Design of an Intraoral Dipole Antenna for Dental Applications

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: In dental MRI intraoral coils provide higher signal-to-noise ratio (SNR) than coils placed outside the mouth. This study aims to design an intraoral dipole antenna and demonstrates the feasibility of combining it with an extraoral coil.

METHODS: Dipole antenna design was chosen over loop design, as it is open toward the distal; therefore, it does not restrain tongue movement. The dipole design offers also an increased depth-of-sensitivity that allows for MRI of dental roots. Different dipole antenna designs were simulated using a finite-difference-time-domain approach. Ribbon, wire, and multi-wire arms were compared. The best design was improved further by covering the ends of the dipole arms with a high-permittivity material. Phantom and in vivo measurements were conducted on a 3T clinical MRI system.

RESULTS: The best transmit efficiency and homogeneity was achieved with a multi-wire curved dipole antenna with 7 wires for each arm. With an additional high-permittivity cap the transmit field inhomogeneity was further reduced from 20% to 5% along the dipole arm. When combined with extraoral flexible surface-coil, the coupling between the coils was less than -32dB and SNR was increased.

CONCLUSION: Using intraoral dipole design instead of loop improves patient comfort. We demonstrated feasibility of the intraoral dipole combined with an extraoral flexible coil-array for dental MRI. Dipole antenna enabled decreasing imaging field-of-view, and reduced the prevalent signal from tongue.

SIGNIFICANCE: This study highlights the advantages and the main challenges of the intraoral RF coils and describes a novel RF coil that addresses those challenges.

Original languageEnglish (US)
Article number9340554
Pages (from-to)2563-2573
Number of pages11
JournalIEEE Transactions on Biomedical Engineering
Volume68
Issue number8
Early online dateJan 29 2021
DOIs
StatePublished - Aug 2021

Bibliographical note

Funding Information:
Manuscript received July 28, 2020; revised October 22, 2020 and December 21, 2020; accepted January 26, 2021. Date of publication January 29, 2021; date of current version July 19, 2021. The work of Ali Caglar Özen was supported by the School of Dentistry of UMN’s Lasby Fellowship and in part by the Biomedical Technology Resource Center (BTRC) grant NIH (P41 EB025144). (Corresponding author: Ali Caglar Özen.) Ali Caglar Özen is with the Department of Radiology, Medical Physics, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, 79085 Freiburg, Germany, with the German Consortium for Translational Cancer Research Partner Site Freiburg, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany, and he was with the Division of TMD & Orofacial Pain, School of Dentistry, University of Minnesota, Minneapolis, MN 55402 USA (e-mail: a.oezen@uniklinik-freiburg.de).

Publisher Copyright:
© 1964-2012 IEEE.

Keywords

  • Dental MRI
  • Dipole Antenna
  • Intraoral Coil
  • Magnetic Resonance Imaging
  • Radiofrequency Coil

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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