Monopole antenna array design for 3 T and 7 T magnetic resonance imaging

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radio Frequency (RF) Engineering
• Antenna Array Design

Background:

• Ultra-high field MRI presents significant challenges for conventional radio frequency (RF) coil designs.
• Birdcage coils, while common, have limitations in achieving optimal performance at higher field strengths.
• Novel RF coil designs are needed to overcome these limitations for advanced brain imaging applications.

Purpose of the Study:

• To evaluate the performance of monopole antenna arrays as an alternative RF coil for brain imaging.
• To compare the field properties and efficiency of monopole antenna arrays against birdcage coils at 3T and 7T MRI frequencies.
• To assess the scalability and practical performance of monopole antenna arrays.

Main Methods:

• Simulated four, eight, and twelve-element monopole antenna arrays and birdcage coils at 3T and 7T MRI frequencies.
• Evaluated and compared coil performance under unloaded, saline-loaded, and head phantom-loaded conditions.
• Fabricated and bench-tested a four-element monopole antenna array to assess matching and mutual coupling.

Main Results:

• Monopole antenna arrays demonstrated superior field properties and homogeneity compared to birdcage coils across all tested configurations and field strengths.
• The monopole antenna array exhibited higher efficiency and scalability through the addition of elements, unlike birdcage designs.
• Bench testing confirmed good impedance matching and low mutual coupling for the fabricated monopole antenna array.

Conclusions:

• Monopole antenna arrays generate greater field intensity and more homogeneous magnetic resonance imaging fields than birdcage coils.
• These findings suggest that RF monopole antenna arrays are a promising technology for advancing brain MRI.
• The improved performance indicates potential benefits for ultra-high field magnetic resonance imaging applications.