High permittivity ceramics improve the transmit field and receive efficiency of a commercial extremity coil at 1.5 Tesla

Irena Zivkovic, Wouter Teeuwisse, Alexey P. Slobozhanyuk, Elisaveta Nenasheva, Andrew Webb

Research output: Contribution to journalArticleAcademicpeer-review

33 Citations (Scopus)

Abstract

Objective
The purpose of this work is to investigate the use of ceramic materials (based on BaTiO3 with ZrO2 and CeO2-additives) with very high relative permittivity (εr ∼ 4500) to increase the local transmit field and signal-to-noise ratio (SNR) for commercial extremity coils on a clinical 1.5 T MRI system.

Methods
Electromagnetic simulations of transmit efficiency and specific absorption rate (SAR) were performed using four ferroelectric ceramic blocks placed around a cylindrical phantom, as well as placing these ceramics around the wrist of a human body model. Results were compared with experimental scans using the transmit body coil of the 1.5 T MRI system and an eight-element extremity receive array designed for the wrist. SNR measurements were also performed for both phantom and in vivo scans.

Results
Electromagnetic simulations and phantom/in vivo experiments showed an increased in the local transmit efficiency from the body coil of ∼20–30%, resulting in an ∼50% lower transmit power level and a significant reduction in local and global SAR throughout the body. For in vivo wrist experiments, the SNR of a commercial eight-channel receive array, integrated over the entire volume, was improved by ∼45% with the ceramic.

Conclusion
The local transmit efficiency as well as the SNR can be increased for 1.5 T extremity MRI with commercial array coils by using materials with very high permittivity.
Original languageEnglish
Pages (from-to)59-65
Number of pages7
JournalJournal of Magnetic Resonance
Volume299
DOIs
Publication statusPublished - Feb 2019
Externally publishedYes

Keywords

  • high permittivity dielectric
  • 1.5T MRI
  • Receive sensitivity
  • Reduced SAR
  • 1.5 T MRI
  • High permittivity materials
  • Transmit efficiency

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