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Age-related changes in the pediatric brain: quantitative MR evidence of maturational changes during adolescence
R G Steen1, R J Ogg, W E Reddick
1Department of Diagnostic Imaging, St Jude Children's Research Hospital, University of Tennessee School of Medicine, Memphis 38105-2794, USA.
Insights
Quantitative MR imaging maps spin-lattice relaxation time (T1) to characterize brain maturation. T1 values decrease with age in various brain structures, with white matter maturing faster than gray matter.
Area of Science:
- Neuroimaging
- Developmental Neuroscience
- Quantitative MRI
Background:
- Brain maturation involves complex structural and functional changes.
- Conventional MRI contrast may not fully capture subtle maturational differences.
- Quantitative MRI offers a method to assess tissue properties like spin-lattice relaxation time (T1).
Purpose of the Study:
- To evaluate the utility of quantitative magnetic resonance (MR) imaging for mapping spin-lattice relaxation time (T1).
- To characterize age-related maturational changes in the normal human brain using T1 mapping.
Main Methods:
- Employed an inversion-recovery technique to map T1 values.
- Studied healthy children, adolescents, and adults across different age groups.
- Acquired T1 maps at the level of the basal ganglia.
Main Results:
- T1 values significantly decreased with age across multiple brain regions, including gray and white matter.
- Significant T1 reductions were observed between childhood and adolescence, and adolescence and adulthood.
- White matter structures showed T1 values reaching adult ranges earlier than gray matter structures.
Conclusions:
- Quantitative T1 mapping effectively characterizes brain maturation.
- Brain structures mature at distinct rates, with white matter maturation preceding gray matter.
- Normative T1 data are crucial for pediatric disorder studies and assessing developmental delay.
Purpose:
To determine whether a quantitative MR imaging method to map spin-lattice relaxation time (T1) can be used to characterize maturational changes in the normal human brain.
Methods:
An inversion-recovery technique was used to map T1 transversely at the level of the basal ganglia in a study population of 19 healthy children (4 to 10 years old) and 31 healthy adolescents (10 to 20 years old), and in a normative population of 20 healthy adults (20 to 30 years old).
Results:
Nonparametric analysis of variance showed that T1 decreases with age in the genu, frontal white matter, caudate, putamen, anterior thalamus, pulvinar nucleus, optic radiation, cortical gray matter (all P < .0001), and occipital white matter. There was a significant reduction in T1 between childhood (mean age, 7.1 +/- 1.4) and adolescence (mean age, 13.5 +/- 2.6) in all brain structures, but there was also a significant reduction in T1 between adolescence (mean age, 13.5 +/- 2.6) and adulthood (mean age, 26.5 +/- 3.4) in all brain structures except occipital white matter. Regression shows that T1 declines to within the range (mean +/- 2 SD) of young adult T1 values by about 2 years in the occipital white matter, by about 4 years in the genu, by 11 years in the cortical gray matter, by 11 years in the frontal white matter, and by 13 years in the thalamus.
Conclusion:
Brain structures mature at strikingly different rates, yet the ratio of gray matter T1 to white matter T1 does not change significantly with age. Thus, conventional MR imaging methods based on inherent contrast are insensitive to these changes. Age-related changes tend to reach completion sooner in white matter than in gray matter tracts. Such normative data are essential for studies of specific pediatric disorders and may be useful for assessing brain maturation in cases of developmental delay.