The optimized double echo steady-state (DESS) sequence for T2w fluid attenuation contrast at 7T

Motivation: Three-dimensional high-resolution fluid attenuation inversion recovery (FLAIR) acquired using the SPACE sequence at 7T is challenging due to the SAR issue and B0 inhomogeneity. Goal(s): To optimize the DESS sequence for presenting a semi-FLAIR contrast Approach: The effect of the excitation FA and the spoiler gradient between the first (S_plus) echo and the second (S_minus) echo of the DESS was evaluated by EPG simulation and validated by the in vivo experiments. Results: The optimized DESS sequence (low FA of 8° and spoiler gradient) produces perfect fluid attenuation near the sphenoid sinus with a scan time of 6:30 min (0.64 mm iso). Impact: This study reported the first time the semi-FLAIR contrast at 7T without SAR limitation and B0 impact especially around sphenoid sinus using the low flip angle DESS sequence.