Spatial and temporal variations of flip-angle distributions in the human brain using an eight-channel parallel transmission system at 7T: comparison of three radiofrequency excitation methods

We investigated the spatial and temporal variations of flip-angle (FA) distributions in the human brain from multiple scans, using an eight-channel parallel transmission (pTx) system at 7T. Nine healthy volunteers were scanned in five sessions using three radiofrequency excitation techniques each ti...

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Bibliographic Details
Published in:Radiological physics and technology 2021-06, Vol.14 (2), p.161-166
Main Authors: Matsuda, Tsuyoshi, Uwano, Ikuko, Iwadate, Yuji, Yoshioka, Kunihiro, Sasaki, Makoto
Format: Article
Language:English
Subjects:
Brain
Circular polarization
Coefficient of variation
Excitation
Imaging
Mathematical analysis
Medical and Radiation Physics
Medicine
Medicine & Public Health
Nuclear Medicine
Radio frequency
Radiology
Radiotherapy
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Summary:We investigated the spatial and temporal variations of flip-angle (FA) distributions in the human brain from multiple scans, using an eight-channel parallel transmission (pTx) system at 7T. Nine healthy volunteers were scanned in five sessions using three radiofrequency excitation techniques each time: circular polarization (CP), static pTx, and dynamic pTx. We calculated the coefficients of variation of the FA values within the brain area to evaluate the variations, and the maximum intersession differences in the FA values (D max ), comparing them between the three methods. The coefficients of variation decreased in the following order: CP, static pTx, and dynamic pTx (median: 20.1%, 13.6%, and 5.7%, respectively; p  
ISSN:1865-0333
1865-0341
DOI:10.1007/s12194-021-00612-8