Investigation of a remote 32-channel whole-body coil for large field of view 1H body imaging at 7 T

This work aimed to evaluate the remote coil in comparison to existing local coils and to experimentally investigate the parallel transmit (pTx) capabilities of the remote coil through in-vivo measurements. The thesis was divided into two parts. First, the transmit and receive performance of seven different local pTx coils and the remote coil (also in combination with a dedicated local receive array) were quantitatively assessed through phantom measurements. The remote coil demonstrated the largest excitation coverage in head-foot direction. Although, its maximum B1+ efficiency at the isocenter was 2.0 times lower than that of local transmit-receive coils, this limitation could be compensated with the four- or eight-fold higher total available power. While the best performing local transmit-receive coil enabled higher acceleration factors than the dedicated local receive array, the latter achieved the highest signal-to-noise ratio in the phantom’s center. Second, the pTx capabilities of the remote coil were investigated through in-vivo measurements. The first study demonstrated homogeneous liver excitation using static pTx. The second in-vivo study extended the excitation region to the whole abdomen, where two kT-point pTx pulses were required for sufficient homogeneity across all subjects. In conclusion, the remote coil, combined with a dedicated local receive array, represents the state-of-the-art for body imaging at 7 T. These findings highlight its potential for large field-of-excitation imaging and its necessity for translating UHF body MRI into clinical practice.