Comparison of B1 Field Homogeneity for Shielded Birdcage, TEM and Microstrip Volume Coils at 300MHz

Introduction: Because of the inherent advantage of improved SNR, ultra-high field (3T~9.4T) MRI technology and applications have been accelerated these years. However many engineering challenges have arisen from high-operation frequencies. One major challenge is the difficulty of designing large-size RF coils with high-resonance frequencies. In addition, it has been shown that the homogeneity of the radio frequency (RF) magnetic field, B1, will progressively decrease in large samples with increasing B1 frequency. This is mainly caused by the dielectric resonance phenomenon [1]. Due to distributed element and intrinsic shield, TEM [2] and microstrip [3] volume coils can be used for very high field. Improved birdcage coil with tight RF shield, widening rung, etc. also can be used and reported at 7T [4]. In order to reveal which one has better B1 homogeneity these three kinds of volume coils were simulated and compared by FDTD method in this work.