Investigation of maximum local specific absorption rate in 7T magnetic resonance with respect to load size by use of electromagnetic simulations

Gianluigi Tiberi, Nunzia Fontana, Mauro Costagli, Riccardo Stara, Laura Biagi, Mark Roger Symms, Agostino Monorchio, Alessandra Retico, Mirco Cosottini, Michela Tosetti

Research output: Contribution to journalArticle

Abstract

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 7.0T 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.

Original languageEnglish
Pages (from-to)358-366
Number of pages9
JournalBioelectromagnetics
Volume36
Issue number5
DOIs
Publication statusPublished - Jul 1 2015

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Keywords

  • Anatomic human models
  • RF full-wave simulations
  • RF safety
  • SAR
  • Ultra high field Magnetic Resonance

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Physiology

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