Developmental features of the neonatal brain: MR imaging. Part I. Gray-white matter differentiation and myelination.

Abstract

To establish the normal appearance of the neonatal brain, 51 neonates, 29-42 weeks postconception, underwent magnetic resonance (MR) imaging with a 0.6-T magnet in a prospective study. T1-weighted images were used to devise stages for the appearance of gray-white matter differentiation and extent of myelination. The results show that from 29 to 42 weeks postconception, changes in gray-white matter differentiation and myelination follow the stages in an orderly and predictable fashion. Changes in white matter intensity appear related to progressive decrease in brain water content. Myelination progresses cephalad from the brain stem at 29 weeks to reach the centrum semiovale by 42 weeks. Delayed myelination, defined as the absence of myelin in the corona radiata by 37 weeks, was seen in nine infants with complicated perinatal courses. Awareness of these developmental features should help to minimize misinterpretation of normal changes in the neonatal brain and lead to earlier detection of pathologic conditions, both with MR imaging and computed tomography.

A quantitative measure of myelination development in infants, using MR images

“…The divergence of white and gray matter is most rapid in the first 3 years of development, a finding that fits well with the qualitative judgments in previous studies. Divergence values decreased in the direction from inferior to superior regions of the frontal lobe, indicating decreased levels of myelination, which is in agreement with previous findings [11,15]. Of interest is the finding that there are myelination differences between the cases with PVL and cases with no neurological findings.…”

“…Complementing this finding, our quantitative measures of MR signal differences are in agreement with the judgments of the stages of myelination relying on qualitative classifications by experts [9,10,11,12,13,14,15]. The divergence of white and gray matter is most rapid in the first 3 years of development, a finding that fits well with the qualitative judgments in previous studies.…”

“…Changes in MRI features are informative in determining the developmental changes in white and gray matter for normal and clinical cases [7,8]. Findings from qualitative studies show that myelination occurs earliest in the posterior fossa at 3 months postnatal, with well-defined white matter tracts including the corpus callosum appearing by the end of the first year, and continues development through adulthood [9,10,11,12,13,14,15,16,17]. In the first year after birth, water content of the brain decreases and white matter increases in myelin content.…”

“…Recent MR studies indicated that children 36-40 months show adult-like patterns [17]. In general, myelination proceeds in the posterior-to-anterior, inferiorto-superior, and central-to-peripheral directions [11,15].…”

Volumetric Neuroimaging of the Atlantic White‐Sided Dolphin (Lagenorhynchus acutus) Brain from in situ Magnetic Resonance Images

“…Immature white matter is composed of axons that do not contain myelin or mature myelin sheaths. Immature white matter displays a higher signal on T2-weighted images compared with mature white matter, with longer T2 relaxation times than those of the adult brain, predominantly due to the higher water content of immature white matter (Holland et al, 1986;McArdle et al, 1987;Barkovich et al, 1988). With increasing maturation of the brain, the white matter signal decreases on T2-weighted images.…”