Abstract
We investigated global specific absorption rate (SAR) and radiofrequency (RF) power requirements in parallel transmission as the distance between the transmit coils and the sample was increased. We calculated ultimate intrinsic SAR (UISAR), which depends on object geometry and electrical properties but not on coil design, and we used it as the reference to compare the performance of various transmit arrays. We investigated the case of fixing coil size and increasing the number of coils while moving the array away from the sample, as well as the case of fixing coil number and scaling coil dimensions. We also investigated RF power requirements as a function of lift-off, and tracked local SAR distributions associated with global SAR optima. In all cases, the target excitation profile was achieved and global SAR (as well as associated maximum local SAR) decreased with lift-off, approaching UISAR, which was constant for all lift-offs. We observed a lift-off value that optimizes the balance between global SAR and power losses in coil conductors. We showed that, using parallel transmission, global SAR can decrease at ultra high fields for finite arrays with a sufficient number of transmit elements. For parallel transmission, the dista...Continue Reading
References
Jun 1, 1994·Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics·W S Weiglhofer, A Lakhtakia
Apr 3, 2001·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·C M Collins, M B Smith
Jan 2, 2003·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Ulrich KatscherJohan S van den Brink
Apr 6, 2004·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Yudong Zhu
Jul 30, 2004·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Florian WiesingerKlaas P Pruessmann
Aug 31, 2004·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Michael A OhligerDaniel K Sodickson
Feb 16, 2005·Magma·U KatscherP Börnert
Nov 2, 2005·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Peter Kellman, Elliot R McVeigh
Feb 28, 2007·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Cornelis A T Van den BergJan J W Lagendijk
May 24, 2007·Journal of Magnetic Resonance Imaging : JMRI·Tamer S Ibrahim, Lin Tang
Oct 31, 2007·Journal of Magnetic Resonance Imaging : JMRI·Frank SeifertHerbert Rinneberg
Sep 16, 2008·Irish Journal of Medical Science
Jan 24, 2009·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Riccardo LattanziYudong Zhu
Mar 4, 2009·Biochimica Et Biophysica Acta·Tomas Björklund, Deniz Kirik
Nov 12, 2009·NMR in Biomedicine·Riccardo LattanziDaniel K Sodickson
Sep 30, 2010·Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases·S M KotilaO Lyytikäinen
Jan 26, 2011·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Hanno HomannPeter Börnert
Dec 1, 2011·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Riccardo Lattanzi, Daniel K Sodickson
Dec 3, 2011·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Cem Murat DenizYudong Zhu
Mar 13, 2014·Journal of Molecular Neuroscience : MN
Nov 27, 2014·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Leeor AlonCem M Deniz
Citations
Apr 4, 2016·Magma·Gerd WeidemannBernd Ittermann
Sep 7, 2016·PloS One·Oliver WeinbergerThoralf Niendorf
Jun 13, 2019·Topics in Magnetic Resonance Imaging : TMRI·Oliver Kraff, Harald H Quick
Jun 13, 2019·Topics in Magnetic Resonance Imaging : TMRI·Cem M Deniz
Apr 18, 2020·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Emre KopanogluRichard G Wise
Sep 24, 2020·Magma·Stephan OrzadaHarald H Quick
May 5, 2021·NMR in Biomedicine·Thomas M FiedlerAndreas K Bitz
Dec 28, 2021·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Alix PlumleyEmre Kopanoglu