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NORMAL MYELINATION BY MR
Myelination of the brain during infancy progresses in an orderly and predictable fashion.
At birth only certain structures are myelinated:
- dorsal brainstem
- ventrolateral thalamus
- lentiform nuclei
- central corticospinal tracts
- posterior limb of the internal capsule
- middle cerebellar peduncle
- optic nerve, chiasma and tract
Subsequently different parts become myelinated, the first change is increase in T1 signal, and later decrease in T2.
- 2-3 months: anterior limb of internal capsule becomes T1 bright
- 3 months: cerebellar white matter tracts becomes T1 bright
- 3-6 months: splenium of corpus callosum becomes T2 dark
- 6 months: genu of corpus callosum becomes T1 bright
- 8 months: subcortical white matter becomes T1 bright
- 8 months: genu of corpus callosum becomes T2 dark
- 11 months: anterior limb of internal capsule becomes T2 dark
- 1 year 2 months: occipital white matter becomes T2 dark
- 1 year 4 months: frontal white matter becomes T2 dark
- 1 1/2 years: majority of white matter becomes T2 dark (except terminal myelination zones adjacent to frontal horns and periatrial regions)
- 2 years: almost all of white matter becomes T2 dark
Superintendent, ICH.