Towards Combined Brain and Cervical Spine Imaging at 7 T with an 8-channel pTx Coil: The Importance of Accurate B1+ Maps for Dynamic pTx

Motivation: Current combined brain and cervical spine pTx coils at 7 Tesla require more than eight transmit (Tx) channels, limiting their widespread use. Goal(s): To investigate wether a pTx coil with eight Tx elements and tailored and universal pTx achieves uniform flip-angles (FA) simulataneously across the brain and cervical spine regions. Approach: Simulated B1+ maps were calculated for the Duke and Ella models. Tailored phase-only RF shims and dynamic kT-points pulses were optimized for FA homogeneity. Results: Dynamic tailored/universal kT-points pulses significantly improved FA homogeneity over RF shimming (5/2.5x for 5-kT-points). Accurate B1+ information is crucial for optimal FA homogeneity in dynamic pTx. Impact: This simulation study demonstrates feasability of combined brain and cervical spine MRI at 7 Tesla using an eight Tx channel dynamic pTx setup. Optimized pTx pulses result in high FA homogeneity and enable detailed investigations of both neuroanatomical structures simultaneously.