500 MHz Inductive Birdcage RF Coil for Brain MRI: Design, Implementation and Validation.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Engineering
• Biomedical Engineering

Background:

• Ultra-high field (UHF) MRI scanners, such as 11.7 T, offer enhanced signal-to-noise ratio for improved human brain imaging.
• Designing efficient and safe RF resonators is critical for optimal performance and minimizing radiofrequency-induced heating at UHF.

Purpose of the Study:

• To present a novel 500 MHz inductive birdcage radiofrequency (RF) resonator specifically designed for human brain imaging at 11.7 T.
• To validate the performance and safety of the developed RF resonator through simulation and experimental measurements.

Main Methods:

• Developed a 500 MHz inductive birdcage RF resonator for head imaging.
• Generated a detailed mechanical and electrical model of the resonator with phantoms.
• Simulated resonator performance using the finite-difference time-domain (FDTD) method.
• Validated the model through bench measurements and MRI experiments, including MR thermometry.

Main Results:

• The head-sized birdcage resonator operated at its fundamental mode of 500 MHz.
• Simulated Specific Absorption Rate (SAR) maps showed good agreement with MR thermometry heating profiles.
• The computational model was successfully validated by both bench and MRI measurements.

Conclusions:

• The developed 500 MHz birdcage resonator is suitable for human brain imaging at 11.7 T.
• The validated model is crucial for predicting radiofrequency safety and B1+ profiles in various human brain models at UHF MRI.
• This work facilitates future analysis of RF safety and performance in ultra-high field MRI.