Multi‐gradient‐echo myelin water fraction imaging: Comparison to the multi‐echo‐spin‐echo technique

Purpose Myelin water fraction (MWF) mapping based on multi‐gradient recalled‐echo (MGRE) imaging has been proposed as an alternative to the conventional multi‐echo‐spin‐echo (MESE) approach. In this work, we performed a comparative study of MESE and MGRE‐derived MWFs in the same subject group. Methods MESE and MGRE data were acquired in 12 healthy volunteers at 3T. decay curves were corrected for the effects of field inhomogeneities and multicomponent analysis of and signals was performed using non‐negative least‐squares fitting. Results When comparing MGRE and MESE‐MWFs across volunteers, no significant differences were observed between average values in WM, deep GM (dGM), and cortical GM (cGM) that were (14 ± 3%), (6 ± 2%), and (8 ± 2%) for MGRE, and (13 ± 2%), (6 ± 1%), and (7 ± 1%), respectively, for MESE. The MGRE and MESE‐MWFs showed a strong correlation (r 2 = 0.84) and Bland‐Altman analysis revealed a small positive bias of (0.8 ± 1.6%) (absolute difference) for the MGRE‐MWF. Conclusion Overall, we observed excellent agreement between the two techniques. The small positive bias of the MGRE‐MWF is thought to be a consequence of its potentially reduced sensitivity to water exchange effects, compared to the MESE‐MWF. This work suggests that with careful correction for the effects of field inhomogeneities, MGRE‐MWF imaging is a promising alternative to the MESE approach. Magn Reson Med 79:1439–1446, 2018. © 2017 International Society for Magnetic Resonance in Medicine.