A 7T spine array based on electric dipole transmitters

PURPOSE: The goal of this study was to explore the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high fields. METHOD: A two-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining eight loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared with a design using quadrature loop pairs. The radiofrequency energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies. RESULTS: The results indicate dramatically improved transmit efficiency for the dipole design compared with the loop excitation. A gain of up to 76% was achieved within the spinal region. CONCLUSION: For imaging of the spine, electric dipole-based transmitters provide an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high fields.