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7T vs. 4T: RF power, homogeneity, and signal‐to‐noise comparison in head images

Magnetic Resonance in Medicine · 2001 · Vol. 46(1) · pp. 24–30

J. Thomas Vaughan✉(University of Minnesota)Michael Garwood(University of Minnesota)Christopher M. Collins(Pennsylvania State University)W. Liu(Pennsylvania State University)Lance DelaBarre(University of Minnesota)Gregor Adriany(University of Minnesota)Peter E. Andersen(University of Minnesota)Hellmut Merkle(University of Minnesota)Rainer Goebel(Brain Innovation (Netherlands))Michael B. Smith(Pennsylvania State University)Kâmil Uǧurbil(University of Minnesota)

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Abstract

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 ( approximately 42% compared to approximately 23%). The power required for a 90 degrees 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.

Advanced MRI Techniques and Applications Ultrasound Imaging and Elastography Atomic and Subatomic Physics ResearchHead (geology)Nuclear magnetic resonanceHuman headPhysicsHomogeneity (statistics)Radio frequencySIGNAL (programming language)RF power amplifierMagnetic fieldOptics