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Adjustable RF Transmitter Head Coil: Improving Transmit Efficiency With SAR Management for 7-T Magnetic Resonance Imaging
- Source :
- IEEE Transactions on Microwave Theory and Techniques. 69:2686-2696
- Publication Year :
- 2021
- Publisher :
- Institute of Electrical and Electronics Engineers (IEEE), 2021.
-
Abstract
- In ultrahigh field magnetic resonance imaging (MRI) using a static magnetic field over 7 T, the inhomogeneity in the time-varying magnetic field ( $B_{1}$ ), which is caused by its short wavelength, is mitigated by using a multichannel radio frequency (RF) coil as an antenna. However, the conventional multichannel RF coil has a fixed configuration; consequently, its transmit efficiency (TE) changes according to the head shape of the patient. In this study, a geometrically adjustable eight-channel RF transmitter head coil for 7-T MRI was proposed. All resonators and supporting structures (called bridges) in the coil have interlocking teeth at their sides, allowing each channel to adjust its geometric location according to the head shape of the patient. Scenarios for conventional and proposed coils in three different configurations were simulated and compared in terms of the transmitted component of the $B_{1}$ field ( $B_{1}^{+}$ field) and specific absorption rate (SAR) maps. The simulation results indicate that, for a given configuration and head shape, the TE of the proposed coil was higher than that of the conventional coil, while the SAR efficiency remained unchanged. Furthermore, the S-parameter matrix of the proposed coil and the measured $B_{1}$ field produced by the two channels facing each other show that the proposed coil resonates at 298 MHz with acceptable mutual coupling and effectively improves the $B_{1}$ field intensity. Moreover, the obtained signal-to-noise ratio (SNR) maps and magnetic resonance (MR) images prove that the proposed coil is an efficient candidate for an RF transmitter or transceiver head coil used in 7-T MRI.
- Subjects :
- Physics
Radiation
business.industry
Physics::Medical Physics
Specific absorption rate
020206 networking & telecommunications
02 engineering and technology
Condensed Matter Physics
Coupling (probability)
Magnetostatics
Resonator
Optics
Electromagnetic coil
0202 electrical engineering, electronic engineering, information engineering
Radio frequency
Electrical and Electronic Engineering
Antenna (radio)
business
Radiofrequency coil
Subjects
Details
- ISSN :
- 15579670 and 00189480
- Volume :
- 69
- Database :
- OpenAIRE
- Journal :
- IEEE Transactions on Microwave Theory and Techniques
- Accession number :
- edsair.doi...........df47a5b78f1331719ac10920b6324019