Pediatric Radiology > Neurological > Developmental Abnormalities > Myelination Abnormalities

Myelination Abnormalities

During the first two years of life, there are great changes of myelination in the brain. Before myelination, white matter is hydrophilic and appears high in signal on T2 imaging and low signal on T1. With myelination, white matter becomes hydrophobic and becomes lower signal on T2 and higher on T1. The adult pattern of myelination is complete by 18 to 24 months and progresses in an expected pattern. It is interesting to note that brain maturation occurs at different rates and times on T1 and T2 weighted images. The exact reason is not understood. Myelination progresses from a caudal to cranial direction. Typically, before age 6 months, T1 weighted images are used to determine brain maturation. After 6 months of age, T2 weighted images are used.


Ages when changes on myelination appear on MRI

Anatomic Region T1 weighted image T2 weighted image
Middle cerebellar peduncle Birth Birth - 2 months
Cerebral white matter Birth - 4 months 3-5 months
Anterior portion of posterior limb of internal capsule 2-3 months 4-7 months
Posterior portion of posterior limb of internal capsule 4-6 months Birth - 2 months
Anterior limb of internal capsule 2-3 months 7-11 months
Genu corpus callosum 4-6 months 5-8 months
Splenium corpus callosum 3-4 months 4-6 months
Central occipital white matter 3-5 months 9-14 months
Peripheral occipital white matter 4-7 months 11-15 months
Central frontal white matter 3-6 months 11-16 months
Peripheral frontal white matter 7-11 months 14-18 months
Centrum semiovale 2-6 months 7-11 months


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