Fast and pseudo-random: optimization of settings for rapid quantification of T1 in white and grey matter at 64 mT

Motivation: Low-field MRI holds promise for efficient diagnostics. T1 mapping is valuable in neuroscience for studying myelination and brain development. To reduce scan time, incoherent, variable density trajectories are often used. Goal(s): to reach high image quality and T1 accuracy for fast T1 mapping at 64 mT. Approach: Using the 64-mT, Hyperfine Swoop scanner, we compared T1 maps acquired with fully sampled and undersampled trajectories (with and without incoherence) and reconstructed them with locally low rank regularization at different regularization factors λ. Results: Our findings showed that the most effective approach involves the use of a customized trajectory with λ around 0.004. Impact: Since fast and accurate T1 mapping in the context of low-field MRI is achievable, it would now be interesting to study brain developement in children, that present a unique challenge due to movement.