lattice transmission line array for parallel transmit and receive MRI at 7 tesla Magnetic Resonance in Medicine 63 1478–85 Adriany G, Van de Moortele P-F, Ritter J, Moeller S, Auerbach E J, Akgün C, SnyderCJ, Vaughan T andUğurbilK2008 A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 tesla Magnetic Resonance in Medicine 59 590-597 AdrianyGet al 2019 Evaluation of a 16-Channel Transmitter for Head Imaging at 10.5T Int. Conf. on Electromagnetics in Advanced Applications (ICEAA) (Piscataway, NJ) (IEEE) (Granada, Spain) pp 1171–4 Adriany G, Van de Moortele P-F, Wiesinger F, Moeller S, Strupp J P, Snyder C, Zhang X, Chen W, PruessmanKP, Boesinger P, Vaughan T, UğurbilKet al 2005 Transmit and receive transmission line arrays for 7 Tesla parallel imaging Magnetic Resonance in Medicine 53 434–45 AignerCS, Dietrich S, Schaeffter T and Schmitter S 2022 Calibration-free pTx of the human heart at 7T via 3D universal pulses Magnetic Resonance Medicine 87 70–84 AignerCS, Rund A, Abo Seada S, Price AN, Hajnal JV, Malik S J, Kunisch Kand Stollberger R 2019 Time optimal control-based RF pulse design under gradient imperfections Magnetic Resonance in Medicine mrm.27955 83 561–74 Ajanovic A, Hajnal JVand Malik S J 2020 Positional sensitivity of specific absorption rate in head at 7T International Society for Magnetic Resonance in Medicine. (Virtual, 08/2020 pp 4251) pp 4251 AvdievichNI 2011 Transceiver-phased arrays for human brain studies at 7 T Applied Magnetic Resonance 41 483–506 AvdievichNI, Giapitzakis I A, Bause J, Shajan G, SchefflerKand Henning A 2019 Double-row 18-loop transceive–32-loop receive tight-fit array provides for whole-brain coverage, high transmit performance, and SNR improvement near the brain center at 9.4T Magnetic Resonance in Medicine 81 3392–405 AvdievichNI, Hoffmann J, Shajan G, Pfrommer A, Despotović I, SchefflerKand Henning A2017 Evaluation of transmit efficiency and SAR for a tight fit transceiver human head phased array at 9.4 TNMRin Biomedicine 30 1–12 AvdievichNI, Nikulin AV,Ruhm L, Magill AW, Glang F, Henning A and SchefflerK2022 A 32-element loop/dipole hybrid array for human head imaging at 7T Magnetic Resonance in Medicine 88 1912–26 AvdievichNI, Pan JWand HetheringtonHP 2013 Resonant inductive decoupling (RID) for transceiver arrays to compensate for both reactive and resistive components of the mutual impedanceNMRin Biomedicine 26 1547–54 AvdievichNI, Solomakha G, Ruhm L, Henning A and SchefflerK2021 Unshielded bent folded-end dipole 9.4 T human head transceiver array decoupled using modified passive dipoles Magnetic Resonance in Medicine 86 581–97 AvdievichNI, Solomakha G, Ruhm L, SchefflerKand Henning A 2020 Decoupling of folded-end dipole atenna elements of a 9.4 T human head array using an RF shieldNMRin Biomedicine 33 1–11 Barberi E A, Gati J S, Rutt BKand Menon R S 2000A transmit-only/receive-only (TORO) RF system for high-field MRI/MRSapplications Magnetic Resonance in Medicine 43 284–9 Barfuss H, Fischer H, Hentschel D, Ladebeck R, Oppelt A, Wittig R, DuerrWand Oppelt R 1990 In vivo magnetic resonance imaging and spectroscopy of humans with a 4 T whole-body magnetNMRin Biomedicine 3 31–45 Barisano G, Sepehrband F,MaS, Jann K, Cabeen R, WangDJ, Toga AWand LawM2019 Clinical 7 T MRI: are we there yet?A review about magnetic resonance imaging at ultra-high field BJR 91 1–15 Beaumont J, Gambarota G, Saint-Jalmes H, Acosta O, Ferré J-C, Raniga P and Fripp J 2020 High-resolution multi-T1–weighted contrast and T1 mapping with low B1+sensitivity using the fluid and white matter suppression (FLAWS) sequence at 7T Magnetic Resonance in Medicine 85 1364–78 Beck B L, Jenkins KA, Rocca J R and Fitzsimmons J R 2004 Tissue-equivalent phantoms for high frequencies Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 20B 30–3 Berrington A, Považan M, MirfinC, Bawden S, Park YW, MarshDC, Bowtell R and Gowland P A 2021 Calibration-free regional RF shims forMRS Magnetic Resonance in Medicine 86 611–624 Boada F, Shepherd T, Rosenkrantz A, Sigmund E E, Fütterer J, Chandarana H, Hagiwara M, Rusinek H, Mikheev A, Bruno M, Geppert C, Glielmi C, Pfeuffer J et al 2013 Parallel transmission and its clinical implementation: enabling new clinical imaging paradigms FLASH 7 104–110 Bomsdorf H, Helzel T, Kunz D, Röschmann P, TschendelOand Wieland J 1988 Spectroscopy and imaging with a 4 Tesla whole-bodyMR systemNMRin Biomedicine 1 151–8 Bottomley P A and Andrew E R 1978 RF magnetic field penetration, phase shift and power dissipation in biological tissue: implications for NMRimaging Physics in Medicine&Biology 23 630–43 BoulantNand HoultDI 2012 High tip angle approximation based on a modified bloch-riccati equation Magnetic Resonance in Medicine 67 339–43 25 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al Boulant N,WuX, Adriany G, Schmitter S,UğurbilKand Van de Moortele P-F 2016 Direct control of the temperature rise in parallel transmission by means of temperature virtual observation points: simulations at 10.5 Tesla Magnetic Resonance in Medicine 75 249–56 Boulant N, Gras V, Amadon A, Luong M, FerrandGand VignaudA 2018 Workflow proposal for defining SAR safety margins in parallel transmission International Society for Magnetic Resonance in Medicine (Paris, France, 06/2018 pp 0295) Boyd S P and Vandenberghe L 2004 Convex Optimization. (Cambridge, New York: Cambridge University Press) BrinkWM, GulaniVand Webb AG2015 Clinical applications of dual-channel transmit MRI: a review Journal of Magnetic Resonance Imaging 42 855–69 BrunnerDO,De Zanche N, Froehlich J, BaumannDand PruessmannKP 2007 A symmetrically fed microstrip coil array for 7T International Society for Magnetic Resonance in Medicine (Berlin, Germany) p 448 BrunnerDO,De Zanche N, Fröhlich J, Paska J and Pruessmann KP 2009 Travelling-wave nuclear magnetic resonance Nature 457 994–8 Cabot E, Lloyd T, Christ A, Kainz W, Douglas M, Stenzel G, Wedan S and KusterN2013 Evaluation of the RF heating of a generic deep brain stimulator exposed in 1.5 T magnetic resonance scanners Bioelectromagnetics 34 104–13 Carluccio G, Akgun C, Vaughan J T and Collins C2021 Temperature-based MRI safety simulations with a limited number of tissues Magnetic Resononance in Medicine 86 543–50 Chen G, Zhang B, CloosMA, SodicksonDKand WigginsGC2018 A highly decoupled transmit–receive array design with triangular elements at 7T Magnetic Resonance in Medicine 80 2267–74 Christ A, Kainz W, Hahn EG, Honegger K, Zefferer M, Neufeld E, Rascher W, Janka R, Bautz W, Chen J et al 2010 The virtual family— development of surface-based anatomical models of two adults and two children for dosimetric simulations Physics in Medicine& Biology 55 N23–38 Chu SC, Gras V, McElhinney P, BoulantNand Gundamony S 2022 Design and optimization of transmit arrays for MRI at 11.7T International Society for Magnetic Resonance in Medicine (London, United Kingdom) p 0706 Chu X, Yang X, Liu Y, Sabate J and Zhu Y 2009 Ultra-low output impedance RF power amplifier for parallel excitation Magnetic Resonance in Medicine 61 952–61 Clément J, Gruetter R and IpekÖ2019 A combined 32-channel receive-Loops/8-channel transmit-dipoles coil array for whole-brainMR imaging at 7T Magnetic Resonance in Medicine 82 1229–41 Clément JD, Gruetter R and IpekÖ2019 A human cerebral and cerebellar 8-channel transceive RF dipole coil array at 7T Magnetic Resonance in Medicine 81 1447–58 CloosMA, Boulant N, Luong M, Ferrand G, Giacomini E, Le BihanDand Amadon A 2012 kT-points: short three-dimensional tailored RF pulses for flip-angle homogenization over an extended volume Magnetic Resonance in Medicine 67 72–80 CollinsCMand SmithMB 2001 Signal-to-noise ratio and absorbed power as functions of main magnetic field strength, and definition of 90° RF pulse for the head in the birdcage coil Magnetic Resonance in Medicine 45 684–91 Connell I ROand Menon R S 2019 Shape optimization of an electric dipole array for 7 Tesla neuroimaging IEEE Trans. Med. Imaging 38 2177–87 Davids M, Schad L R, Wald L L and Guérin B 2016 Fast three-dimensional inner volume excitations using parallel transmission and optimized K-space trajectories Magnetic Resonance in Medicine 76 1170–82 Decorps M, Blondet P, Reutenauer H, Albrand J P and Remy C1985 An inductively coupled, series-tunedNMRprobe Journal of Magnetic Resonance 65 100–9 de Greef M, Ipek O, Raaijmakers A J E, Crezee J and van den BergCA T 2013 Specific absorption rate intersubject variability in 7T parallel transmit MRI of the head Magnetic Resonance in Medicine 69 1476–1485 Delfino J 2014 Criteria for Significant Risk Investigations of Magnetic Resonance Diagnostic Devices (Guidance for Industry and Food and Drug Administration Staff). (Rockville, MD, USA: Food and Drug Administration) Duan Q, Nair G, Gudino N, de Zwart J A, van Gelderen P, Murphy-Boesch J, ReichDS, Duyn JHand MerkleH2015 A 7T spine array based on electric dipole transmitters Magnetic Resonance in Medicine 74 1189–97 Duyn JH, Yang Y, Frank J A and van der Veen JW1998 Simple correction method for k-space trajectory deviations in MRI Journal of Magnetic Resonance 132 150–3 Eberhardt B, Poser BA, ShahNJ and Felder J 2020 Application of evolution strategies to the design of SAR efficient parallel transmit multispoke pulses for ultra-high field MRI IEEE Transactions on Medical Imaging 39 4225–36 Eberhardt B, Poser BA, ShahNJ and Felder J 2022 B1 field map synthesis with generative deep learning used in the design of paralleltransmit RF pulses for ultra-high field MRI Zeitschrift für Medizinische Physik 32 334–345 Ehses P, Fidler F, Nordbeck P, Pracht ED, Warmuth M, Jakob PMand BauerWR 2008 MRI thermometry: fast mapping of RF-induced heating along conductive wires Magnetic Resonance in Medicine 60 457–61 EichfelderGand GebhardtM2011 Local specific absorption rate control for parallel transmission by virtual observation points Magnetic Resonance in Medicne 66 1468–76 Elabyad IA, Terekhov M, Lohr D, StefanescuMR, Baltes S and Schreiber LM2020 Anovel mono-surface antisymmetric 8Tx/16Rx coil array for parallel transmit cardiac MRI in pigs at 7T Scientific Reports 10 1–183117 ErtürkMA et al 2017a Toward imaging the body at 10.5 Tesla Magnetic Resonance in Medicine 77 434–43 ErturkMA, LiX, Van de Moortele P-F, UgurbilKand MetzgerGJ 2019 Evolution ofUHFbody imaging in the human torso at 7T: technology, applications, and future directions Topics MRI 28 101–24 ErtürkMA, Raaijmakers A J E, Adriany G,UğurbilKand MetzgerGJ 2017b A 16-channel combined loop-dipole transceiver array for 7 Tesla body MRI Magnetic Resonance in Medicine 77 884–94 Eryaman Y, Akin B and Atalar E 2011 Reduction of implant RF heating through modification of transmit coil electric field Magnetic. Resonance in. Medicine. 65 1305–13 Eryaman Y, Guerin B, Akgun C, Herraiz J I, Martin A, Torrado-Carvajal A, Malpica N, Hernandez-Tamamos J A, Schiavi E, Adalsteinsson E, Wald L L et al 2015 Parallel transmit pulse design for patients with deep brain stimulation implants Magnetic. Resonance in. Medicine. 73 1896–903 Eryaman Y, Turk E A, Oto C, AlginOand Atalar E 2013 Reduction of RF heating with a dual-drive birdcage coil Magnetic. Resonance in. Medicine. 69 845–52 Eryaman Y, Guerin B, Kosior R, Adalsteinsson E and Wald L L 2013 Combined Loop+Dipole Arrays for 7 T brain imgaing Int. Society for Magnetic Resonance in Medicine. ISMag. Reson. Med. (Salt Lake City, UT, USA) p 0393 Etezadi-Amoli M, Stang P P, Kerr A B, Pauly JMand ScottGC2015 Controlling radiofrequency-induced currents in guidewires using parallel transmit Magnetic. Resonance in. Medicine. 74 1790–802 2017 FDA clears first 7T magnetic resonance imaging deviceFDA News Release fda.gov 2020 FDA Clears Most Powerful Clinical MRI Medgadget.com 26 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al FeinbergDA et al 2021 Design and development of a next-generation 7T human brain scanner with high-performance gradient coil and dense RF arrays International Society for Magnetic Resonance in Medicin (Virtual pp 0562) e. FeinbergDA, Hoenninger JC, Crooks L E, Kaufman L, Watts JCand ArakawaM1985 Inner volumeMRimaging: technical concepts and their application Radiology 156 743–7 Feng K, HollingsworthNA, McDougallMP and Wright SM2012 A 64-channel transmitter for investigating parallel transmit MRI IEEE Transactions on Biomedical Engineering 59 2152–60 Fiedler TM, LaddME and BitzAK2018 SAR simulations&safety NeuroImage 168 33–58 Fiedler TM, Orzada S, Flöser M, Rietsch SHG, Schmidt S, Stelter JK, Wittrich M, QuickHH, Bitz AKand LaddME 2021 Performance and safety assessment of an integrated transmit array for body imaging at 7 T under consideration of specific absorption rate, tissue temperature, and thermal doseNMRin Biomedicine 35 1–17 GadianDGand Robinson FNH1979 Radiofrequency losses inNMRexperiments on electrically conducting samples Journal of Magnetic Resonance 34 449–55 Geldschläger O, Bosch D, Glaser S and Henning A2021 Local excitation universal parallel transmit pulses at 9.4T Magnetic Resonance in Medicine. 86 2589–693 GilbertKM, Belliveau J-G, CurtisA T, Gati J S, Klassen LMand Menon R S 2012 Aconformal transceive array for 7 T neuroimaging Magnetic Resonance in Medicine 67 1487–96 GilbertKM, CurtisA T, Gati J S, Martyn Klassen L, Villemaire L E and Menon R S 2010 Transmit/receive radiofrequency coil with individually shielded elements: transceive coil with individually shielded elements Magnetic Resonance in Medicine. 64 1640–51 GilbertKM, CurtisA T, Gati J S, Klassen LMand Menon R S 2011 A radiofrequency coil to facilitate B1+shimming and parallel imaging acceleration in three dimensions at 7TNMRin Biomedicine 24 815–23 GloverGH, HayesCE, PelcNJ, EdelsteinWA, MuellerOM, HartHR, HardyCJ,O’DonnellMand BarberWD1985 Comparison of linear and circular polarization for magnetic resonance imaging Journal of Magnetic Resonance 64 255–70 Godinez F, Scott G, Padormo F, Hajnal JVand Malik S J 2019 Safe guidewire visualization using the modes of a pTx transmit arrayMR system Magnetic Resonance in Medicine. 83 2343–2355 Godinez F, Tomi-Tricot R, Delcey M, Williams S E, Mooiweer R, Quesson B, Razavi R, Hajnal JVand Malik S J 2021 Interventional cardiac MRI using an add-on parallel transmitMr system: in vivo experience in sheep Magnetic Resonance in Medicine. 86 3360–72 Graessl A, Renz W, Hezel F, DieringerMA, Winter L, Oezerdem C, Rieger J, Kellman P, Santoro D, Lindel T, Frauenrath T, Pfeiffer H, Niendor T et al 2013 Modular 32-channel transceiver coil array for cardiac MRI at 7.0T Magnetic Resonance in Medicine. 72 276–90 Gräßl A, Winter L, Thalhammer C, Renz W, Kellman P, Martin C, von Knobelsdorff-Brenkenhoff F, Tkachenko V, Schulz-Menger J and Niendorf T 2013 Design, evaluation and application of an eight channel transmit/receive coil array for cardiac MRI at 7.0T European . J.Journal of Radiology. 82 752–9 Graesslin I, Homann H, Biederer S, Börnert P, Nehrke K, Vernickel P, Mens G, Harvey P and KatscherU2012 A specific absorption rate prediction concept for parallel transmission Mr Magnetic Resonance in Medicine. 68 1664–74 Gras V, Boland M, Vignaud A, Ferrand G, Amadon A, Mauconduit F, Le Bihan D, Stöcker T and BoulantN2017a Homogeneous nonselective and slice-selective parallel-transmit excitations at 7 Tesla with universal pulses: a validation study on two commercial RF coils PLoS One 12 e0183562 Gras V, Pracht ED, Mauconduit F, Le Bihan D, Stöcker T and BoulantN2019 Robust nonadiabatic T 2 preparation using universal paralleltransmit kT-point pulses for 3D FLAIR imaging at 7 T Magnetic Resonance in Medicine 81 3202–8 Gras V, Vignaud A, Amadon A, Le BihanDand BoulantN2017 Universal Pulses: a new concept for calibration-free parallel transmission Magnetic Resonance in Medicine 77 635–43 Grissom W, Yip C, Zhang Z, StengerVA, Fessler J A and NollDC2006 Spatial domain method for the design of RF pulses in multicoil parallel excitation Magnetic Resonance in Medicine 56 620–9 GrissomWA, Yip C-Y, Wright SM, Fessler J Aand NollDC2008 Additive angle method for fast large-tip-angle RF pulse design in parallel excitation Magnetic Resonance in Medicine 59 779–87 GriswoldMA, Jakob PM, Heidemann RM, Nittka M, Jellus V, Wang J, Kiefer B and HaaseA 2002 Generalized autocalibrating partially parallel acquisitions (GRAPPA) Magnetic Resonance in Medicine 47 1202–10 Gruber B, Froeling M, Leiner T and KlompDWJ 2018 RF coils: a practical guide for nonphysicists: RF coils Journal of Magnetic Resonance Imaging 48 590–604 Gruber B, Stockmann J P, Mareyam A, Keil B, Ghotra A, Feinberg, David A and Wald L L 2021 A 128-channel head coil array for cortical imaging at 7 Tesla International Society for Magnetic Resonance in Medicine. Virtual p 0176 GudinoNand GriswoldMA2013 Multi-turn transmit coil to increase B1 efficiency in current source amplification: increased B1 efficiency by multi-turn transmit coil Magnetic Resonance in Medicine 69 1180–5 Gudino N, Zwart J A and Duyn JH2020 Eight-channel parallel transmit-receive system for 7 T MRI with optically controlled and monitored on-coil current-mode RF amplifiers Magnetic Resonance in Medicine 84 3494–501 Guérin B, Gebhardt M, Cauley S, Adalsteinsson E and Wald L L 2014 Local Specific absorption rate (SAR), global SAR, transmitter power, and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design Magnetic Resonance in Medicine 71 1446–57 Guérin B, IaconoMI, Davids M, Dougherty D, Angelone LMand Wald L L 2019 The ‘virtual DBS population’: five realistic computational models of deep brain stimulation patients for electromagneticMRsafety studies Phys. Med. Biol. 64 035021 HayesCE, EdelsteinWA, Schenck J F, MuellerOMand EashM1985 An efficient, highly homogeneous radiofrequency coil for whole-body NMRimaging at 1.5 T Journal of Magnetic Resonance 63 622–28 HayesCE, HattesNand Roemer P B 1991 Volume imaging withMRphased arrays Magnetic Resonance in Medicine 18 309–19 Heilman J A, RiffeMJ, HeidOand GriswoldMA 2007 High power, high efficiency on-coil current-mode amplifier for parallel transmission arrays International Society for Magnetic Resonance in Medicine. ISMag. Reson. Med. (Berlin, Germany) p 171 Hennig J E, Naureth A and FriedburgH1986 RARE imaging: a fast imaging method for clinical Mr Magnetic Resonance in Medicine 3 823–33 Herrler J, Liebig P, Gumbrecht R, Ritter D, Schmitter S, Maier A, Schmidt M, Uder M, Doerfler A and Nagel AM2021a Fast onlinecustomized (FOCUS) parallel transmission pulses: a combination of universal pulses and individual cptimization Magnetic Resonance in Medicine 85 3140–53 Herrler J, Williams SN, Liebig P, Shajan G, Meixner C, Maier A, Doerfler A, PorterDA and Nagel AM2021b Evaluating universal and fast online customized pulses for parallel transmission using two different RF coils International Society for Magnetic Resonance in Medicine. (Virtual) pp 3950 Hoffmann J, Henning A, Giapitzakis IA, Scheffler K, Shajan G, Pohmann R and AvdievichNI 2016 Safety testing and operational procedures for self-developed radiofrequency coilsNMRin Biomedicine 29 1131–44 27 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al Hoffmann J, Shajan G, SchefflerKand Pohmann R 2014 Numerical and experimental evaluation of RF shimming in the human brain at 9.4 T using a dual-row transmit array Magnetic Resonance Materials in Physics, Biology and Medicine 27 373–86 Hong S-M, Park JH,WooM-K, Kim Y-B and Cho Z-H 2014 New design concept of monopole antenna array forUHF7T MRI Magnetic Resonance in Medicine 71 1944–52 HoultDI 2000 Sensitivity and power deposition in a high-field imaging experiment Journal of Magnetic Resonance Imagin 12 46–67 HoultDI, Kolansky G, KripiakevichDand King S B 2004 TheNMRmulti-transmit phased array: a cartesian feedback approach Journal of Magnetic Resonance 171 64–70 HoultDI and Richards R E 1976 The signal-to-noise ratio of the nuclear magnetic resonance experiment Journal of Magnetic Resonance 24 71–85 Hoyos-Idrobo A, Weiss P, Massire A, AmadonA and BoulantN2013 On variant strategies to solve the magnitude least squares optimization problem in parallel transmission pulse design and under strict SAR and power constraints IEEE Transactions on Medical Imaging 33 739–48 Ianni JD, Cao Z and GrissomWA 2018 Machine learning RF shimming: prediction by iteratively projected ridge regression Magnetic Resonance in Medicine 80 1871–81 Ibrahim T S 2004 A numerical analysis of radio-frequency power requirements in magnetic resonance imaging experiment IEEE Transactions on Microwave Theory and Techniques 52 1999–2003 Ibrahim T S, Lee R, Abduljalil AM, Baertlein BA and Robitaille P-M L 2001a Dielectric resonances and B1 field inhomogeneity inUHFMRI: computational analysis and experimental findings Magnetic Resonance Imaging 19 219–26 Ibrahim T S, Lee R, Baertlein B A, Abduljalil AM, ZhuHand Robitaille P-M L 2001b Effect of RF coil excitation on field inhomogeneity at ultra high fields: a field optimizedTEMresonator Magnetic Resonance Imaging 19 1339–47 Ibrahim T S, Lee R, Baertlein B A, Kangarlu A and Robitaille P-M L 2000 Application of finite difference time domain method for the design of birdcage RF head coils using multi-port excitations Magnetic Resonance Imaging 18 733–42 Ibrahim T S and Tang L 2007 Insight into RF power requirements and B1 field homogeneity for human MRI via rigorous FDTD approach Journal of Magnetic Resonance Imaging 25 1235–47 IEC 60601-2-33 2022 Medical electrical equipment – Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis International Electrotechnical Commission 306 Ipek Ö, Raaijmakers A J, Lagendijk J J, Luijten P R and van den BergCA T 2014 Intersubject local SAR variation for 7T prostateMRimaging with an eight-channel single-side adapted dipole antenna array Magnetic Resonance in Medicine71 4 1559-1567 Ishihara Y, Calderon A, Watanabe H, Okamoto K, Suzuki Y, Kuroda Kand Suzuki Y 1995 AprJinecise and fast temperature mapping using water proton chemical shift Magnetic Resonance in Medicine 34 814–23 Jin J, Weber E, Destruel A,O’Brien K, Henin B, EngstromCand Crozier S 2017 An open 8-channel parallel transmission coil for static and dynamic 7T MRI of the knee and ankle joints at multiple postures Mag. Reson. Med. 79 1804–1816 Katscher U, Bornert P and van den Brink J S 2004 Theoretical and numerical aspects of transmit SENSE IEEE Transactions on Medical Imaging 23 520–5 Katscher U, Börnert P, LeusslerCand van den Brink J S 2003 Transmit SENSE Magnetic Resonance in Medicine 49 144–50 Kazemivalipour E, Sadeghi-Tarakameh A and Atalar E 2021 Eigenmode analysis of the scattering matrix for the design of MRI transmit array coils Mag. Reson. Med. 85 1727–41 Khaneja N, Reiss T, Kehlet C, Schulte-Herbrüggen T and Glaser S J 2005 Optimal control of coupled spin dynamics: design ofNMRpulse sequences by gradient ascent algorithms Journal Magnetic Resonance 172 296–305 Kokubunji TN, Soka T T, Kashiwa YM, Akishima E Y and KatakuraK1994 RF Probe for MRI. 5,489,847 https://patents.google.com/ patent/US5489847A/en 8475489 Kopanoglu E, DenizCM, ErturkMA and Wise RG2020 Specific absorption rate implications of within-scan patient head motion for ultrahigh field MRI Magnetic Resonance in Medicine 84 2724–38 KozlovMand Turner R 2009 Fast MRI coil analysis based on 3D electromagnetic and RF circuit co-simulation Journal of Magnetic Resonance 200 147–52 KozlovMand Turner R 2010 Effects of simplifying RF coil 3DEMsimulation models on power balance and SAR International Society for Magnetic Resonance in Medicine (Stockholm, Sweden pp 1445) p 1445 Kozlov M, Weiskopf N, MöllerHE and ShajanG2018 Reverse engineering of a 7T 16-channel dual-row transmit array coil International Society for Magnetic Resonance in Medicine (Paris, France) p 4412 Kraff O, Bitz AK, Kruszona S, Orzada S, Schaefer LC, Theysohn JM, Maderwald S, LaddME and QuickHH2009 An eight-channel phased array RF coil for spineMRimaging at 7 T Investigative Radiolology 44 734–40 KraffOand QuickHH2017 7T: physics, safety, and potential clinical applications: 7T: physics, safety, applications Journal Magnetic Resonance Imaging 46 1573–89 Kuehne A, Goluch S, Waxmann P, Seifert F, Ittermann B, Moser E and Laistler E 2015 Power balance and loss mechanism analysis in RF transmit coil arrays: transmit array loss analysis Magnetic Resonance in Medicine 74 1165–76 Kumar A, EdelsteinWAand Bottomley P A 2009 Noise figure limits for circular loopMRcoils Magnetic Resonance in Medicine 61 1201–9 KurpadKN, Wright SMand Boskamp E B 2006 RF current element design for independent control of current amplitude and phase in transmit phased arrays Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 29B 75–83 Lakshmanan K, Cloos M, Brown R, Lattanzi R, SodicksonDKand WigginsGC2020 The ‘Loopole’ antenna: a hybrid coil combining loop and electric dipole properties for ultra-high-field MRI Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 2020 1–9 Lakshmanan K, CloosMA, Lattanzi R, SodicksonDK, NovikovDS and WigginsGC2014 The circular dipole International Society for Magnetic Resonance in Medicine (Milan, Italy pp 0315) Lanz T, Müller M, Barnes H, Neubauer S and Schneider J E 2010 A high-throughput eight-channel probe head for murine MRI at 9.4 T Magnetic Resonance in Medicine 64 80–7 Lattanzi R, GrantAK, Polimeni J R, OhligerMA, WigginsGC, Wald L L and SodicksonDK2010 Performance evaluation of a 32-element head array with respect to the ultimate intrinsic SNRNMRin Biomedicine 23 142–51 Le Garrec M, Gras V, Hang M-F, Ferrand G, LuongMand BoulantN2017 Probabilistic analysis of the specific absorption rate intersubject variability safety factor in parallel transmission MRI Magnetic Resonance in Medicine 78 1217-1223 Lattanzi R and SodicksonDK2012 Ideal current patterns yielding optimal signal-to-noise ratio and specific absorption rate in magnetic resonance imaging: computational methods and physical insights Magnetic Resonance in Medicine 68 286–304 Le Ster C, Mauconduit F, Massire A, BoulantNand GrasV2022 Standardized universal pulse: a fast RF calibration approach to improve flip angle accuracy in parallel transmission Magnetic Resonance in Medicine 87 2839–50 28 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al Le Ster C, Mauconduit F, Mirkes C, Bottlaender M, Boumezbeur F, Djemai B, Vignaud Aand BoulantN2021 RF heating measurement usingMRthermometry and field monitoring: methodological considerations and first in vivo results Magnetic Resonance in Medicine 85 1282–93 Le Ster Cet al 2019 Comparison of SMS-EPI and 3D-EPI at 7T in an fMRI localizer study with matched spatiotemporal resolution and homogenized excitation profiles PLoS One 14 e0225286 Lee J, Gebhardt M, Wald L L and Adalsteinsson E 2012 Local SAR in parallel transmission pulse design Magnetic Resonance in Medicine 67 1566–78 Lee R F, Giaquinto ROand Hardy CJ 2002 Coupling and decoupling theory and its application to the MRI phased array Magnetic Resonance in Medicine 48 203–13 Lee R F, Hardy CJ, SodicksonDKand Bottomley P A 2004 Lumped-element planar strip array (LPSA) for parallel MRI Magnetic Resonance in Medicine 51 172–83 Lee R F, Westgate CR, Weiss RG, NewmanDCand Bottomley P A 2001 Planar strip array (PSA) for MRI Magnetic Resonance in Medicine 45 673–83 Lee W, Cloos M, SodicksonDand WigginsG2013 Parallel transceiver array design using the modified folded dipole for 7T body applications International Society for Magnetic Resonance in Medicine (Salt Lake City, UT, USA pp 0292) Lian J and Roemer P B 1997 MRI RF Coil. 5,804,969 https://patents.google.com/patent/US5804969A/en9695804 Luo T, NollDC, Fessler J A and Nielsen J-F 2020 Joint design of RF and gradient waveforms via auto-differentiation for 3D tailored excitation in MRI IEEE Transactions on Medical Imaging 40 3305–3314 MajewskiK2021 Simultaneous optimization of radio frequency and gradient waveforms with exact hessians and slew rate constraints applied to k T -points excitation Journal of Magnetic Resonance 326 106941 MajewskiKand RitterD2015 First and second order derivatives for optimizing parallel RF excitation waveforms Journal of Magnetic Resonance 258 65–80 Malik S J, Beqiri A, Padormo F and Hajnal JV2015 Direct signal control of the steady-state response of 3D-FSE sequences Magnetic Resonance in Medicine 73 951–63 Malik S J, Keihaninejad S, Hammers A and Hajnal JV2012 Tailored excitation in 3D with spiral nonselective (SPINS) RF pulses Magnetic Resonance in Medicine 67 1303–15 Mao W, SmithMB and CollinsCM2006 Exploring the limits of RF shimming for high-field MRI of the human head Magnetic Resonance in Medicine 56 918–22 Mareyam A, Kirsch J E, Chang Y, MadanGand Wald L L 2020 A 64-Channel 7T array coil for accelerated brain MRI International Society for Magnetic Resonance in Medicine (Virtual p 0764, 08/2020) Marques J P, Kober T, Krueger G, van der Zwaag W, Van de Moortele P-F and Gruetter R 2010 MP2RAGE, a self bias-field corrected sequence for improved segmentation and T1-mapping at high field NeuroImage 49 1271–81 Massire A, Mauconduit F, Lapert M, Naudin M, Guillevin R, Vignaud A and BoulantN2022 PASTEUR: package of anatomical sequences using parallel transmission universal pulses now available forMAGNETOMterra FLASH 80 2–13 Massire A, Taso M, Besson P, Guye M, Ranjeva J-P and CallotV2016 High-resolution multi-parametric quantitative magnetic resonance imaging of the human cervical spinal cord at 7T NeuroImage 143 58–69 Mattei E, Triventi M, Calcagnini G, Censi F, Kainz W, BassenHI and Bartolini P 2007 Temperature and SAR measurement errors in the evaluation of metallic linear structures heating during MRI using fluoroptic® probes Physics in Medicine&Biology 52 1633–46 MayMW, Hansen S-L JD, Mahmutovic M, Scholz A, Kutscha N, Guerin B, Stockmann J P, Barry R L, Kazemivalipour E, Gumbrecht R, Kimmlingen R, Adriany M, Chang Y, Traintafyllou C, Knake S, Wald L L, Keil B et al 2022 A patient-friendly 16-channel Transmit/ 64-channel receive coil array for combined head–neck MRI at 7 Tesla Mag. Reson. Med. mrm.29288 88 1419–1433 McElcheranCE, Golestanirad L, IaconoMI, Wei P-S, Yang B, Anderson KJ T, BonmassarGand Graham S J 2019 Numerical simulations of realistic lead trajectories and an experimental verification support the efficacy of parallel radiofrequency transmission to reduce heating of deep brain stimulation implants during MRI Scientific Reports 9 1–142124 Meliadò E F, Sbrizzi A, van den BergCAT, Steensma B R, Luijten P R and Raaijmakers A J E 2020a Conditional safety margins for less conservative peak local SAR assessment: a probabilistic approach Magnetic Resonance in Medicine 84 3379–95 MetzgerGJ, Snyder C, Akgun C, Vaughan T,UğurbilKand Van de Moortele P-F 2008 Local B1+Shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements Magnetic Resonance in Medicine 59 396–409 Local B1+Shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements Meliadò E F, Raaijmakers A J E, Sbrizzi A, Steensma B R, Maspero M, SavenijeMHF, Luijten P R and van den BergCA T 2020b A deep learning method for image-based subject-specific local SAR assessment Magnetic Resonance in Medicine 83 695–711 Mooiweer R, Sbrizzi A, Raaijmakers A J E, van den BergCA T, Luijten P R and HoogduinH2018 Phase matched RF pulse design for imaging a reduced field of excitation with a fast TSE acquisition Magnetic Resonance Imaging 51 128–36 Mugler J P 2014 Optimized three-dimensional fast-spin-echo MRI Journal of Magnetic Resonance Imaging 39 745–67 Mugler J P and Brookeman J R 1990 Three-dimensional magnetization-prepared rapid gradient-echo imaging (3DMPRAGE) Magnetic Resonance in Medicine 15 152–7 Murphy-Boesch J and Koretsky A P 1983 An in vivoNMRprobe circuit for improved sensitivity Journal of Magnetic Resonance 54 526–32 NoetscherGM, Serano P, WartmanWA, FujimotoKand Makarov SN2021 Visible human project® female surface based computational phantom (nelly) for radio-frequency safety evaluation in MRI coils PLoSONE16 e0260922 Nowogrodzki A2018 The world’s strongest MRI machines are pushing human imaging to new limits Nature56324–6 OECDMagnetic resonance imaging (MRI) units (indicator) 09-12-2022 https://doi.org/10.1787/1a72e7d1-en Oezerdem C, Winter L, Graessl A, Paul K, Els A, Weinberger O, Rieger J, Kuehne A, Dieringer M, Hezel F, Voit D, Frahm J, Niendorf T et al 2016 16-channel bow tie antenna transceiver array for cardiacMRat 7.0 Tesla Magnetic Resonance in Medicine 75 2553–65 OhligerMA, GrantAKand SodicksonDK2003 Ultimate intrinsic signal-to-noise ratio for parallel MRI: electromagnetic field considerations Magnetic Resonance in Medicine 50 1018–30 OngKC,Wen H, Chesnick AS, Duewell S, Jaffer FA and Balaban R S 1995 Radiofrequency shielding of surface coils at 4.0T Journal of Magnetic Resonance Imaging 5 773–7 Orzada S, BahrA and Bolz T 2008 A novel 7 T microstrip element using meanders to enhance decoupling International Society for Magnetic Resonance in Medicine (Toronto, Canada) p 2979 Orzada S, Bitz AK, Schäfer LC, Ladd SC, LaddME and Maderwald S 2011 Open design eight-channel transmit/receive coil for highresolution and real-time ankle imaging at 7 T Medical Physics 38 1162–7 29 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al Orzada S, Fiedler TM, BitzAK, LaddME and QuickHH2021 Local SAR compression with overestimation control to reduce maximum relative SAR overestimation and improve multi-channel RF array performance Magnetic Resonance Materials, Biology and Medicine 34 153–63 Orzada S et al 2019A 32-channel parallel transmit system add-on for 7T MRI PLoSONE14 e0222452 Padormo F, Beqiri A, Hajnal JVand Malik S J 2016 Parallel transmission for ultrahigh-field imagingNMRin Biomedicine 29 1145–61 Paez A, GuCand Cao Z 2021 Robust RF shimming and small-tip-angle multispoke pulse design with finite-difference regularization Magnetic Resonance in Medicine 86 1472–81 Paterson G, McElhinney P, PhilliastidesMGand ShajanG2020 A tight-fit 8-channel transceiver array for simultaneous EEG-fMRI at 7-Tesla International Society for Magnetic Resonance in Medicine (Virtual pp 4034) Pauly JM, NishimuraDGand Macovski A 1989 A kSpace analysis of small-tip angle excitation Journal of Magnetic Resonance 81 43–56 Pauly JM, Le Roux P, NishimuraDGand Macovski A 1991 Parameter relations for the Shinnar-Le Roux selective excitation pulse design algorithm IEEE Transactions on Medical Imaging 10 53–65 Paška J, CloosMA and WigginsGC2018 Arigid, stand-off hybrid dipole, and birdcage coil array for 7 T body imaging Magnetic Resonance in Medicine 80 822–32 Pendse M, Stara R, Mehdi KhalighiMand Rutt B 2019 IMPULSE: a scalable algorithm for design of minimum specific absorption rate parallel transmit RF pulses Magnetic Resonance in Medicine 81 2808–22 PennesHH1948 Analysis of tissue and arterial blood temperatures in the resting human forearm Journal of Applied Physiology 85 93–122 PetersonDM, Beck B L, DuensingGR and Fitzsimmons J R 2003Common mode signal rejection methods for MRI: reduction of cable shield currents for high static magnetic field systems Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 19B 1–8 Pfaffenrot V, Brunheim S, Rietsch SHG, Koopmans P J, Ernst TM, Kraff O, Orzada S and QuickHH2018 An 8/15-channel Tx/Rx head neck RF coil combination with region-specificB1+shimming for whole-brain MRI focused on the cerebellum at 7T Magnetic Resonance in Medicine 80 1252–65 An 8/15-channel Tx/Rx head neck RF coil combination with region-specificB1+shimming for whole-brain MRI focused on the cerebellum at 7T Plumley A, Watkins L, Treder M, Liebig P, MurphyKand Kopanoglu E 2021 Rigid motion-resolved prediction using deep learning for realtime parallel-transmission pulse design Magnetic Resonance in Medicine 87 2254–70 Pohmann R, SpeckOand SchefflerK2016 Signal-to-noise ratio andMRtissue parameters in human brain imaging at 3, 7, and 9.4 Tesla using current receive coil arrays: SNR at 9.4T Magnetic Resonance in Medicine 75 801–9 PruessmannKP, Weiger M, ScheideggerMB and Boesiger P 1999 SENSE: sensitivity encoding for fast MRI Magnetic Resonance in Medicine 42 952–62 Raaijmakers AJ E, Ipek O, KlompDWJ, Possanzini C, Harvey P, Lagendijk J JWand van den BergCAT 2011 Design of a radiative surface coil array element at 7 T: the single-side adapted dipole antenna Magnetic Resonance in Medicine 66 1488–97 Raaijmakers AJ E, Luijten P R and van den Berg CAT 2016 Dipole antennas for ultrahigh-field body imaging: a comparison with loop coils NMRin Biomedicine 29 1122–30 Raaijmakers AJ E, Italiaander M, Voogt I J, Luijten P R, Hoogduin JM, KlompDWJ and van den BergCA T 2016 The fractionated dipole antenna: a new antenna for body imaging at 7 Tesla Magnetic Resonance in Medicine 75 1366–74 Rietsch SHG, Brunheim S, Orzada S, VoelkerMN, Maderwald S, Bitz AK, Gratz M, LaddME and QuickHH2019 Development and evaluation of a 16-channel receive-only RF coil to improve 7T ultra-high field body MRI with focus on the spine Magnetic Resonance in Medicine 82 796–810 Rietsch SHG, Orzada S, BitzAK, Gratz M, LaddME and QuickHH2018a Parallel transmit capability of various RF transmit elements and arrays at 7T MRI Magnetic Resonance in Medicine 79 1116–26 Rietsch SHG, Orzada S, Maderwald S, Brunheim S, Philips BWJ, Scheenen TWJ, LaddME and QuickHH2018b 7T ultra-high field body MRimaging with an 8-channel transmit/32-channel receive radiofrequency coil array Medical Physics 45 2978–90 Rietsch SHG, QuickHHand Orzada S 2015 Impact of different meander sizes on the RF transmit performance and coupling of microstrip line elements at 7 T: impact of different meander sizes on RF characteristics Medical Physics 42 4542–52 Rinck P A 2018 Magnetic Resonance in Medicine: A Critical Introduction (Germany: Books on DemandGmbH) 12th edn Robitaille P-M L, Abduljalil AMand Kangarlu A 2000 Ultra high resolution imaging of the human head at 8 Tesla: 2K×2K for Y2K Journal of Computer Assisted Tomography 24 2–8 Ultra high resolution imaging of the human head at 8 Tesla: 2K×2K for Y2K Robitaille P-M L, Abdulijalil AM, Kangarlu A, Zhang X, Yu Y, Burgess R, Bair S, Noa P, Yang L, Zhu H, Palmer B, Jiang Z, ChakeresDM, SpigosDet al 1998 Human magnetic resonance imaging at 8 TNMRin Biomedicine 11 263–5 Roemer P B, EdelsteinWA, HayesCE, Souza S P and MuellerOM1990 TheNMRphased array Magnetic Resonance in Medicine 16 192–225 Roschmann P KH1986 High-frequency coil system for a magnetic resonance imaging apparatus US4746866A Roschmann P KH1987 Radiofrequency penetration and absorption in the human body: limitations to high-field whole-body nuclear magnetic resonance imaging Medical Physics 14 922–31 Sadeghi-Tarakameh A, Adriany G, MetzgerGJ, Lagore R L, Jungst S, DelaBarre L, Van de Moortele P,Uğurbil K, Atalar E and Eryaman Y 2020 Improving radiofrequency power and specific absorption rate management with bumped transmit elements in ultra-high field MRI Magnetic Resonance in Medicine 84 3485–93 Saekho S, Yip C, NollDC, Boada F E and StengerVA 2005 Fast-kz Three-dimensional tailored radiofrequency pulse for reduced B1 inhomogeneity Magnetic Resonance in Medicine 55 719–24 Schneider J T, Kalayciyan R, Haas M, Herrmann S R, Ruhm W, Hennig J and Ullmann P 2013 Inner-volume imaging in vivo using threedimensional parallel spatially selective excitation Magnetic Resonance in Medicine 69 1367–78 ScottGC, Stang P, Kerr A B and Pauly JM2008 General signal vector decoupling for transmit arrays International Society for Magnetic Resonance in Medicine (Toronto, Canada pp 1146) SeeberDA, Jevtic J and MenonA 2004 Floating shield current suppression trap Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 21B 26–31 Sengupta S, Roebroeck A, KemperVG, Poser BA, Zimmermann J, Goebel R and AdrianyG2016 Aspecialized multi-transmit head coil for high resolution fMRI of the human visual cortex at 7T PLoSONE11 e0165418 Setsompop K, Wald L L, Alagappan V, Gagoski B, Hebrank F, Fontius U, Schmitt F and Adalsteinsson E 2006 Parallel RF transmission with eight channels at 3 Tesla Magnetic Resonance in Medicine 56 1163–71 Setsompop K, Wald L L, Alagappan V, Gagoski BA and Adalsteinsson E 2008 Magnitude least squares optimization for parallel radio frequency excitation design demonstrated at 7 Tesla with eight channels Magnetic Resonance in Medicine 59 908–15 Shajan G, Hoffmann J, Budde J, Adriany G,UğurbilKand Pohmann R 2011 Design and evaluation of an RF front-end for 9.4 T human MRI Magnetic Resonance in Medicine 66 594–602 30 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al Shajan G, Kozlov M, Hoffmann J, Turner R, SchefflerKand Pohmann R 2014 A16-channel dual-row transmit array in combination with a 31-element receive array for human brain imaging at 9.4 T Magnetic Resonance in Medicine 71 870–9 Shajan G, Müller R, McElhinney P, Williams SN, Groß-Weege N, Weiskopf N, MöllerHE and FeinbergD2021 A 16-channel transmit 96- channel receive head coil for NexGen 7T scanner International Society for Magnetic Resonance in Medicine (Virtual pp 0182) Shin D, Kim Y,Oh C, An H, Park J, Kim J and Lee J 2021 Deep reinforcement learning-designed radiofrequency waveform in MRI Nature Machine Intelligence 3 985–94 Shrivastava D, Hanson T, Kulesa J, Tian J, AdrianyGand Vaughan J T 2011 Radiofrequency heating in porcine models with a ‘large’ 32 cm internal diameter, 7 T (296MHz) head coil: in vivo RF heating at 7 T Magnetic Resonance in Medicine 66 255–63 Sigmund E E, SueroGA,HuC, McGorty K, SodicksonDK, WigginsGCand Helpern J A2012 High-resolution human cervical spinal cord imaging at 7 TNMRin Biomedicine 25 891–9 SnyderCJ, DelaBarre L, MetzgerGJ, van de Moortele P-F, Akgun C,UğurbilKand Vaughan J T 2009 Initial results of cardiac imaging at 7 Tesla Magnetic Resonance in Medicine 61 517–24 SnyderCJ, DelaBarre L, Moeller S, Tian J, Akgun C, Van de Moortele P-F, Bolan P J,Uğurbil K, Vaughan J T and MetzgerGJ 2012 Comparison between eight- and sixteen-channel TEMtransceive arrays for body imaging at 7 T Magnetic Resonance in Medicine 67 954–64 SodicksonDKand ManningWJ 1997 Simultaneous acquisition of apatial harmonics (SMASH): fast imaging with radiofrequency coil arrays Magnetic Resonance in Medicine 38 591–603 Solomakha G, Leeuwen C, van, Raaijmakers A, Simovski C, Popugaev A, Abdeddaim R, Melchakova I and Glybovski S 2019 The dual-mode dipole: a new array element for 7T body imaging with reduced SAR Magnetic Resonance Medicine 81 1459–69 Steensma BD, Vivian Obando Andrade A, KlompDWJ, van den BergCA T, Luijten P R and Raaijmakers A J E 2016 Body imaging at 7 tesla with much lower SAR levels: an introduction of the snake antenna array International Society for Magnetic Resonance in Medicine (Singapore pp 0395) Steensma B R, Voogt I J, Leiner T, Luijten P R, Habets J, KlompDWJ, van den BergCA T and Raaijmakers A J E 2018 An 8-Channel Tx/Rx dipole array combined with 16 Rx loops for high-resolution functional cardiac imaging at 7 T Magnetic Resonance Materials in Physics, Biology and Medicine 31 7–18 Sun H, Fessler J A, NollDCand Nielsen J-F 2016 Joint design of excitation k-space trajectory and RF pulse for small-tip 3D tailored excitation in MRI IEEE Transactions on Medical Imaging 35 468–79 Sutton B P, NollDCand Fessler J A 2003 Fast, iterative image reconstruction for MRI in the presence of field inhomogeneities IEEE Transactions on Medical Imaging 22 178–88 ThalhammerCet al 2012 Two-dimensional sixteen channel transmit/receive coil array for cardiac MRI at 7.0 T: design, evaluation, and application JMRI 36 847–57 Tian J, Lagore R L, Delabarre L and Vaughan J T 2016 Dipole array design considerations for head MRI at 10.5T International Society for Magnetic Resonance in Medicine (Singapore pp 3524) Tomi-Tricot R, Gras V, Thirion B, Mauconduit F, Boulant N, Cherkaoui H, Zerbib P, Vignaud A, Luciani Aand Amadon A 2019 SmartPulse, a machine learning approach for calibration-free dynamic RF shimming: preliminary study in a clinical environment Magnetic Resonance in Medicine 82 2016–31 Tomi-Tricot R, Sedlacik J, Endres J, Herrler J, Liebig P, Gumbrecht R, Ritter D, Wilkinson T, Brigden P, Giles S, Nagel AM, Hajnal JV, Neji R, Malik S J et al 2021 Fully integrated scanner implementation of direct signal control for 2D T2-weighted TSE at ultra-high field International Society for Magnetic Resonance in Medicine (Virtual pp 0621) Uğurbil K, Auerbach E, Moeller S, Grant A,WuX, Van de Moortele P-F, Olman C, DelaBarre L, Schillak S, Radder J, Lagore R, AdrianyG et al 2019 Brain imaging with improved acceleration and SNR at 7 Tesla obtained with 64-channel receive array Magnetic Resonance in Medicine 82 495–509 VaidyaMV, Collins CM, SodicksonDK, Brown R, WigginsGCand Lattanzi R 2016 Dependence of B1+and B1- field patterns of surface coils on the electrical properties of the sample and theMRoperating frequency Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 46 25–40 Vaughan J T, SnyderCJ, DelaBarre L J, Bolan P J, Tian J, Bolinger L, Adriany G, Andersen P, Strupp J, UgurbilKet al 2009 Whole-body imaging at 7T: preliminary resultsMagnetic Resonance in Medicine 61 244–8 Vaughan J T et al 2001 7T versus 4T: RF power, homogeneity, and signal-to-noise comparison in head images Magnetic Resonance in Medicine 46 24–30 Vaughan J T, HetheringtonHP, Otu JO, Pan JWand PohostGM1994 High frequency volume coils for clinicalNMRimaging and spectroscopy Magnetic Resonance in Medicine 32 206–18 Vaughan T, DelaBarre L, Snyder C, Tian J, Akgun C, Shrivastava D, Liu W, Olson C, Adriany G, Strupp J, Andersen P, Gopinath A, van de Moortele P-F, Garwood M, UgurbilKet al 2006 9.4T human MRI: preliminary results Magnetic Resonance in Medicine 56 1274–82 Van de Moortele P-F, Akgun C, Adriany G, Moeller S, Ritter J, CollinsCM, SmithMB, Vaughan J T andUğurbilK2005 B(1) destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil Magnetic Resonance in Medicine 54 1503–18 VanDamme L, Mauconduit F, Chambrion T, BoulantNand GrasV2020 Universal nonselective excitation and refocusing pulses with improved robustness to off-resonance for magnetic resonance imaging at 7 Tesla with parallel transmission Magnetic Resonance in Medicine 85 678–93 van den Bergen B, van den BergCA T, Bartels LWand Lagendijk J JW2007 7 T body MRI: B1 shimming with simultaneous SAR reduction Physics in Medicine&Biology 52 5429–41 VindingMS, AignerCS, Schmitter S and Lund T E 2020 DeepControl: 2D RF pulses facilitating B1+inhomogeneity and B0 off-resonance compensation in vivo at 7T Magnetic Resonance in Medicine 85 3308–17 Vossen M, Teeuwisse W, Reijnierse M, CollinsCM, SmithNB and Webb AG2011 A Radiofrequency coil configuration for imaging the human vertebral column at 7T Journal of Magnetic Resonance 208 291–7 Webb AGand Collins CM2010 Parallel transmit and receive technology in high-field magnetic resonance neuroimaging International Journal of Imaging Systems and Technology 20 2–13 Wiesinger F, Boesiger P and PruessmannKP 2004 Electrodynamics and ultimate SNR in parallelMRimaging Magnetic Resonance in Medicine 52 376–90 Wiesinger F, De ZancheNand PruessmannKP 2005 Approaching ultimate SNR with finite coil arrays International Society for Magnetic Resonance in Medicine (Miami Beach, FL, USA pp 672) 31 Phys. Med. Biol. 68 (2023) 02TR02 SNWilliams et al WigginsCJ, Hang M-F, Amadon A, Cloos M, Boulant N, Luong M, FerrandGand EdlerK2012 Combining cylindrically mounted dipoles with loops on a transverse plane for better head coverage in parallel transmission International Society for Magnetic Resonance in Medicine (Melbourne, Australia pp 2783) WigginsCJ, Zhang B, CloosMA, Lattanzi R, Chen G, Lakshmanan K, HaemerGGand SodicksonDK2013 Mixing loops and electric dipole antennas for increased sensitivity at 7 Tesla International Society for Magnetic Resonance in Medicine (Salt Lake City, UT, USA pp 2737) WigginsGC, LakshmananKand ChenG2015 The distributed inductance electric dipole antenna International Society for Magnetic Resonance in Medicine (Toronto, Canada pp 3100) Williams SN, Allwood-Spiers S, McElhinney P, Paterson G, Herrler J, Liebig P, Nagel AM, Foster J E, PorterDA and Gunamony S 2021a A nested eight-channel transmit array with open-face concept for human brain imaging at 7 Tesla Frontiers in Physics 9 1–16701330 Williams SN, Herrler J, Liebig P, McElhinney P, Shajan G, Nagel AMand PorterDA 2021b SAR management in pTx sequence design: the impact of electromagnetic-field-derived virtual observation points International Society for Magnetic Resonance in Medicine (Virtual pp 0412) p 0412 WillinekWA, Gieseke J, KukukGM, Nelles M, König R, Morakkabati-Spitz N, Träber F, Thomas D, Kuhl CKand SchildHH2010 Dualsource parallel radiofrequency excitation bodyMRimaging compared with standardMRimaging at 3.0 T: initial clinical experience Radiology 256 966–75 Wolf S, Diehl D, Gebhardt M, Mallow J and SpeckO2013 SAR simulations for high-field MRI: how much detail, effort, and accuracy is needed? Magnetic Resonance in Medicine 69 1157–68 WuB, Chunsheng W, KelleyDAC, Duan X, VigneronDB, Nelson S J and ZhangX 2010 Shielded microstrip array for 7T humanMR imaging IEEE Transactions on Medical Imaging 29 179–84 WuB, Wang C, Bammer R, KelleyDA, Xu Duan, Pang Yong, Banerjee S, VigneronDB, Nelson S J, Majumdar S and Zhang X2010 7T human spine imaging arrays with adjustable inductive decoupling IEEE Transactions on Biomedical Engineering 57 397-403 WuX, Schmitter S, Auerbach E J, UgurbilKand Van de Moortele PF 2014 Mitigating transmit B1 inhomogeneity in the liver at 7T using multi-spoke parallel transmit RF pulse design Quantitative Imaging in Medicine and Surgery 4 4–10 WuX, Tian J, Schmitter S, Vaughan J T,UğurbilKand Van de Moortele P-F 2016 Distributing coil elements in three dimensions enhances parallel transmission multiband RF performance: a simulation study in the human brain at 7 Tesla Magnetic Resonance in Medicine 75 2464–72 WuX, Vaughan J T,UğurbilKand Van de Moortele P-F 2010 Parallel excitation in the human brain at 9.4 T counteracting k -space errors with RF pulse design Magnetic Resonance in Medicine 63 524–9 Xu D, KingKF, Zhu Y, McKinnonGCand Liang Z-P 2008 Designing multichannel, multidimensional, arbitrary flip angle RF pulses using an optimal control approach Magnetic Resonance in Medicine 59 547–60 Yan X, Gore JCand GrissomWA 2018 Self-decoupled radiofrequency coils for magnetic resonance imaging Nature Communications 9 1–12 3481 Yan X, Wei L, Xue R and Zhang X2015 Hybrid monopole/loop coil array for human headMRimaging at 7 T Applied Magnetic Resonance 46 541–50 YangQX, Wang J, Zhang X, CollinsCM, SmithMB, Liu H, Zhu X-H, Vaughan J T,UğurbilKand ChenW2002 Analysis of wave behavior in lossy dielectric samples at high field Magnetic Resonance in Medicine 47 982–9 De ZancheNet al 2022 ISMRMbest practices for safety testing of experimental RF hardware International Society for Magnetic Resonance in Medicine 1–119 https://www.ismrm.org/safety/RF_Hardware_Safety_Testing_2022-03.pdf De Zanche N, Barmet C, Nordmeyer-Massner JA and PruessmannKP 2008NMRprobes for measuring magnetic fields and field dynamics inMRsystems Magnetic Resonance in Medicine 60 176–86 ZelinskiAC, Angelone LM, GoyalVK, Bonmassar G, Adalsteinsson E and Wald L L 2008 Specific absorption rate studies of the parallel transmission of inner-volume excitations at 7T Journal of Magnetic Resonance Imaging 28 1005–18 Zhang B, Adriany G, Delabarre L, Radder J, Lagore R, Rutt B, YangQX,UğurbilKand Lattanzi R 2021 Effect of radiofrequency shield diameter on signal-to-noise ratio at ultra-high field MRI Magnetic Resonance in Medicine 85 3522–30 Zhang B, Seifert AC, Kim J, Borrello J and Xu J 2017 7 Tesla 22-channel wrap-around coil array for cervical spinal cord and brainstem imaging Mag. Reson. Med. 78 1623–34 Zhang X,UğurbilKand ChenW2001 Microstrip RF surface coil design for extremely high-field MRI and spectroscopy Magnetic Resonance in Medicine 46 443–50 Zhao W, Cohen-Adad J, Polimeni J R, Keil B, Guerin B, Setsompop K, Serano P, Mareyam A, Hoecht P and Wald L L 2014 Nineteen-channel receive array and four-channel transmit array coil for cervical spinal cord imaging at 7T Magnetic Resonance in Medicine 72 291–300 Zhu Y 2004 Parallel excitation with an array of transmit coils Magnetic Resonance in Medicine 51 775–84

Deposit and Record Details

ID Code:	289776
Depositing User:	Dr Sydney Williams
Datestamp:	18 Jan 2023 10:01
Last Modified:	20 Jan 2023 15:00
Date of acceptance:	21 November 2022
Date of first online publication:	18 January 2023
Date Deposited:	17 January 2023
Data Availability Statement:	No