Simultaneous B1 and T1 mapping using spiral multislice variable flip angle acquisitions for whole-brain coverage in less than one minute

Purpose : Variable flip angle (VFA)-based T 1 quantification techniques are highly sensitive to B 1 inhomogeneities and to residual T 2 dependency arising from incomplete spoiling. Here, a rapid spiral VFA acquisition scheme with high spoiling efficiency is proposed for simultaneous whole-brain B 1 and T 1 mapping. Methods : VFA acquisitions at two different flip angles are performed to quantify T 1 using a steady-state prepared spiral 2D multislice spoiled gradient-echo sequence with the acquisition of 10 and 20 spiral interleaves at 1.5 T and 3 T, respectively. Additionally, parallel imaging acceleration of factor 2 is investigated at 3 T. The free induction decay induced by the preparation pulse is sampled by a single-shot spiral readout to quantify B 1 . Results : The in vitro and in vivo validations yielded good agreement between the derived spiral VFA B 1 and the acquired reference B 1 maps as well as between the B 1 -corrected spiral VFA T 1 and the reference T 1 maps. The spiral VFA acquisitions in the human brain delivered artifact-free B 1 and T 1 maps and demonstrated high reproducibility at 1.5 T and 3 T. Conclusion : Reliable simultaneous spiral VFA B 1 and T 1 quantification was feasible with acquisition times of less than one minute for whole-brain coverage at clinically relevant resolution.