Resolution adapted finite element modeling of radio frequency interactions on conductive resonant structures in MRI.

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  • Author(s): Ruoff J;Ruoff J; Würslin C; Graf H; Schick F
  • Source:
    Magnetic resonance in medicine [Magn Reson Med] 2012 May; Vol. 67 (5), pp. 1444-52. Date of Electronic Publication: 2011 Nov 10.
  • Publication Type:
    Journal Article
  • Language:
    English
  • Additional Information
    • Source:
      Publisher: Wiley Country of Publication: United States NLM ID: 8505245 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1522-2594 (Electronic) Linking ISSN: 07403194 NLM ISO Abbreviation: Magn Reson Med Subsets: MEDLINE
    • Publication Information:
      Publication: 1999- : New York, NY : Wiley
      Original Publication: San Diego : Academic Press,
    • Subject Terms:
      Artifacts* ; Manufactured Materials* ; Metals* ; Prostheses and Implants*; Image Interpretation, Computer-Assisted/*methods ; Magnetic Resonance Imaging/*methods; Electric Conductivity ; Finite Element Analysis ; Radio Waves ; Reproducibility of Results ; Sensitivity and Specificity
    • Abstract:
      Prediction of interactions between the radiofrequency electromagnetic field in magnetic resonance scanners and electrically conductive material surrounded by tissue plays an increasing role for magnetic resonance safety. Testing of conductive implants or instruments is usually performed by standardized experimental setups and temperature measurements at distinct geometrical points, which cannot always reflect worst-case situations. A finite element method based on Matlab (The Mathworks, Natick, MA) and the finite element method program Comsol Multiphysics (Stockholm, Sweden) with a spatially highly variable mesh size solving Maxwell's full-wave equations was applied for a comprehensive simulation of the complete geometrical arrangement of typical birdcage radiofrequency coils loaded with small conductive structures in a homogenous medium. Conductive implants like rods of variable length and closed and open ring structures, partly exhibiting electromagnetic resonance behavior, were modeled and evaluated regarding the distribution of the B(1)- and E-field, induced currents and specific absorption rates. Numerical simulations corresponded well with experiments using a spin-echo sequence for visualization of marked B(1)-field inhomogeneities. Even resonance effects in conductive rods and open rings with suitable geometry were depicted accurately. The proposed method has high potential for complementation or even replacement of common experimental magnetic resonance compatibility measurements.
      (Copyright © 2011 Wiley Periodicals, Inc.)
    • Accession Number:
      0 (Metals)
    • Publication Date:
      Date Created: 20111115 Date Completed: 20120808 Latest Revision: 20150525
    • Publication Date:
      20221213
    • Accession Number:
      10.1002/mrm.23109
    • Accession Number:
      22076824