Optimising magnetisation preparation for the 7T FLAIR contrast: simulations and experimental validation

Motivation: At ultra-high field, magnetisation preparation should be adjusted to obtain an adequate FLAIR contrast. However, such optimisation of the pulse sequence and comparison between preparation types are missing. Goal(s): This work aimed to set a simulation framework to investigate the timing of the magnetisation preparation at 7T. T2 and double inversion recovery preparations were compared. Approach: Various preparation durations were investigated using simulations and measurements on healthy volunteers. Results: The image contrast obtained under simulation was experimentally validated. The T2-preparation gave the most promising contrast although the pulses were more prone to B0-inhomogeneity artefacts than the ones from the double inversion recovery preparation. Impact: We demonstrated that an adequate FLAIR contrast at 7T can be obtained by optimising magnetisation preparation. Simulations can be used to improve the sequence, such as optimising the magnetisation preparation and readout in terms of timings and flip angles.