Quantifying human gray matter microstructure using NEXI and 300 mT/m gradients

For the first time, we report Neurite Exchange Imaging (NEXI) microstructure model parameters estimates in human cortex in vivo. We also investigate the performance of two extensions of this model, the addition of a dot compartment and a correction for wide pulses. Parameter estimates are consistent with previous findings in the rat cortex in vivo. Importantly, NEXI estimates displayed good scan-rescan reproducibility while retaining sensitivity to inter-subject differences. Future work will focus on improving the precision, in particular of the exchange time estimates, possibly leveraging multi-dimensional diffusion MRI acquisitions.