An 8-channel Tx/Rx dipole array combined with 16 Rx loops for high-resolution functional cardiac imaging at 7 T

B.R. Steensma, I.J. Voogt, T. Leiner, P.R. Luijten, J. Habets, D.W.J. Klomp, C.A.T. van den Berg, A.J.E. Raaijmakers

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Abstract

Objective: To demonstrate imaging performance for cardiac MR imaging at 7 T using a coil array of 8 transmit/receive dipole antennas and 16 receive loops. Materials and methods: An 8-channel dipole array was extended by adding 16 receive-only loops. Average power constraints were determined by electromagnetic simulations. Cine imaging was performed on eight healthy subjects. Geometrical factor (g-factor) maps were calculated to assess acceleration performance. Signal-to-noise ratio (SNR)-scaled images were reconstructed for different combinations of receive channels, to demonstrate the SNR benefits of combining loops and dipoles. Results: The overall image quality of the cardiac functional images was rated a 2.6 on a 4-point scale by two experienced radiologists. Imaging results at different acceleration factors demonstrate that acceleration factors up to 6 could be obtained while keeping the average g-factor below 1.27. SNR maps demonstrate that combining loops and dipoles provides a more than 50% enhancement of the SNR in the heart, compared to a situation where only loops or dipoles are used. Conclusion: This work demonstrates the performance of a combined loop/dipole array for cardiac imaging at 7 T. With this array, acceleration factors of 6 are possible without increasing the average g-factor in the heart beyond 1.27. Combining loops and dipoles in receive mode enhances the SNR compared to receiving with loops or dipoles only.

Original languageEnglish
Pages (from-to)7-18
Number of pages12
JournalMagnetic Resonance Materials in Physics, Biology and Medicine (MAGMA)
Volume31
Issue number1
DOIs
Publication statusPublished - 1 Feb 2018

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Keywords

  • Cardiac imaging
  • Dipole antennas
  • RF coil arrays
  • Ultrahigh field

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