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Investigation of maximum local specific absorption rate in 7 T magnetic resonance with respect to load size by use of electromagnetic simulations
Author(s) -
Tiberi Gianluigi,
Fontaunzia,
Costagli Mauro,
Stara Riccardo,
Biagi Laura,
Symms Mark Roger,
Monorchio Agostino,
Retico Alessandra,
Cosottini Mirco,
Tosetti Michela
Publication year - 2015
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.21907
Subject(s) - specific absorption rate , electromagnetic coil , radiofrequency coil , ultra high frequency , magnetic field , electromagnetic simulation , electromagnetic field , absorption (acoustics) , acoustics , nuclear magnetic resonance , materials science , radio frequency , computational physics , volume (thermodynamics) , magnetic resonance imaging , physics , mechanics , computer science , telecommunications , electronic engineering , engineering , radiology , quantum mechanics , antenna (radio) , medicine
Local specific absorption rate (SAR) evaluation in ultra high field (UHF) magnetic resonance (MR) systems is a major concern. In fact, at UHF, radiofrequency (RF) field inhomogeneity generates hot‐spots that could cause localized tissue heating. Unfortunately, local SAR measurements are not available in present MR systems; thus, electromagnetic simulations must be performed for RF fields and SAR analysis. In this study, we used three‐dimensional full‐wave numerical electromagnetic simulations to investigate the dependence of local SAR at 7.0 T with respect to subject size in two different scenarios: surface coil loaded by adult and child calves and quadrature volume coil loaded by adult and child heads. In the surface coil scenario, maximum local SAR decreased with decreasing load size, provided that the RF magnetic fields for the different load sizes were scaled to achieve the same slice average value. On the contrary, in the volume coil scenario, maximum local SAR was up to 15% higher in children than in adults. Bioelectromagnetics. 36:358–366, 2015. © 2015 Wiley Periodicals, Inc.