RF shimming for improved B1+ in the carotid arteries using parallel transmission (pTx) head coils at 7T

Cerebrovascular imaging methods suffer from a rapid drop in B1+ into the neck when using typical transmit head coils at 7T. Custom RF shims on regular pTx head coils could improve the B1+ magnitude in the major feeding arteries in the neck region over standard CP transmit mode. We found that this can improve the B1+ magnitude in the carotid arteries by 36% while also improving the RF homogeneity. This can be achieved using universal, phase-only RF shims, facilitating easy implementation in existing sequences and without requiring custom hardware.