2. Brain Development: Myelination

Question 1

MRI pattern adult vs infant

Answer 1

The T1 pattern of a baby is similar to the T2 pattern of an adult.

The T2 pattern of a baby is similar to the Ti
pattern of an adult. This appearance is the result of myelination changes.

Question 2

The process of myelination

Answer 2

Immature myelin = higher water content = brighter on T2WI and Darker on T1WI

maturation = water will decrease = fat increases (cholesterol, glycolipids) = mature white matter = bright on T1/Dark T2

Question 3

MRI:

What changes first? T1 or T2?

Why is it important?

Answer 3

T1 changes precedes T2

Adult T1 at age 1
Adult T2 at age 2

(1 for T1, 2 for T2

T1 = Important for assessing myelination in the first year (0-6 months)

T2 = important for assessing myelination in the second year (6-18 months)

Question 4

Order of myelination

Answer 4

Inferior to superior
Posterior to anterior
Central to peripheral

Sensory fibers prior to motor fibers

So SUBCORTICAL white matter is the last part of the brain to myelinate - occipital 12 months - finishin around 18 months in the frontal

Terminal zones - 40 months

The brainstem, and posterior limb of the internal capsule are normally myelinated at birth

Inf-sup / Post frontal