Numerical comparison of local transceiver arrays of fractionated dipoles and microstrip antennas for body imaging at 7 T.

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Abstrakt

Tytuł:: Numerical comparison of local transceiver arrays of fractionated dipoles and microstrip antennas for body imaging at 7 T.
Autorzy:: Stelter JK; Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Ladd ME; Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.; Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany.; Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, Germany.; Faculty of Medicine, Heidelberg University, Heidelberg, Germany.
Fiedler TM; Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Źródło:: NMR in biomedicine [NMR Biomed] 2022 Aug; Vol. 35 (8), pp. e4722. Date of Electronic Publication: 2022 Mar 17.
Typ publikacji:: Journal Article; Research Support, Non-U.S. Gov't
Język:: English
Imprint Name(s):: Publication: Chichester : Wiley
Original Publication: London : Heyden & Son, 1988-
MeSH Terms:: Magnetic Resonance Imaging*/instrumentation
Magnetic Resonance Imaging*/methods
Models, Anatomic*
Equipment Design ; Female ; Humans ; Male ; Phantoms, Imaging ; Signal-To-Noise Ratio
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Contributed Indexing:: Keywords: body imaging; dipole antennas; microstrip antennas; transmit arrays; ultra-high field
Entry Date(s):: Date Created: 20220228 Date Completed: 20220708 Latest Revision: 20220810
Update Code:: 20240104
DOI:: 10.1002/nbm.4722
PMID:: 35226966
: Czasopismo naukowe

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Longitudinally orientated dipoles and microstrip antennas have both demonstrated superior results as RF transmit elements for body imaging at 7 T MRI, and are as of today the most commonly used transmit elements. In this study, the performances of the two antenna concepts were compared for use in local RF antenna arrays by numerical simulations. Antenna elements investigated are the fractionated dipole and the microstrip line with meander structures. Phantom simulations with a single antenna element were performed and evaluated with regard to specific absorption rate (SAR) efficiency in the center of the subject. Simulations of array configurations with 8 and 16 elements were performed with anatomical body models. Both antenna elements were combined with a loop coil to compare hybrid configurations. Singular value decomposition of the B 1 + fields, RF shimming, and calculation of the voxel-wise power and SAR efficiencies were performed in regions of interest with varying sizes to evaluate the transmit performance. The signal-to-noise ratio (SNR) was evaluated to estimate the receive performance. Simulated data show similar transmit profiles for the two antenna types in the center of the phantom (penetration depth > 20 mm). For body imaging, no considerable differences were determined for the different antenna configurations with regard to the transmit performance. Results show the advantage of 16 transmit channels compared with today's commonly used 8-channel systems (minimum RF shimming excitation error of 4.7% (4.3%) versus 2.7% (2.8%) for the 8-channel and 16-channel configurations with the microstrip antennas in a (5 cm) 3 cube in the center of a male (female) body model). Highest SNR is achieved for the 16-channel configuration with fractionated dipoles. The combination of either fractionated dipoles or microstrip antennas with loop coils is more favorable with regard to the transmit performance compared with only increasing the number of elements.
(© 2022 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

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