Poster No:
1301
Submission Type:
Abstract Submission
Authors:
Fumitaka Homae1, Daisuke Tsuzuki2
Institutions:
1Tokyo Metropolitan University, Tokyo, 2Kochi University, Kochi
First Author:
Co-Author:
Introduction:
The cerebral cortex exhibits a thicker profile at convex regions, such as the crown near the vertices of cortical gyri, compared to concave regions at the fundi of cortical sulci. This tendency has been observed in adults through structural magnetic resonance imaging (MRI) measurements (Fischl & Dale, 2000), neonates, and infants (Holland et al., 2020). The difference between convex and concave regions is also evident in their degree of myelination, as measured by quantitative relaxation rate mapping (Sereno et al., 2013) and in the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images (Shafee et al., 2015). Since not all sulci and gyri are fully matured at term, we anticipate that cortical thickness and the degree of myelination will vary based on the morphological changes of the cortical surface during early infancy.
Methods:
In this study, we parameterized the local shape of the cortical surface and examined the profiles of cortical thickness in convex and concave regions relative to gestational age. We analyzed infant MRI data from the second release of the Developing Human Connectome Project (Hughes et al., 2017). The dataset included brain images of preterm and full-term infants (N = 401; range of the scans: 37.0–44.7 gestational weeks). Each infant was classified into eight groups based on the scan week, ranging from 37 to 44 weeks. The database provided cortical mesh data reconstructed from structural MRIs. Cortical thickness was defined as the distance between pial and white-matter surfaces (Bozek et al., 2018; Makropoulos et al., 2018). The values of T1w/T2w at each vertex of the surface mesh were also utilized in the analysis. We calculated the principal curvatures at each vertex and determined vertex-wise shape indexes (Koenderink & Van Doorn, 1992). Based on the shape index, vertices were categorized into one of seven morphological definitions: spherical cup, rut, saddle rut, saddle, saddle ridge, ridge, and dome (Vezzetti & Marcolin, 2012). The spherical cup and dome categories predominantly appeared in the sulcal fundi and gyrus crowns, respectively. For each infant, we obtained the mean values of cortical thickness and T1w/T2w across vertices within each morphological category.
Results:
The cortical thickness and T1w/T2w values increased with gestational weeks. At 44 weeks, the cortical thickness increased gradually from the spherical cup regions (lowest) to the dome regions (highest thickness). However, in full-term infants younger than 39 gestational weeks at MRI scanning, the cortical thickness in the dome regions was lower than in the ridge and saddle ridge regions. Furthermore, at around 40 weeks, preterm infants had a thicker cortex than full-term infants. Conversely, the T1w/T2w values showed the opposite trend; the values were higher in full-term infants than in preterm infants. In both infant groups, the spherical cup regions exhibited the lowest T1w/T2w values.
Conclusions:
These results suggest that the cortical thickness changes with the formation of cortical sulci and gyri and that its distribution depends on the gestational age at birth. Furthermore, the differences between the infant groups suggest that the cerebral cortex in preterm infants at approximately 40 gestational weeks contained relatively large amounts of astrocytes and extracellular matrix.
Lifespan Development:
Normal Brain Development: Fetus to Adolescence 1
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
Normal Development 2
Keywords:
STRUCTURAL MRI
Other - gyrus; sulcus; neonate
1|2Indicates the priority used for review
Provide references using author date format
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Koenderink, J. J. (1992). Surface shape and curvature scales. Image and vision computing, 10(8), 557-564.
Makropoulos, A. (2018). The developing human connectome project: A minimal processing pipeline for neonatal cortical surface reconstruction. Neuroimage, 173, 88-112.
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