Quantitative myelin imaging with MPnRAGE‐derived R1 mapping: Applications to Alzheimer’s disease

Post‐mortem observations of Alzheimer’s disease (AD) brain suggest that developmental patterns of myelin and AD pathology are inversely related (Braak and Braak, 1996). Myelin injury and repair processes have also been implicated in the amyloid cascade hypothesis (Bartzokis, 2004; Depp et al., 2021). While diffusion‐weighted imaging has been widely applied to examine white matter abnormalities in AD, there remains a dearth of high resolution and high contrast imaging methods that allow for accurate and precise measurement of brain myelin in vivo. Here, we leveraged a novel imaging sequence—MPnRAGE (Kecskemeti et al., 2016; 2018)—to derive R1 maps, a myelin sensitive metric, and assessed the potential of R1 to identify myelin abnormalities in relation to cognitive impairment in AD.