RF B1 field localization through convex optimization

Chris Olson, Hyoungsuk Yoo, Lance DelaBarre, J. Thomas Vaughan, Anand Gopinath

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

A 9-cm wavelength in the human brain at the 400-MHz Larmor frequency for 9.4-T leads to pronounced B1 field contours and consequential image inhomogeneity. The objective of this study was to develop a new technique to control this nonuniformity by designing the phase and magnitude of radiofrequency (RF) power emanating from RF coil antenna elements in a multichannel transceiver array. Nonuniformity was used to steer a constructively interfering B1 field node to spatially correlate with an anatomic region of interest. This work outlines a convex (quadratically constrained quadratic problem) formulation of the B1 localization problem and the benefits of such a formulation. This convex formulation was used to design antenna excitation magnitude and phase. Localization is demonstrated in simulated finite difference time domain (FDTD) B1 field human head distributions and human head phantom measurement.

Original languageEnglish (US)
Pages (from-to)31-37
Number of pages7
JournalMicrowave and Optical Technology Letters
Volume54
Issue number1
DOIs
StatePublished - Jan 1 2012

Keywords

  • RF B field
  • convex optimization
  • magnetic resonance imaging
  • radiofrequency coil
  • transmission line element

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