Journal Article

Long-term development of white matter fibre density and morphology up to 13 years after preterm birth: A fixel-based analysis

Cheong, Jeanie LY, Thompson, Deanne K., Genc, Sila, Adamson, Chris, Doyle, Lex W., Beare, Richard, Chen, Jian, Seal, Marc L., Kelly, Claire E., Yang, Joseph YM, Anderson, Peter J.

2020

Overview

It is well documented that infants born very preterm (VP) are at risk of brain injury and altered brain development in the neonatal period, however there is a lack of long-term, longitudinal studies on the effects of VP birth on white matter development over childhood. Most previous studies were based on voxel-averaged, non-fibre-specific diffusion magnetic resonance imaging (MRI) measures, such as fractional anisotropy. In contrast, the novel diffusion MRI analysis framework, fixel-based analysis (FBA), enables whole-brain analysis of microstructural and macrostructural properties of individual fibre populations at a sub-voxel level. We applied FBA to investigate the long-term implications of VP birth and associated perinatal risk factors on fibre development in childhood and adolescence. Diffusion images were acquired for a cohort of VP (born <30 weeks’ gestation) and full-term (FT, ≥37 weeks’ gestation) children at two timepoints: mean (SD) 7.6 (0.2) years (n ​= ​138 VP and 32 FT children) and 13.3 (0.4) years (n ​= ​130 VP and 45 FT children). 103 VP and 21 FT children had images at both ages for longitudinal analysis. At every fixel (individual fibre population within an image voxel) across the white matter, we compared FBA metrics (fibre density (FD), cross-section (FC) and a combination of these properties (FDC)) between VP and FT groups cross-sectionally at each timepoint, and longitudinally between timepoints. We also examined associations between known perinatal risk factors and FBA metrics in the VP group. Compared with FT children, VP children had lower FD, FC and FDC throughout the white matter, particularly in the corpus callosum, tapetum, inferior fronto-occipital fasciculus, fornix and cingulum at ages 7 and 13 years, as well as the corticospinal tract and anterior limb of the internal capsule at age 13 years. VP children also had slower FDC development in the corpus callosum and corticospinal tract between ages 7 and 13 years compared with FT children. Within VP children, earlier gestational age at birth, lower birth weight z-score, and neonatal brain abnormalities were associated with lower FD, FC and FDC throughout the white matter at both ages. VP birth and concomitant perinatal risk factors are associated with fibre tract-specific alterations to axonal development in childhood and adolescence. •We present a fixel-based analysis in preterm-born children relative to controls.•Preterms have widespread fibre density and cross-section reductions at age 7 and 13.•Longitudinally, preterms have slower development of commissural and motor fibres.•Gestational age, birth weight and brain abnormalities relate to fibre alterations.

• Publisher: Elsevier Inc,Elsevier Limited,Elsevier
• Subject: Adolescent / Adolescents / Anisotropy / Axonogenesis / Birth weight / Brain - diagnostic imaging / Brain - growth & development / Brain injury / Child / Child development / Children / Cingulum / Corpus callosum / Diffusion imaging / Diffusion Magnetic Resonance Imaging / Female / Fornix / Gestational age / Hospitals / Humans / Infants / Longitudinal / Longitudinal Studies / Magnetic Resonance Imaging / Male / Microstructure / Neonates / Nerve Fibers, Myelinated / Neuroimaging / Premature birth / Premature Birth - diagnostic imaging / Prematurity / Pyramidal tracts / Risk factors / Substantia alba / Traumatic brain injury / White matter / White Matter - diagnostic imaging / White Matter - growth & development