A Novel Mono-surface Antisymmetric 8Tx/16Rx Coil Array for Parallel Transmit Cardiac MRI in Pigs at 7T

Sci Rep. 2020 Feb 20;10(1):3117. doi: 10.1038/s41598-020-59949-6.

Abstract

A novel mono-surface antisymmetric 16-element transmit/receive (Tx/Rx) coil array was designed, simulated, constructed, and tested for cardiac magnetic resonance imaging (cMRI) in pigs at 7 T. The cardiac array comprised of a mono-surface 16-loops with two central elements arranged anti-symmetrically and flanked by seven elements on either side. The array was configured for parallel transmit (pTx) mode to have an eight channel transmit and 16-channel receive (8Tx/16Rx) coil array. Electromagnetic (EM) simulations, bench-top measurements, phantom, and MRI experiments with two pig cadavers (68 and 46 kg) were performed. Finally, the coil was used in pilot in-vivo measurements with a 60 kg pig. Flip angle (FA), geometry factor (g-factor), signal-to-noise ratio (SNR) maps, and high-resolution cardiac images were acquired with an in-plane resolution of 0.6 mm × 0.6 mm (in-vivo) and 0.3 mm × 0.3 mm (ex-vivo). The mean g-factor over the heart was 1.26 (R = 6). Static phase [Formula: see text] shimming in a pig body phantom with the optimal phase vectors makes possible to improve the [Formula: see text] homogeneity by factor > 2 and transmit efficiency by factor > 3 compared to zero phases (before RF shimming). Parallel imaging performed in the in-vivo measurements demonstrated well preserved diagnostic quality of the resulting images at acceleration factors up to R = 6. The described hardware design can be adapted for arrays optimized for animals and humans with a larger number of elements (32-64) while maintaining good decoupling for various MRI applications at UHF (e.g., cardiac, head, and spine).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomedical Engineering / instrumentation*
  • Cadaver
  • Electromagnetic Radiation
  • Equipment Design
  • Heart / diagnostic imaging*
  • Magnetic Resonance Imaging / instrumentation*
  • Magnetic Resonance Imaging / methods
  • Phantoms, Imaging
  • Signal-To-Noise Ratio
  • Swine