Optimized ultrahigh field parallel transmission workflow using rapid presaturated TurboFLASH transmit field mapping with a three-dimensional centric single-shot readout

Purpose: To evaluate the usage of three-dimensional (3D) presaturated TurboFLASH (satTFL) for $B_1^{+}$ and $B_0$ mapping on single channel and parallel transmission (pTx) systems.

Methods: $B_1^{+}$ maps recorded with 3D satTFL were compared to maps from three other 3D $B_1^{+}$ mapping sequences in an agar phantom. Furthermore, individual-channel $B_1^{+}$ maps of 18 human subjects were recorded with 3D satTFL using $B_1^{+}$ interferometry. A neural network was trained for masking of the maps.

Results: Out of the sequences compared satTFL was the only one with a mapping range exceeding well over 90°. In regions with lower flip angles there was high correspondence between satTFL and AFI. DREAM and double angle method also showed high qualitative similarity, however the magnitude differed from the other two measurements. The individual-channel $B_1^{+}$ maps were successfully used for pTx pulse calculation in a separate study.

Conclusion: 3D satTFL can record high-quality $B_1^{+}$ maps with a high dynamic range in a short time. Correspondence with AFI maps is high, while measurement duration is reduced drastically.