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Human brain imaging at 9.4 T using a tunable patch antenna for transmission

Authors

  • Jens Hoffmann,

    1. Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Tübingen 72076, Germany
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  • G. Shajan,

    1. Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Tübingen 72076, Germany
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  • Juliane Budde,

    1. Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Tübingen 72076, Germany
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  • Klaus Scheffler,

    1. Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Tübingen 72076, Germany
    2. Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen 72076, Germany
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  • Rolf Pohmann

    Corresponding author
    1. Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Tübingen 72076, Germany
    • Max Planck Institute for Biological Cybernetics, High-Field Magnetic Resonance Center, Spemannstr. 41, 72076 Tübingen, Germany
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Abstract

For human brain imaging at ultrahigh fields, the traveling wave concept can provide a more uniform B1+ field over a larger field of view with improved patient comfort compared to conventional volume coils. It suffers, however, from limited transmit efficiency and receive sensitivity and is not readily applicable in systems where the radiofrequency shield is too narrow to allow for unattenuated wave propagation. Here, the near field of a capacitively adjustable patch antenna for excitation is combined with a receive-only array at 9.4 T. The antenna is designed in compact size and placed in close proximity to the subject to improve the transmit efficiency in narrow bores. Experimental and numerical comparisons to conventional microstrip arrays reveal improved B1+ homogeneity and longitudinal coverage, but at the cost of elevated local specific absorption rate. High-resolution functional and anatomical images demonstrate the use of this setup for in vivo human brain imaging at 9.4 T. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.

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