Maunder, A., Rao, M., Robb, F. et al. (1 more author) (2018) Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils. Magnetic Resonance in Medicine, 80 (4). pp. 1746-1753. ISSN 0740-3194
Abstract
PURPOSE: To evaluate the performance of micro-electromechanical systems (MEMS) switches against PIN diodes for switching a dual-tuned RF coil between19F and1H resonant frequencies for multi-nuclear lung imaging. METHODS: A four-element fixed-phase and amplitude transmit-receive RF coil was constructed to provide homogeneous excitation across the lungs, and to serve as a test system for various switching methods. The MR imaging and RF performance of the coil when switched between the19F and1H frequencies using MEMS switches, PIN diodes and hardwired configurations were compared. RESULTS: The performance of the coil with MEMS or PIN diode switching was comparable in terms of RF measurements, transmit efficiency and image SNR on both19F and1H nuclei. When the coil was not switched to the resonance frequency of the respective nucleus being imaged, reductions in the transmit efficiency were observed of 32% at the19F frequency and 12% at the1H frequency. The coil provides transmit field homogeneity of ±12.9% at the1H frequency and ±14.4% at the19F frequency in phantoms representing the thorax with the air space of the lungs filled with perfluoropropane gas. CONCLUSION: MEMS and PIN diodes were found to provide comparable performance in on-state configuration, while MEMS were more robust in off-state high-powered operation (>1 kW), providing higher isolation and requiring a lower DC switching voltage than is needed for reverse biasing of PIN diodes. In addition, clear benefits of switching between the19F and1H resonances were demonstrated, despite the proximity of their Larmor frequencies.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Dual Tuned RF coils; Micro-electromechanical systems (MEMS); PIN diode; Switchable RF coils; fluorine-19 MRI; lung MRI |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > Department of Infection, Immunity and Cardiovascular Disease The University of Sheffield > Sheffield Teaching Hospitals |
Funding Information: | Funder Grant number MEDICAL RESEARCH COUNCIL MR/M008894/1 MEDICAL RESEARCH COUNCIL MR/M008894/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Mar 2018 11:14 |
Last Modified: | 11 Nov 2020 12:19 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1002/mrm.27156 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:128821 |
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