biostudies-literatureUnknown228(2)Sandrone SEuropean Research CouncilNational Institute for Health Research (NIHR)Sackler Institute for Translational Neurodevelopment, King's College LondonWellcome TrustThe ratio of T1-weighted/T2-weighted magnetic resonance images (T1w/T2w MRI) has been successfully applied at the cortical level since 2011 and is now one of the most used myelin mapping methods. However, no reports have explored the histological validity of T1w/T2w myelin mapping in white matter. Here we compare T1w/T2w with ex vivo postmortem histology and in vivo MRI methods, namely quantitative susceptibility mapping (QSM) and multi-echo T2 myelin water fraction (MWF) mapping techniques. We report a discrepancy between T1w/T2w myelin maps of the human corpus callosum and the histology and analyse the putative causes behind such discrepancy. T1w/T2w does not positively correlate with Luxol Fast Blue (LFB)-Optical Density but shows a weak to moderate, yet significant, negative correlatioBrain structure & function525-535https://www.ebi.ac.uk/biostudies/studies/S-EPMC9944377biostudies-literatureMapping myelin in white matter with T1-weighted/T2-weighted maps: discrepancy with histology and other myelin MRI measures.PMC9944377Aiello MCavaliere CTroakes CMurphy DSandrone SThiebaut de Schotten MReimann KBodi ICatani MGeyer SMonti SDell'Acqua FLacerda LfalseMapping myelin in white matter with T1-weighted/T2-weighted maps: discrepancy with histology and other myelin MRI measures.The ratio of T1-weighted/T2-weighted magnetic resonance images (T1w/T2w MRI) has been successfully applied at the cortical level since 2011 and is now one of the most used myelin mapping methods. However, no reports have explored the histological validity of T1w/T2w myelin mapping in white matter. Here we compare T1w/T2w with ex vivo postmortem histology and in vivo MRI methods, namely quantitative susceptibility mapping (QSM) and multi-echo T2 myelin water fraction (MWF) mapping techniques. We report a discrepancy between T1w/T2w myelin maps of the human corpus callosum and the histology and analyse the putative causes behind such discrepancy. T1w/T2w does not positively correlate with Luxol Fast Blue (LFB)-Optical Density but shows a weak to moderate, yet significant, negative correlatio2023-01-01T00:00:00Z2023 Mar2025-04-04T18:59:57.796Z2025-02-19T03:59:37.18ZS-EPMC99443773669269510.1007/s00429-022-02600-z