The fractionated dipole antenna: a new antenna for body imaging at 7 Tesla

A,J.E. Raaijmakers, M.G.M. Italiaander, I.J. Voogt, P.R. Luijten, J.M. Hoogduin, D.W.J. Klomp, C.A.T. van den Berg

Research output: Contribution to journalArticleAcademicpeer-review

101 Citations (Scopus)

Abstract

PURPOSE: Dipole antennas in ultrahigh field MRI have demonstrated advantages over more conventional designs. In this study, the fractionated dipole antenna is presented: a dipole where the legs are split into segments that are interconnected by capacitors or inductors.

METHODS: A parameter study has been performed on dipole antenna length using numerical simulations. A subsequent simulation study investigates the optimal intersegment capacitor/inductor value. The resulting optimal design has been constructed and compared to a previous design, the single-side adapted dipole (SSAD) by simulations and measurements. An array of eight elements has been constructed for prostate imaging on four subjects (body mass index 20-27.5) using 8 × 2 kW amplifiers.

RESULTS: For prostate imaging at 7T, lowest peak local specific-absorption rate (SAR) levels are achieved if the antenna is 30 cm or longer. A fractionated dipole antenna design with inductors between segments has been chosen to achieve even lower SAR levels and more homogeneous receive sensitivities.

CONCLUSION: With the new design, good quality prostate images are acquired. SAR levels are reduced by 41% to 63% in comparison to the SSAD. Coupling levels are moderate (average nearest neighbor: -14.6 dB) for each subject and prostate B1+ levels range from 12 to 18 μT.

Original languageEnglish
Pages (from-to)1366-1374
Number of pages9
JournalMagnetic Resonance in Medicine
Volume75
Issue number3
DOIs
Publication statusPublished - Mar 2016
Externally publishedYes

Keywords

  • Adult
  • Computer Simulation
  • Equipment Design
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Phantoms, Imaging
  • Prostate
  • Signal-To-Noise Ratio
  • Young Adult
  • Journal Article

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