Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils.
Magn Reson Med
; 80(4): 1746-1753, 2018 10.
Article
en En
| MEDLINE
| ID: mdl-29524235
ABSTRACT
PURPOSE:
To evaluate the performance of micro-electromechanical systems (MEMS) switches against PIN diodes for switching a dual-tuned RF coil between 19 F and 1 H 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 the 19 F and 1 H 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 both 19 F and 1 H 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 the 19 F frequency and 12% at the 1 H frequency. The coil provides transmit field homogeneity of ±12.9% at the 1 H frequency and ±14.4% at the 19 F 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 the 19 F and 1 H resonances were demonstrated, despite the proximity of their Larmor frequencies.Palabras clave
Texto completo:
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Banco de datos:
MEDLINE
Asunto principal:
Sistemas Microelectromecánicos
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Imagen por Resonancia Magnética con Fluor-19
Límite:
Adult
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Humans
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Male
Idioma:
En
Año:
2018
Tipo del documento:
Article