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MRI of normal brain maturation
Insights
Magnetic resonance imaging (MRI) reveals how brain myelination develops in children. This study tracked myelination changes in 59 children, showing rapid development in early years and full maturation in adolescence.
Area of Science:
- Neuroscience
- Radiology
- Pediatric Imaging
Background:
- Magnetic resonance imaging (MRI) offers unprecedented gray/white matter differentiation.
- This capability allows for detailed tracing of normal myelination processes.
Purpose of the Study:
- To investigate and characterize the normal process of brain myelination in children using MRI.
- To establish age-related quantitative and qualitative changes in myelination.
Main Methods:
- Studied 59 children aged from term (40 weeks intrauterine) to 16 years using MRI with spin-echo technique.
- Measured T1 and T2 relaxation times in 13 regions of interest for 37 children.
- Qualitatively reviewed MRI scans for age-related changes in brain appearance.
Main Results:
- Observed a sharp decrease in T1 and T2 relaxation times with age, most significant in the first year, correlating with decreased water content and increased myelination.
- Identified rapid myelination during the first 2-3 years of life.
- Demonstrated earliest myelination in the posterior fossa, with major white matter tracts defined by 1 year, and adult brain configuration by early adolescence.
Conclusions:
- MRI provides a valuable tool for visualizing and understanding pediatric brain development and myelination.
- Myelination is a dynamic process occurring predominantly in early childhood, with gradual maturation into adolescence.
Abstract:
The unprecedented gray/white differentiation obtained with magnetic resonance imaging (MRI) has created a unique opportunity to trace the normal process of myelination. Fifty-nine children referred for evaluation of a nonneurologic problem or a nonspecific neurologic complaint were studied with MRI using spin-echo technique. Children ranged in age from term (40 weeks intrauterine) to 16 years. Scans were reviewed for quantitative and qualitative changes with age. T1 and T2 relaxation times were measured for 13 regions of interest in 37 children. With increasing age a sharp decrease in both T1 and T2 values, most pronounced during the first year of life, was seen. The prolonged relaxation times in the newborn infant correspond to the known high water content of the neonatal brain; the subsequent decline corresponds to the decrease in water content and increase in myelination observed in autopsy studies of infants. Qualitative changes in the MRI appearance of the brain with age using a spin-echo sequence (2 sec repetition time) demonstrated that the process of myelination was most rapid during the first 2-3 years of life. Myelination appeared to occur earliest in the posterior fossa, with the middle cerebellar peduncle identifiable at only 3 months. By the age of 1 year, all major white matter tracts including the corpus callosum, subcortical white matter, and the internal capsule were well defined. However, due to subtle changes in appearance, the refined configuration of the adult brain was not attained until early adolescence.