Combining multi-gradient-echo (MGRE) acquisitions with inversion/saturation preparation pulses allows for separation of white matter signal in several water compartments and estimation of both their T1 and exchange properties. A model of multiple myelin, myelin water and axonal/interstitial water compartments was implemented, including exchange from and across individual lipid bi-layers. Fitting this model to the inversion prepared MGRE-data resulted in T1's and exchange rates for all compartments. The results from a corpus-callosum region of interest indicate that the single layer myelin water residence time is a few hundred microseconds, while the average residence time of all myelin water combined is around 15ms.
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