Variable-flip-angle 3D spiral-in-out TSE/SPACE using echo-reordering and concomitant gradient compensation at 0.55 T

This study describes an alternative approach to Cartesian SPACE for 1 mm3 isotropic whole brain T2-weighted imaging on a high performance 0.55T scanner. In this technique, the Cartesian readouts were replaced by interleaved, rotated spiral-in-out trajectories, combined with a variable-flip-angle refocusing, echo-reordering, and concomitant gradient compensation. Parallel imaging (PI) and compressed sensing (CS) were utilized for further acceleration. Compared to 3D-Cartesian SPACE, this method can be leveraged to mitigate the lower SNR of 0.55T via the improved SNR efficiency of prolonged spiral trajectory sampling.