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

J. T Vaughan, Michael Garwood, C. M. Collins, W. Liu, Lance DelaBarre, Gregor Adriany, Peter M Andersen, H. Merkle, R. Goebel, M. B. Smith, Kamil Ugurbil

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Abstract

Signal-to-noise ratio (SNR), RF field (B1), and RF power requirement for human head imaging were examined at 7T and 4T magnetic field strengths. The variation in B1 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.

Original languageEnglish (US)
Pages (from-to)24-30
Number of pages7
JournalMagnetic resonance in medicine
Volume46
Issue number1
DOIs
StatePublished - Jul 10 2001

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Keywords

  • High-field MRI
  • RF homogeneity
  • RF power
  • Signal-to-noise

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