TL;DR: Brain morphometry at 64mT (= 0.064T) is very much feasible. Perhaps most interesting is the fact that the dataset -> ~ T1w & T2w scans x (4 resolutions x 2 Hyperfine Swoop 64 mT scanners + GE 3T scanner) x 23 adult participants = 390 scans -> is openly available: openneuro.org/datasets/ds0...
František Váša
New paper in Imaging Neuroscience by František Váša, Steven C.R. Williams, et al:
Ultra-low-field brain MRI morphometry: Test–retest reliability and correspondence to high-field MRI
doi.org/10.1162/IMAG...
