Diffusion MRI of white matter microstructure development in childhood and adolescence: Methods, challenges and progress

Abstract

Diffusion magnetic resonance imaging (dMRI) continues to grow in popularity as a useful neuroimaging method to study brain development, and longitudinal studies that track the same individuals over time are emerging. Over the last decade, seminal work using dMRI has provided new insights into the development of brain white matter (WM) microstructure, connections and networks throughout childhood and adolescence. This review provides an introduction to dMRI, both diffusion tensor imaging (DTI) and other dMRI models, as well as common acquisition and analysis approaches. We highlight the difficulties associated with ascribing these imaging measurements and their changes over time to specific underlying cellular and molecular events. We also discuss selected methodological challenges that are of particular relevance for studies of development, including critical choices related to image acquisition, image analysis, quality control assessment, and the within-subject and longitudinal reliability of dMRI measurements. Next, we review the exciting progress in the characterization and understanding of brain development that has resulted from dMRI studies in childhood and adolescence, including brief overviews and discussions of studies focusing on sex and individual differences. Finally, we outline future directions that will be beneficial to the field.

Magnetic Resonance Imaging in Pediatric Migraine

“…The diffusion signal is based on free diffusion of water, which is hindered by WM fibers. 28 DTI data enable maps depicting (a) the overall level of diffusion, typically shown as mean diffusivity (MD) and (b) the level of diffusion anisotropy or directionality associated with diffusion. Diffusion anisotropy is measured as: axial diffusivity (AD), the level of diffusion parallel to a WM tract; radial diffusivity (RD), diffusion across or perpendicular to the WM tract; and fractional anisotropy (FA), a composite where 1 is completely anisotropic diffusion (single orthogonal direction of diffusion) and 0 represents completely isotropic diffusion ( Figure 1).…”

White matter microstructure across the adult lifespan: A mixed longitudinal and cross-sectional study using advanced diffusion models and brain-age prediction

“…Age-related trajectories of white matter macro-and microstructure typically reflect increases in anisotropy and decreases in diffusivity during childhood, adolescence and early adulthood (Krogsrud et al, 2016;Tamnes et al, 2018;Westlye et al, 2010), and subsequent anisotropy decreases and diffusivity increase in adulthood and senescence (Cox et al, 2016;Davis et al, 2009). While the field has primarily been dominated by cross-sectional studies, which by design lack information on individual trajectories (Schaie, 2005), longitudinal studies in the last decade have shown corresponding white matter changes in both development and ageing (Barrick et al, 2010;Bender et al, 2016;Bender & Raz, 2015;de Groot et al, 2016;Likitjaroen et al, 2012;Racine et al, 2019;Sexton et al, 2014;Storsve et al, 2016;Teipel et al, 2010).…”

White matter plasticity and maturation in human cognition

“…Therefore, myelin structure is not imaged directly in humans, rather structure is inferred or modeled from nonspecific properties. Imaging of white matter has been recently reviewed comprehensively, so will not be covered in detail here (Lebel & Deoni, ; Lebel, Treit, & Beaulieu, ; Novikov, Fieremans, Jespersen, & Kiselev, ; Tamnes, Roalf, Goddings, & Lebel, ).…”

“…Diffusion MRI measures the random movement of water in the brain at the micron scale (Tamnes et al, ). Specifically, diffusion tensor imaging (DTI) models, the restriction and orientation of randomly moving water molecules in order to assess white matter structure.…”