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Parallel transmit capability of various RF transmit elements and arrays at 7T MRI
Stefan H G Rietsch1,2, Stephan Orzada1, Andreas K Bitz3,4
1Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany.
Magnetic Resonance in Medicine
|April 11, 2017
Summary
Eight-element dipole arrays show the best performance for 7 Tesla (T) ultrahigh-field MRI. These configurations offer optimal power and specific absorption rate efficiency for body imaging applications.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Radiofrequency (RF) Engineering
- Biomedical Engineering
Background:
- Ultrahigh-field MRI at 7 Tesla (T) offers enhanced signal-to-noise ratio but presents challenges in RF coil design.
- Optimizing RF coil arrays is crucial for efficient and safe operation in 7T MRI.
Purpose of the Study:
- To compare 22 configurations of remote radiofrequency (RF) coil arrays for 7T MRI.
- To evaluate different transmit element designs and array configurations.
Main Methods:
- Numerical simulations were used to assess various RF coil elements including loops, micro striplines, and dipoles.
- Four circumferential RF body array configurations with four or eight elements were analyzed.
- Key metrics such as coupling, degrees of freedom, power efficiency, and specific absorption rate (SAR) efficiency were evaluated.
Main Results:
- Eight-element arrays exhibited higher coupling (-7 dB) compared to four-element arrays (<-25 dB).
- Dipole arrays demonstrated superior power and SAR efficiency.
- Highest degrees of freedom were observed in the transversal slice, with reduced values in coronal and sagittal slices.
Conclusions:
- A configuration of eight dipoles is most favorable for 7T body MRI.
- This configuration provides a good balance of performance metrics for advanced MRI applications.