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Related Experiment Video

Updated: Feb 16, 2026

Optimization of Radiochemical Reactions using Droplet Arrays

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Published on: February 12, 2021

Optimal-permittivity Dielectric Liners for a 4.7T Transceiver Array.

Atefeh Kordzadeh¹, Nicola De Zanche²

¹Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada; Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada.

Magnetic Resonance Imaging

|December 27, 2017

Summary

High permittivity dielectric pads in magnetic resonance imaging (MRI) can degrade performance. An optimal, lower permittivity improves signal, reduces coupling, and enhances safety without air gaps.

Keywords:

Array coils Dielectric pads Dielectric resonance Matching layer Optimal permittivity RF safety SAR

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Published on: April 10, 2017

Area of Science:

Magnetic Resonance Imaging (MRI)
Electromagnetics
Biomedical Engineering

Background:

Dielectric pads enhance local signal and radio frequency (RF) magnetic field homogeneity in MRI.
High permittivity pads are increasingly used, necessitating investigation into their effects on RF coil arrays.

Purpose of the Study:

To evaluate the impact of larger dielectric liners on the transmit/receive performance of an 8-channel MRI array at 4.7T.
To determine the optimal dielectric permittivity for balancing homogeneity, efficiency, and safety.

Main Methods:

Electromagnetic simulations and experimental measurements were performed on an 8-channel array imaging a cylindrical phantom at 4.7T.
Investigated the effects of a dielectric liner with and without an air gap, analyzing coupling, efficiency, and specific absorption rate (SAR).

Main Results:

High permittivity liners degrade longitudinal homogeneity and increase SAR hot spots, causing dielectric resonances near the Larmor frequency.
An optimal, lower permittivity was identified that minimizes element coupling (<-23dB) and achieves performance equivalent to designs without an air gap.

Conclusions:

High permittivity dielectric pads are not recommended for MRI arrays due to performance degradation.
An optimal, lower permittivity offers improved transmit/receive performance, reduced coupling, and enhanced safety, achievable with cost-effective materials.