Unshielded bent folded-end dipole 9.4 T human head transceiver array decoupled using modified passive dipoles

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radio Frequency (RF) Engineering
• Biomedical Engineering

Background:

• High-field MRI (9.4T) offers enhanced signal-to-noise ratio for human head imaging.
• Decoupling adjacent elements in RF transceiver arrays is crucial for optimal performance.
• Traditional decoupling methods are challenging for dipole arrays due to element spacing.

Purpose of the Study:

• To develop an unshielded dipole transceiver array for 9.4T human head imaging.
• To enhance decoupling between adjacent dipole elements.
• To minimize radiofrequency interference in the array.

Main Methods:

• Designed a novel array with 8 bent folded-end dipole elements.
• Utilized passive dipoles for decoupling, placed perpendicularly to active dipoles and at array ends.
• Optimized transmit performance by adjusting the length of the dipole folded portion.

Main Results:

• Minimized destructive interference by rotating passive dipoles 90º and moving them to array ends.
• Achieved acceptable interference levels without compromising decoupling or transmit efficiency.
• Demonstrated good decoupling and whole-brain coverage with the constructed array.

Conclusions:

• Modified passive dipoles offer reduced destructive interference compared to common designs.
• The developed transceiver array maintains the benefits of passive dipole decoupling.
• The array is suitable for high-field human head MRI, providing good decoupling and coverage.