High-Permittivity Pad Design for Dielectric Shimming in Magnetic Resonance Imaging Using Projection-Based Model Reduction and a Nonlinear Optimization Scheme

J.H.F. van Gemert, W.M. Brink, A.G. Webb, R.F. Remis

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)
15 Downloads (Pure)

Abstract

Inhomogeneities in the transmit radio frequency magnetic field ( {\text{B}}-{1}^{+} ) reduce the quality of magnetic resonance (MR) images. This quality can be improved by using high-permittivity pads that tailor the {\text{B}}-{1}^{+} fields. The design of an optimal pad is application-specific and not straightforward and would therefore benefit from a systematic optimization approach. In this paper, we propose such a method to efficiently design dielectric pads. To this end, a projection-based model order reduction technique is used that significantly decreases the dimension of the design problem. Subsequently, the resulting reduced-order model is incorporated in an optimization method in which a desired field in a region of interest can be set. The method is validated by designing a pad for imaging the cerebellum at 7 T. The optimal pad that is found is used in an MR measurement to demonstrate its effectiveness in improving the image quality.

Original languageEnglish
Pages (from-to)1035-1044
Number of pages10
JournalIEEE Transactions on Medical Imaging
Volume37
Issue number4
DOIs
Publication statusPublished - 2018

Keywords

  • dielectric shimming
  • fields
  • high-permittivity pads
  • Magnetic resonance imaging
  • optimization
  • reduced order modeling

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