Simulation Design of Incremental Leg Tapered Birdcage Coil for Head Imaging at 4.7T MRI

This study analyzed asymmetrical designs of birdcage (BC) coils, for which the conventional shape of the BC is modified in order to improve field intensity and uniformity in the brain region for magnetic resonance imaging (MRI) at 4.7T. Typically the BC coil has insufficient field uniformity when operating at higher frequencies such as 200 MHz, corresponding to the Larmor frequency at 4.7T, due to the interaction between the electrical properties of body tissue and the propagated magnetic field wavelength. We propose a new design of BC coil, which consists of different ring diameters and leg width. The performance of proposed designs was compared to that of a body-size BC coil. Using finite-difference time-domain simulations to obtain the |B1 +| fields for a human model, we demonstrate that the proposed designs can achieve better field intensity and uniformity compared with other BC coil designs.