Folded-end dipole transceiver array for human whole-brain imaging at 7 T

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Electrical Engineering

Background:

• Advancing clinical applications of ultrahigh field (UHF) MRI relies on technological progress, particularly in radiofrequency (RF) coil design.
• Limited availability of commercial 7 Tesla (7T) head RF coils necessitates the development of novel designs with enhanced performance.
• RF coil reliability is crucial for clinical use, as transmit channel failure can lead to increased local specific absorption rate and tissue heating.

Purpose of the Study:

• To develop, construct, and evaluate a novel eight-element transceiver bent folded-end dipole array for human head imaging at 7T.
• To assess the transmit efficiency, signal-to-noise ratio, and whole-brain coverage of the new dipole array compared to existing commercial designs.
• To investigate the effectiveness of passive dipole antennas for decoupling the proposed array and minimizing interference.

Main Methods:

• Development and construction of an eight-element transceiver bent folded-end dipole array.
• Evaluation of the array's performance in quadrature circularly polarized mode for 7T human head imaging.
• Assessment of passive dipole antennas for decoupling adjacent active dipoles and preserving the quadrature mode.

Main Results:

• The novel bent folded-end dipole array demonstrated over 20% higher transmit efficiency compared to a widely used commercial array.
• The developed array provided significantly better whole-brain coverage.
• Passive dipoles, positioned away from the sample, effectively minimized coupling between active dipoles without causing destructive interference with the quadrature mode.

Conclusions:

• The developed eight-element transceiver bent folded-end dipole array represents a significant advancement for 7T human head MRI.
• This novel RF coil design offers superior transmit efficiency and whole-brain coverage, addressing limitations of current commercial coils.
• The use of passive dipoles for decoupling provides a robust solution for maintaining array performance and safety in UHF MRI applications.