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Active decoupling of RF coils using a transmit array system

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Magnetic Resonance Materials in Physics, Biology and Medicine Aims and scope Submit manuscript

Abstract

Objective

Implementation of a decoupling method for isolation of transmit and receive radio frequency (RF) coils for concurrent excitation and acquisition (CEA) MRI in samples with ultra-short T2*.

Materials and methods

The new phase and amplitude (PA) decoupling method is implemented in a clinical 3T-MRI system equipped with a parallel transmit array system. For RF excitation, two transmit coils are used in combination with a single receive coil. The transmit coil is geometrically decoupled from the receive coil, and the remaining B 1-induced voltages in the receive coil during CEA are minimized by the second transmit coil using a careful adjustment of the phase and amplitude settings in this coil. Isolation of the decoupling scheme and transmit noise behavior are analyzed for different loading conditions, and a CEA MRI experiment is performed in a rubber phantom with sub-millisecond T2* and in an ex vivo animal.

Results

Geometrical (20 dB) and PA decoupling (50 dB) provided a total isolation of 70 dB between the transmit and receive coils. Integration of a low-noise RF amplifier was necessary to minimize RF transmit noise. CEA MR images could be reconstructed from a rubber phantom and an ex vivo animal.

Conclusion

CEA MRI can be implemented in clinical MRI systems using active decoupling with parallel transmit array capabilities with minor hardware modifications.

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Authors and Affiliations

  1. Department of Radiology, Medical Physics, University Medical Center Freiburg, 79106, Freiburg, Germany

    Ali Caglar Özen & Michael Bock

  2. Department of Electrical and Electronics Engineering, Bilkent University, 06800, Ankara, Turkey

    Ali Caglar Özen & Ergin Atalar

Authors
  1. Ali Caglar Özen
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  2. Michael Bock
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  3. Ergin Atalar
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Correspondence to Ali Caglar Özen.

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Özen, A.C., Bock, M. & Atalar, E. Active decoupling of RF coils using a transmit array system. Magn Reson Mater Phy 28, 565–576 (2015). https://doi.org/10.1007/s10334-015-0497-0

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  • DOI: https://doi.org/10.1007/s10334-015-0497-0

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