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Parallel‐plate waveguide for volume radio frequency transmission in MRI
Author(s) -
Lu Hai,
Shang Shuo,
Wang Shumin
Publication year - 2015
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25517
Subject(s) - radiofrequency coil , electromagnetic coil , narrowband , broadband , radio frequency , bandwidth (computing) , acoustics , optics , transverse plane , materials science , transmitter , waveguide , nuclear magnetic resonance , physics , computer science , electrical engineering , telecommunications , engineering , channel (broadcasting) , structural engineering
Purpose Radiofrequency coils in MRI are narrowband resonant structures. The high‐quality factor makes their performance sensitive to loading and other operating conditions. We developed a new coil to provide volume transmit in a broad frequency band. Methods The proposed coil is a parallel‐plate waveguide. When operating in the transverse electromagnetic mode, a uniform magnetic field is generated between the plates for imaging. The impedance of the transverse electromagnetic mode is matched by a broadband matching circuit. The two plates are actively driven with broadband Wilkinson power dividers and combiners. Re‐entrant design is further applied to improve the overall efficiency. Results We developed a prototype of a coil to image the human forearm with a bandwidth of more than one octave. Its feasibility was demonstrated by proton imaging and phosphorous spectroscopy at 7T. Conclusions The proposed coil structure is compact and relatively easier to construct. It can be applied for volume radiofrequency transmit in MRI in a broad frequency band. Magn Reson Med 74:1482–1491, 2015. © 2014 Wiley Periodicals, Inc.