Tracing the Normal Myelination Pattern on Neonatal MRI ... · poster presents a systematic approach...
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Tracing the Normal Myelination Pattern on Neonatal MRI Brain Imaging; from Birth to Two Years . Dr Sinéad Culleton, Dr Clare Roche, Dr Declan Sheppard Department of Radiology, Galway University Hospital, Ireland Purpose After birth the immature paediatric brain undergoes further maturation and most importantly maturation of the myelinated structures essential for propagation of impulses which will allow normal development. This occurs in a step wise predictable fashion. Understanding the normal progression of myelination can avoid misinterpretation of normal changes as pathology and also identify pathology affecting the normal maturation process. Disruption in the predicted normal myelination pattern is important to recognise as many referrals in this age are for investigation of developmental delay or developmental abnormality. This poster presents a systematic approach to recognising the expected myelinated structures at a number of ages from birth to two years. Discussion Myelination begins in utero. Maturation is predominantly complete by 2 years of age but does continue into adulthood. The expected progression is craniocaudally from deep to superficial, from posterior to anterior, with sensory proceeding motor. The major changes occurring in chemical composition account for the changes seen on T1 and T2 imaging 1, 2 . The higher water content mean that the T1 and T2 relaxation times are longer than those of an adult brain. These relaxation times shorten with maturation. From birth to approximately 4-6months the normal myelination pattern is the reverse of the adult and white matter is of lower signal than grey matter on T1 (Figure 1) and of higher signal on T2( Figure 2) 1, 3, 4 . Figure 1: T1-weighted axial image from an MRI brain of an 11 day old neonate. The grey matter is of lower signal on T1 than the surrounding grey matter. Figure 2: T2-weighted axial image from an MRI brain of an 11 day old neonate. The white matter here is seen as hyperintense to the surrounding grey matter. T1 and T2 myelination milestones term birth: brainstem, cerebellum, posterior limb of the internal capsule, optic tract, perirolandic region 2-3 months: anterior limb of the internal capsule 3-4 months: splenium of the corpus callosum 4-6 months: genu of the corpus callosum References 1. Ballesteros M, Hansen P, Soila K. MR Imaging of the developing human bran, part 2 postnatal development. Radiographics 1993; 13:611-622. 2. Yakovlev Pl, Lecours AR. The myelogenetic cycle of regional maturation of the brain. In: Minkowski A, ed. Regional development of the brain in early life. Philadelphia, Pa:Davis 1967; 3-69. 3. Holland BA, Haas DK, Norman D, Brant-Zawadzki M, Newton TH. MRI of normal brain maturation. AJNR 1986; 7:201-208. 4. Baierl P, Forster Ch, Fendel H, Naegele M, Fink U, Kenn W. Magnetic resonance imaging of normal and pathological white matter maturation. Paediatr Radio 1988; 18:183-189. Knaap MS, Valk J, Barkhof F. Magnetic resonance of myelination and myelin disorders. Springer Verlag. (2005) T2- weighted images at 6 months showing myelination of the splenium of the corpus callosum. Image 2 at 10 months and image 3 at 2 years show progressive myelination in the internal capsule, corpus callosum, forceps minor and forceps major. T1-weighted axial images of an 11 day old neonate showing myelination in the peri-rolandic region, the posterior limb of the internal capsule and brainstem. T1 is the most sensitive for children < 1 year 5 T2 is the most sensitive sequence for children >1 year It is important to understand the normal progression of myelination to identify myelination abnormalities. At two years of age the myelination pattern resembles that of an adult. However, myelination continues in some areas such as subcortical white matter 1 .
Transcript of Tracing the Normal Myelination Pattern on Neonatal MRI ... · poster presents a systematic approach...
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.
