Eight-Channel Tx/Rx Helmet Coil for Human Brain Imaging with Improved RF Homogeneity

Wolfgang Driesel¹, Toralf Mildner¹, Andr Pampel¹, Harald E. Mller¹

Two versions of an anatomically shaped microstrip transmission-line (MTL) helmet coil were built: (A) a circularly polarized (CP) transmit/receive (Tx/Rx) coil and (B) a CP-Tx/eight-channel-Rx array. Curved MTL elements of different lengths were used to provide sufficient space for audiovisual stimulation and the electrical length was adjusted by proper termination. Both helmet coils generated an almost perfect circular polarization in a large portion of the human head extending into regions near the coil elements. Initial experiments verify that the designs permit imaging of the brain with good tissue contrast and potential for parallel imaging.