A human cerebral and cerebellar 8-channel transceive RF dipole coil array at 7T.
AUTHORS: Clément J, Gruetter R, Ipek Ö
Magnetic Resonance in Medicine, 81: 1447-1458, February 2019
ABSTRACT
PURPOSE:
Dipole antennas that provide high transmit field penetration with large coverage, and their use in a parallel transmit setup, may be advantageous in minimizing B <mml:math xmlns:mml=”http://www.w3.org/1998/Math/MathML”><mml:msubsup><mml:mrow/> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:math> -field inhomogeneities at ultra-high field, i.e 7T. We have developed and evaluated an 8-channel RF dipole coil array for imaging the entire cerebral and cerebellar regions in man.
METHODS:
A coil array was modeled with seven dipoles: six placed covering the occipital and temporal lobes; one covering the parietal lobe; and two loops covering the frontal lobe. Center-shortened and fractionated dipoles were simulated for the array configuration and assessed with respect to B <mml:math xmlns:mml=”http://www.w3.org/1998/Math/MathML”><mml:msubsup><mml:mrow/> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:math> -field at maximum specific absorption rate averaged over 10 g tissue regions in human brain. The whole-brain center-shortened dipoles with frontal loops coil array was constructed and its transmit properties were assessed with respect to MR images, B <mml:math xmlns:mml=”http://www.w3.org/1998/Math/MathML”><mml:msubsup><mml:mrow/> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:math> -field, and homogeneity.
RESULTS:
In simulations, the dipole arrays showed comparable performances to cover the whole-brain. However, for ease of construction, the center-shortened dipole was favored. High spatial resolution anatomical images of the human brain with the coil array demonstrated a full coverage of the cerebral cortex and cerebellum.
CONCLUSIONS:
The 8-channel center-shortened dipoles and frontal loops coil array promises remarkable efficiency in highly challenging regions as the cerebellum, and phase-only RF shimming of whole-brain could greatly benefit ultra-high field magnetic resonance imaging of the human brain at 7T.
BibTex
Module: MRI