Scalable spokes pTx pulses for 2D turbo-spin-echo imaging at 7T

Motivation: At 7T, slice-by-slice 2D turbo-spin-echo (TSE/RARE/FSE) images are needed for clinical protocols, but show strong signal drop-outs in single transmit scans. Goal(s): Our goal is to acquire high-fidelity 2D TSE images across the whole brain using parallel transmit. Approach: PTx pulses must satisfy the Carr-Purcell-Meiboom-Gill (CPMG) conditions for good image quality. We achieve this using novel slice-selective scalable spokes pTx pulses. Results: Simulations and phantom scans show that 3-spoke scalable pulses have high flip-angle uniformity and maintain consistent phase profiles. In vivo tests show uniform images across the whole brain including in temporal lobes. VOP SAR supervision is needed for optimum TR. Impact: Scalable spokes pTx pulses produce high quality 2D-TSE images. It mitigates signal dropouts and recover diagnostic quality when single-transmit scans are inadequate. This will be valuable for patients with drug-resistant focal epilepsy to find epilepsy-causing lesions in the temporal lobes.