Journal Article

DKFZ-2022-00385

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Numerical Comparison of Local Transceiver Arrays of Fractionated Dipoles and Microstrip Antennas for Body Imaging at 7 T.

Stelter, J. (First author)DKFZ* ; Ladd, M. E.DKFZ* ; Fiedler, T. (Last author)DKFZ*

2022
Wiley New York, NY

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Please use a persistent id in citations: doi:10.1002/nbm.4722

Abstract: 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 performance of both antenna concepts was compared for use in local RF antenna arrays by numerical simulations. Investigated antenna elements 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 B1 + fields, RF shimming, and calculation of the voxel-wise power and SAR efficiencies were performed in regions of interest (ROIs) 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 both 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 to today's commonly used 8-channel systems (minimum RF shimming excitation error of 4.7% (4.3%) vs. 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 to only increasing the number of elements.

Keyword(s): body imaging ; dipole antennas ; microstrip antennas ; transmit arrays ; ultrahigh field

Note: #EA:E020#LA:E020# /2022 Aug;35(8):e4722

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Contributing Institute(s):

1. E020 Med. Physik in der Radiologie (E020)

Research Program(s):

1. 315 - Bildgebung und Radioonkologie (POF4-315) (POF4-315)

Appears in the scientific report 2022

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Life Sciences ; DEAL Wiley ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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