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High permittivity pads reduce specific absorption rate, improve B 1 homogeneity, and increase contrast‐to‐noise ratio for functional cardiac MRI at 3 T
Author(s) -
Brink Wyger M.,
Webb Andrew G.
Publication year - 2014
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.24778
Subject(s) - specific absorption rate , homogeneity (statistics) , contrast to noise ratio , materials science , permittivity , nuclear magnetic resonance , electromagnetic coil , magnetic resonance imaging , biomedical engineering , image quality , dielectric , physics , computer science , telecommunications , medicine , radiology , optoelectronics , quantum mechanics , machine learning , artificial intelligence , antenna (radio) , image (mathematics)
Purpose To improve image quality and reduce specific absorption rate in functional cardiac imaging at 3 T. Methods Two high permittivity dielectric pads on the anterior and posterior sides of the thorax were numerically designed and implemented using an aqueous suspension of barium titanate. The effects on the average transmit efficiency, B 1 homogeneity, reception sensitivity, and contrast‐to‐noise ratio were verified in vivo on a dual‐transmit system with the body coil driven in conventional quadrature and radiofrequency‐shimmed mode. Results Statistically significant improvements in average transmit efficiency, B 1 homogeneity, and contrast‐to‐noise ratio were measured in healthy volunteers ( n = 11) with body mass indices between 20.3 and 34.9. Simulations show that no radiofrequency hot spots are introduced by the dielectric material. Conclusion High permittivity pads are shown to reduce specific absorption rate, improve B 1 homogeneity, and increase contrast‐to‐noise ratio in functional cardiac magnetic resonance at 3 T. The results presented in this work show that the current approach is more effective than dual‐channel radiofrequency shimming. Magn Reson Med 71:1632–1640, 2014. © 2013 Wiley Periodicals, Inc .