A comparative numerical study of rotating and stationary RF coils in terms of flip angle and specific absorption rate for 7 T MRI

Trakic, A., Jin, J., Li, M., McClymont, D., Weber, E., Liu, F. and Crozier, S. (2013) A comparative numerical study of rotating and stationary RF coils in terms of flip angle and specific absorption rate for 7 T MRI. Journal of Magnetic Resonance, 236 70-82. doi:10.1016/j.jmr.2013.08.016


Author Trakic, A.
Jin, J.
Li, M.
McClymont, D.
Weber, E.
Liu, F.
Crozier, S.
Title A comparative numerical study of rotating and stationary RF coils in terms of flip angle and specific absorption rate for 7 T MRI
Journal name Journal of Magnetic Resonance   Check publisher's open access policy
ISSN 1090-7807
1096-0856
Publication date 2013-11
Sub-type Article (original research)
DOI 10.1016/j.jmr.2013.08.016
Open Access Status
Volume 236
Start page 70
End page 82
Total pages 13
Place of publication Maryland Heights, MO, United States
Publisher Academic Press
Collection year 2014
Language eng
Formatted abstract
Highlights
• RRFC produced a more uniform FA and SAR distribution than parallel and volume coils.
• The RRFC shimming performance is due to the very large number of sensitivity profiles.
• With RRFC there is no constructive interference of electric fields.

While high-field magnetic resonance imaging promises improved image quality and faster scan time, it is affected by non-uniform flip angle distributions and unsafe specific absorption rate levels within the patient, as a result of the complicated radiofrequency (RF) field – tissue interactions. This numerical study explored the possibility of using a single mechanically rotating RF coil for RF shimming and specific absorption rate management applications at 7 T. In particular, this new approach (with three different RF coil element arrangements) was compared against both an 8-channel parallel coil array and a birdcage volume coil, with and without RF current optimisation. The evaluation was conducted using an in-house developed and validated finite-difference time-domain method in conjunction with a tissue-equivalent human head model. It was found that, without current optimisation, the rotating RF coil method produced a more uniform flip angle distribution and a lower maximum global and local specific absorption rate compared to the 8-channel parallel coil array and birdcage resonator. In addition, due to the large number of degrees of freedom in the form of rotated sensitivity profiles, the rotating RF coil approach exhibited good RF shimming and specific absorption rate management performance. This suggests that the proposed method can be useful in the development of techniques that address contemporary RF issues associated with high-field magnetic resonance imaging.
Keyword High-field MRI
RF shimming
SAR
Rotating RF coil
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Information Technology and Electrical Engineering Publications
 
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Created: Tue, 22 Oct 2013, 17:23:19 EST by Mr Jin Jin on behalf of School of Information Technol and Elec Engineering