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A numerical investigation on the effect of RF coil feed variability on global and local electromagnetic field exposure in human body models at 64 MH z
Author(s) -
Lucano Elena,
Liberti Micaela,
Lloyd Tom,
Apollonio Francesca,
Wedan Steve,
Kainz Wolfgang,
Angelone Leonardo M.
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26703
Subject(s) - specific absorption rate , electromagnetic coil , orientation (vector space) , position (finance) , bioelectromagnetics , radiofrequency coil , nuclear magnetic resonance , magnetic field , radio frequency , electromagnetic field , magnetic resonance imaging , absorption (acoustics) , physics , acoustics , field (mathematics) , computational physics , materials science , magnetostatics , biomedical engineering , computer science , mathematics , telecommunications , medicine , radiology , geometry , finance , quantum mechanics , pure mathematics , antenna (radio) , economics
Purpose This study aims to investigate how the positions of the feeding sources of the transmit radiofrequency (RF) coil, field orientation direction with respect to the patient, and patient dimensions affect the global and local electromagnetic exposure in human body models. Methods Three RF coil models were implemented, namely a specific two‐source (S2) feed and two multisource feed configurations: generic 32‐source (G32) and hybrid 16‐source (H16). Thirty‐two feeding conditions were studied for the S2, whereas two were studied for the G32 and H16. The study was performed using five human body models. Additionally, for two of the body models, the case of a partially implanted lead was evaluated. Results The results showed an overall variation due to coil feeding conditions of the whole‐body specific absorption rate (SAR) of less than 20%, but deviations up to 98% of the magnitude of the electric field tangential to a possible lead path. For the analysis with the partially implanted lead, a variation of local SAR at the tip of the lead of up to 60% was observed with respect to feed position and field orientation direction. Conclusion The results of this study suggest that specific information about feed position and field orientation direction must be considered for an accurate evaluation of patient exposure. Magn Reson Med 79:1135–1144, 2018. © 2017 International Society for Magnetic Resonance in Medicine.