Normal development of brain myelin sheath in children

*Zhang Jinling Jin Cuicui Zhao Deli

The Sixth Affiliated Hospital of Harbin Medical University

The Sixth Affiliated Hospital of Harbin Medical University

*The Second Affiliated Hospital of Harbin Medical University

*The Second Affiliated Hospital of Harbin Medical University

 

Magnetic resonance imaging is the best non-invasive way to assess brain myelination
.

Conventional T1 and T2 weighting is a sequence necessary for assessment of central nervous system myelination

diagnosis

 

Figure 1.
Schematic diagram of myelin sheath

Figure 1.
Schematic diagram of myelin sheath

 

Myelin sheath is an important part of neurons.
The myelin sheath envelops axons and is divided into segments by Langfei knots (Figure 1)
.

 

Figure 2.
Characteristics of myelin formation process

Figure 2.
Characteristics of myelin formation process

The formation of myelin is a dynamic process.
The maturation and myelination of the white matter of the brain are in sequence.
The order of myelination of the white matter is from the caudal side to the head side of the brain, and from the dorsal side to the ventral side.
, First from the center to the periphery, the sensory fiber is earlier than the sports fiber (Figure 2)
.

 

Figure 3A.
Myelinated structure at birth (T1)

Figure 3A.
Myelinated structure at birth (T1)

Figure 3B.
Myelinated structure at birth (T2)

 

Newborns have been myelinated structures at birth, showing T1 high signal T2 low signal (Figure 3A, B), including the hind limbs of the internal capsule, the ventrolateral thalamus, the dorsal side of the pons, the upper and lower feet of the cerebellum, the feet of the brain, and the center of the radiating crown , Central back to the surrounding area
.

 

Figure 4.
Myelin sheath in a child at 4 months

Figure 4.
Myelin sheath in a child at 4 months

Image of myelin sheath in a child at 4 months
.

At 4 months, slight hyperintensity on the T1 of the forelimb of the internal capsule, thickening of the myelin sheath in the central radial crown and semi-oval center, and myelination of the pressure part of the corpus callosum

 

Figure 5.
Myelin sheath in children at 6 months

Figure 5.
Myelin sheath in children at 6 months

Image of myelin sheath in a child at 6 months
.

At 6 months, the myelin sheath in the central white matter, especially in the half-egg center and the radiating corona area, has a large increase

 

Figure 6.
Myelin sheath in a child at 9 months

Figure 6.
Myelin sheath in a child at 9 months

Image of myelin sheath in a child at 9 months
.

At 9 months, the T2 myelin white matter signal gradually decreased, and T2 myelination was seen in the forelimbs of the internal capsule

 

Figure 7.
Myelin sheath in children at 12 months

Figure 7.
Myelin sheath in children at 12 months

Image of myelin sheath in a child at 12 months
.

At 12 months, T1 myelination was basically completed.

 

Figure 8.
Myelin sheath (T1) in a child at 18 months

Figure 8.
Myelin sheath (T1) in a child at 18 months

Image of T1 myelin sheath in a child at 18 months
.

At 18 months, T1 myelin sheath was intact, and the appearance was similar to that at 12 months

 

Figure 9.
Myelin sheath (T2) in a child at 18 months

Figure 9.
Myelin sheath (T2) in a child at 18 months

T2 myelin sheath in children at 18 months
.

T2 has almost complete myelination, except for the subfrontal lobe and temporal lobe, as well as the peripheral myelin terminal area, as shown in Figure 9

 

Figure 10.
Myelin sheath in a 2-year-old child

Figure 10.
Myelin sheath in a 2-year-old child

Image of myelin sheath in a 2-year-old child
.

At the age of 2 years, myelination on T1 and T2 is complete, and some T2 hyperintensity may remain in the lateral ventricle, inferior frontal lobe, and temporal lobe (Figure 10)

 

Figure 11.
Myelin sheath in a 3-year-old child

Figure 11.
Myelin sheath in a 3-year-old child

Image of myelin sheath in a 3-year-old child
.
At 3 years old, on T1-weighted and T2-weighted sequences, the myelin sheath is intact and has an adult-like appearance (Figure 11)
.

 

Figure 12.
Axial and coronal T2-weighted sequence showing normal myelin terminal zone

Figure 12.
Axial and coronal T2-weighted sequence showing normal myelin terminal zone

The axial and coronal T2-weighted sequences show the normal myelin terminal zone (black arrow)
.
These areas are usually located in the area around the posterior ventricle and the subcortical area of ​​the frontotemporal lobe (Figure 12)
.

 

Memory control card 1: Myelination of the corpus callosum

Memory control card 1: Myelination of the corpus callosum

Image of myelination of the corpus callosum
.
The sagittal T1-weighted sequence shows the normal development of the corpus callosum
.
(B) 4 months; (C) 6 months; (D) 16 months (see memory card 1)
.

 

Memory control card 2: T2 normal myelination progression

Memory control card 2: T2 normal myelination progression

T2 normal myelination progresses
.
T2-weighted sequence of MR imaging from birth (full-term newborn) to 2 years of normal myelination (see memory card 2)
.

 

Memory control card 3: T1 normal myelination progression

Memory control card 3: T1 normal myelination progression

T1 normal myelination progresses
.
T1-weighted sequence of MR imaging from birth (full-term newborn) to 2 years of normal myelination (see memory card 3)
.

 

Magnetic resonance imaging is currently the best method for non-invasive evaluation of brain myelin development in children
.
The process of myelin formation in children is more complicated, and it is necessary to understand myelin formation and its MRI imaging manifestations
.
In addition, the normal progress of the development of the corpus callosum and the recognition of the normal terminal area of ​​myelination, remembering and storing memory cards are essential for understanding the development of the brain myelin in children
.

 

Literature source: Branson, HM; Normal myelination: a practical pictorial review.
[J].
Neuroimaging Clin N Am.
2013,23(2):183-95.

Source: Branson, HM; Normal myelination: a practical pictorial review.
[J].
Neuroimaging Clin N Am.
2013,23(2):183-95.
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