TracingtheNormalM

yelin

ationPatternon

Neo

natalM

RIBrainIm

aging;from

BirthtoTwoYears.

DrSiné

adCu

lleton,DrC

lareRoche

,DrD

eclanShep

pard

Departmen

tofR

adiology,G

alwayUniversity

Hospital,Ire

land

Purpose

Afterbirththeim

maturepaed

iatricbrainun

dergoe

sfurthe

rmaturationandmostimpo

rtantly

maturationof

the

myelinated

structures

essentialfor

prop

agationof

impu

lseswhich

willallowno

rmalde

velopm

ent.Thisoccursina

step

wise

pred

ictablefashion.

Und

erstanding

theno

rmalprog

ressionof

myelinationcanavoidmisinterpretation

ofno

rmalchangesas

pathologyandalso

iden

tifypathologyaffectingtheno

rmalmaturationprocess.Disrup

tion

inthepred

ictedno

rmal

myelinationpatte

rnis

impo

rtantto

recognise

asmanyreferralsin

this

agearefor

investigationof

developm

entald

elay

orde

velopm

entalabn

ormality.T

hispo

ster

presen

tsasystem

aticapproach

torecognising

theexpe

cted

myelinated

structures

atanu

mbe

rofagesfrom

birthto

twoyears.

Discussion

Myelinationbe

gins

inutero.

Maturationis

pred

ominantly

completeby

2yearsof

agebu

tdo

escontinue

into

adulthoo

d.Theexpe

cted

progressioniscraniocaud

allyfro

mde

epto

superficial,fro

mpo

steriorto

anterio

r,with

sensoryproceeding

motor.The

major

changeso

ccurrin

ginchem

icalcompo

sitionaccoun

tfor

thechangess

eenon

T1andT2

imaging

1,2 .Thehigher

water

conten

tmeanthat

theT1

andT2

relaxatio

ntim

esarelonger

than

thoseof

anadultbrain.

Theserelaxatio

ntim

esshortenwith

maturation.

From

birthto

approxim

ately4-6m

onthsthe

norm

almyelinationpatte

rnisthereverseof

theadulta

ndwhite

matterisof

lower

signalthangrey

mattero

nT1

(Figure1)

andof

higher

signalonT2(Figure2)

1,3,4 .

Figure

1:T1-w

eighted

axialim

agefro

man

MRI

brain

ofan

11day

old

neon

ate.

Thegrey

matter

isof

lower

signalon

T1than

thesurrou

ndinggrey

matter.

Figure

2:T2-w

eightedaxialimage

from

anMRI

brainof

an11

dayold

neon

ate.

Thewhite

matterhe

reis

seen

ashype

rintense

tothe

surrou

ndinggrey

matter.

T1and

T2myelin

ationmileston

esterm

birth:

brainstem,cereb

ellum,posterio

rlim

bofth

einternalcapsule,optictract,pe

rirolandicregion

2-3mon

ths:anterio

rlim

bofth

einternalcapsule

3-4mon

ths:splenium

ofthe

corpu

scallosum

4-6mon

ths:genu

ofthe

corpu

scallosum

References

1.Ballesteros

M,H

ansenP,Soila

K.MRIm

agingof

thede

veloping

human

bran,part2

postnataldevelop

men

t.Radiograph

ics1

993;

13:611-622.

2.Yakovlev

Pl,Lecou

rsAR

.The

myelogenetic

cycleof

region

almaturationof

thebrain.

In:M

inkowskiA

,ed.

Region

alde

velopm

ento

fthe

brainin

early

life.

Philade

lphia,Pa:Davis

1967;3-69.

3.Ho

lland

BA,H

aasDK

,Norman

D,Brant-Z

awadzkiM,N

ewtonTH

.MRIof

norm

albrainmaturation.AJNR

1986;7:201-208.

4.BaierlP,ForsterC

h,Fend

elH,

NaegeleM,FinkU,

Kenn

W.M

agne

ticresonanceim

agingof

norm

alandpathologicalwhite

matterm

aturation.Paed

iatrRadio1988;18:183-189.

KnaapMS,ValkJ,Barkho

fF.M

agne

ticresonanceof

myelin

ationandmyelin

disorders.Sprin

gerV

erlag.(2005)

T2-w

eightedim

agesat6

mon

thss

howingmyelinationofth

esplenium

ofthe

corpu

scallosum.Image2at

10m

onthsandim

age3at2yearssh

owprogressiv

emyelinationinth

einternalcapsule,corpu

scallosum,

forcep

sminorand

forcep

smajor.

T1-w

eightedaxialimagesofan11dayoldneo

natesh

owingmyelinationinth

epe

ri-roland

icregion

,the

posteriorlim

bofth

einternalcapsuleand

brainstem.

T1isthemostsen

sitiv

eforchildren<1year

5

T2isthemostsen

sitiv

esequ

ence

forchildren>1

year

Itisim

portanttoun

derstand

theno

rmalprogressionof

myelinationto

iden

tifymyelinationabno

rmalities.

Attw

oyearsof

agethemyelinationpa

ttern

resembles

that

ofan

adult.Ho

wever,m

yelinationcontinue

sin

someareass

uchas

subcorticalwhite

matter1.