Active decoupling of RF coils using a transmit array system

Ali C aglar Özen, Michael Bock, Ergin Atalar

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)565-576
Number of pages12
JournalMagma (New York, N.Y.)
Volume28
Issue number6
DOIs
StatePublished - Dec 1 2015
Externally publishedYes

Keywords

  • Concurrent excitation and acquisition
  • Continuous-wave NMR
  • Geometrical decoupling
  • Phase amplitude decoupling
  • Transmit array

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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