Controlling sharpness, SNR and SAR for 3D fast spin echo measurements at 7T by end-to-end learning

Motivation: To non-heuristically identify dedicated variable flip angles (VFAs) simultaneously optimized for PSF and/or SNR of multiple tissues in 3D FSE sequences with very long echo trains at 7T. Goal(s): Flexibly tune between VFAs which favor visibility of small structures (e.g. inner ear imaging), or enhanced signal magnitudes (e.g. low proton-density) Approach: End-to-end optimization which integrates contrast fidelity, SNR and PSF-penalty to minimize image blurring for multiple tissues. Results: PSF-optimization yields significantly reduced image blurring compared to standard T2w/FLAIR vendor sequences with pTx and echo train lengths of 220 while maintaining contrast fidelity. SNR-optimization yields strongly increased magnitudes at equal relative SAR. Impact: This work paves the way to the flexible tuning of the PSF- or SNR-like flavour of dedicated variable flip angles at 7T to enhance visibility of small stuctures or SNR in 3D fast spin-echo sequences with very long echo trains.