Fixel-based analysis in very preterm infants before term age: associations with postmenstrual age
Poster No:
304
Submission Type:
Abstract Submission
Authors:
Kerstin Pannek1, Roslyn Boyd2, Joanne George3, DanaKai Bradford1, Atul Malhotra4, Paul Colditz5, Jurgen Fripp1
Institutions:
1CSIRO, Brisbane, Australia, 2The University of Queensland, Brisbane, Australia, 3Queensland Children's Hospital, Brisbane, Australia, 4Monash University, Melbourne, Australia, 5Royal Brisbane and Women's Hospital, Brisbane, Australia
First Author:
Co-Author(s):
Introduction:
Infants born preterm are at an increased risk of adverse neurodevelopmental outcomes. To facilitate early prediction of outcomes, a greater understanding of normal and abnormal brain development is needed. The purpose of this work was to assess ongoing brain maturation using fixel-based analysis (Raffelt et al., 2017) in the preterm period in a cohort of very preterm infants with minimal brain abnormality on conventional imaging. Based on previous work (Pannek et al., 2018) we expected fixel measures to be positively associated with postmenstrual age (PMA) at MRI throughout the white matter. Additionally, we expected fibre density (FD) to be negatively associated with PMA in the cortical gray matter.
Methods:
Infants born <31 weeks' gestation (n=131) underwent multi-shell diffusion imaging between 29 and 35 weeks PMA. T2-weighted HASTE and T1-weighted TSE/FLASH images were scored for brain growth and abnormality (Kidokoro et al., 2013; George et al., 2017). White matter myelination delay was set to 'normal' for all subjects as myelination is not commonly evident at this age. Of 131 infants, 75 infants were classified as having no brain abnormality, with diffusion imaging of 68 successfully preprocessed for fixel-based analysis (35 male; median gestation at birth 29+3 weeks, range 25+3 - 30+6 weeks; median PMA at MRI 32+0 weeks, range 29+6 - 34+5 weeks). Associations between PMA at the time of MRI and fibre density (FD), log fibre-bundle cross-section (logFC) and fibre density and bundle cross-section (FDC) were investigated. Analysis of logFC and FDC were adjusted for total intracranial volume.
Results:
Associations between fixel measures and PMA were found throughout the brain (Figure 1). As expected, FD was positively associated with PMA in the middle cerebellar peduncle, left occipital lobe and small sections of the left corticospinal tract; logFC was positively associated with PMA in the bilateral posterior limb of the internal capsule, precentral gyrus and cerebellum; and FDC was positively associated with PMA in the bilateral corticospinal tracts and the cerebellum. Furthermore, as expected there were widespread negative associations between FD and PMA in the cortical gray matter. Interestingly, FD was also negatively associated with PMA in the anterior corpus callosum, and the right cingulum bundle; logFC was negatively associated with PMA in the bilateral superior longitudinal fasciculus, genu and splenium of the corpus callosum; and FDC was negatively associated with PMA in the anterior corpus callosum, the left occipital white matter, and frontal cortical gray matter. Single-fixel post-hoc analysis results are presented in Figure 2.
Conclusions:
Our preliminary findings indicate that the corticospinal tracts and cerebellar tracts undergo rapid macrostructural development relative to total brain growth in the time period under assessment, while SLF, CC genu and CC splenium growth is slower than total brain growth in this period. The negative association between FD and PMA in cortical gray matter likely reflects decreases in the radial organisation of the cortex in this time period. Post hoc analysis of a single fixel within the right SLF indicates that this area shows no evidence of growth over the assessed time period. These results contrast with prior findings at term equivalent age, where widespread positive associations with PMA were found throughout the white matter for all three fixel metrics (Pannek et al., 2018). Future research will investigate associations with PMA both before and around term equivalent age in the same infants to determine whether associations with PMA are different between those time periods, contrast infants with and without brain abnormality on conventional imaging and assess associations with neurodevelopmental outcomes.
Disorders of the Nervous System:
Neurodevelopmental/ Early Life (eg. ADHD, autism) 1
Lifespan Development:
Early life, Adolescence, Aging
Normal Brain Development: Fetus to Adolescence
Modeling and Analysis Methods:
Diffusion MRI Modeling and Analysis 2
Keywords:
Development
MRI
PEDIATRIC
WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
1|2Indicates the priority used for review
Abstract Information
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Provide references using APA citation style.
Kidokoro, H., Neil, J. J., & Inder, T. E. (2013). New MR Imaging Assessment Tool to Define Brain Abnormalities in Very Preterm Infants at Term. American Journal of Neuroradiology, 34(11), 2208–2214. https://doi.org/10.3174/ajnr.A3521
Pannek, K., Fripp, J., George, J. M., Fiori, S., Colditz, P. B., Boyd, R. N., & Rose, S. E. (2018). Fixel-based analysis reveals alterations in brain microstructure and macrostructure of preterm-born infants at term equivalent age. NeuroImage. Clinical, 18, 51–59. https://doi.org/10.1016/j.nicl.2018.01.003
Raffelt, D. A., Tournier, J. D., Smith, R. E., Vaughan, D. N., Jackson, G., Ridgway, G. R., & Connelly, A. (2017). Investigating white matter fibre density and morphology using fixel-based analysis. NeuroImage, 144, 58–73. https://doi.org/10.1016/j.neuroimage.2016.09.029