Improved RF performance of travelling wave MR with a high permittivity dielectric lining of the bore

A. Andreychenko*, J. J. Bluemink, A. J.E. Raaijmakers, J. J.W. Lagendijk, P. R. Luijten, C. A.T. Van Den Berg

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

Application of travelling wave MR to human body imaging is restricted by the limited peak power of the available RF amplifiers. Nevertheless, travelling wave MR advantages like a large field of view excitation and distant location of transmit elements would be desirable for whole body MRI. In this work, improvement of the B1+ efficiency of travelling wave MR is demonstrated. High permittivity dielectric lining placed next to the scanner bore wall effectively reduces attenuation of the travelling wave in the longitudinal direction and at the same time directs the radial power flow toward the load. First, this is shown with an analytical model of a metallic cylindrical waveguide with the dielectric lining next to the wall and loaded with a cylindrical phantom. Simulations and experiments also reveal an increase of B1+ efficiency in the center of the bore for travelling wave MR with a dielectric lining. Phantom experiments show up to a 2-fold gain in B1+ with the dielectric lining. This corresponds to a 4-fold increase in power efficiency of travelling wave MR. In vivo experiments demonstrate an 8-fold signal-to-noise ratio gain with the dielectric lining. Overall, it is shown that dielectric lining is a constructive method to improve efficacy of travelling wave MR.

Original languageEnglish
Pages (from-to)885-894
Number of pages10
JournalMagnetic Resonance in Medicine
Volume70
Issue number3
DOIs
Publication statusPublished - Sept 2013

Keywords

  • body MRI
  • dielectric lining
  • travelling wave
  • ultra high fields

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