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

Objective: We present a 500 MHz inductive birdcage RF resonator for imaging the human brain in an 11.7 T MRI scanner. A homogenous circularly polarized transmit field (B1 +) was generated by transmitting power to the resonator through four couplers driven in differential mode and with an incremental 90-degree phase delay. A detailed mechanical and electrical model of the hardware, loaded with different phantoms, was generated and its performance simulated using a finite-difference timedomain method. The model was validated through bench and MRI measurements. This validation is important for future analysis of radiofrequency safety and performance through the prediction of SAR and B1 + profiles across different human brain models at various positions inside the coil.