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7T vs. 4T: RF power, homogeneity, and signal‐to‐noise comparison in head images
Author(s) -
Vaughan J.T.,
Garwood M.,
Collins C.M.,
Liu W.,
DelaBarre L.,
Adriany G.,
Andersen P.,
Merkle H.,
Goebel R.,
Smith M.B.,
Ugurbil K.
Publication year - 2001
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.1156
Subject(s) - head (geology) , nuclear magnetic resonance , human head , physics , homogeneity (statistics) , radio frequency , signal (programming language) , rf power amplifier , magnetic field , optics , telecommunications , mathematics , computer science , amplifier , optoelectronics , quantum mechanics , statistics , geomorphology , absorption (acoustics) , programming language , geology , cmos
Signal‐to‐noise ratio (SNR), RF field ( B 1 ), and RF power requirement for human head imaging were examined at 7T and 4T magnetic field strengths. The variation in B 1 magnitude was nearly twofold higher at 7T than at 4T (∼42% compared to ∼23%). The power required for a 90° pulse in the center of the head at 7T was approximately twice that at 4T. The SNR averaged over the brain was at least 1.6 times higher at 7T compared to 4T. These experimental results were consistent with calculations performed using a human head model and Maxwell's equations. Magn Reson Med 46:24–30, 2001. © 2001 Wiley‐Liss, Inc.