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Magnetic Resonance Imaging
of the Pediatric Spine
A. Jay Khanna, MD, Bruce A. Wasserman, MD,
and Paul D. Sponseller, MD
Abstract
Magnetic resonance is an excellent
modality for imaging pathologic
processes in the pediatric spine. It
allows high-resolution views of not
only osseous structures (including
the vertebral body, spinal canal, and
posterior elements) but also soft-tis-
sue structures (including the spinal
cord, intervertebral disk, and nerve
roots). Magnetic resonance imaging
(MRI) can show these structures in
various planes using different pulse
sequences that allow optimal char-
acterization of the tissues in and
around the pediatric spine. Indica-
tions for MRI in children (<18 years)
are gradually expanding as technol-
ogy improves. Properly interpreting
MRI scans in these age groups de-
pends on understanding the MRI
appearance of the normal pediatric
spine anatomy at various stages of
development. For entities such as
spinal dysraphism, left thoracic
curves, and juvenile scoliosis, spe-
cific recommendations can help cli-

nicians use MRI effectively.
MRI Techniques
The major factors that influence the
MRI appearance of various tissues are
the density of protons in the tissue,
the chemical environment of the pro-
tons, and the magnetic field strength
of the scanner. Unlike computed to-
mography (CT), which produces im-
ages based on the density of various
tissues, MRI produces images based
on free water content and on other
magnetic properties of water, yield-
ing superior soft-tissue contrast.
Various sequences are produced by
manipulating the strength of the ra-
diofrequency (RF) pulses, the inter-
val between the pulses, the repetition
time (TR), and the echo time (TE), that
is, the time between applying the RF
pulse and measuring the signal emit-
ted by the patient. By manipulating
these variables, the images can be
weighted to emphasize the T1, T2,
gradient-recalled echo, or proton den-
sity characteristics of a tissue. T1-
weighted images allow evaluation of
anatomic detail, including that of os-
seous structures, disk, and soft tissues.
T2-weighted images are used primar-

ily to evaluate the spinal cord and to
enhance lesion conspicuity.Agradient-
recalled echo sequence typically is used
when thin axial images are needed,
such as for evaluating foraminal nar-
rowing in the cervical spine, because
its three-dimensional acquisition al-
lows for very thin sections.
Standard pulse sequences for spi-
nal imaging include spin echo T1-
weighted images and fast spin echo
(FSE) T2-weighted images. The FSE
technique allows acquisition of scans
without prolonged imaging times. Be-
cause cerebrospinal fluid (CSF) is bright
on T2-weighted images and the spi-
nal cord retains its intermediate sig-
nal, the images maximize the contrast
between CSF and neural tissue, allow-
ing optimal delineation of the spinal
cord and nerve roots. T2-weighted im-
ages are very sensitive to pathologic
changes in tissue, including any pro-
Dr. Khanna is Chief Resident, Departmentof Or-
thopaedic Surgery, The Johns Hopkins Hospital,
Baltimore, MD. Dr. Wasserman is Assistant Pro-
fessor, Department of Radiology, The Johns Hop-
kins Hospital. Dr. Sponseller is Professor and Vice
Chairman, Department of Orthopaedic Surgery,
The Johns Hopkins Hospital.

Reprint requests: Dr. Sponseller, c/o Elaine P.
Henze, Room A672, 4940 Eastern Avenue, Bal-
timore, MD 21224-2780.
Copyright 2003 by the American Academy of
Orthopaedic Surgeons.
Magnetic resonance is an excellent modality for imaging the pediatric spine. Its suc-
cessful use requires understanding both the basic physics and the sedation protocols
necessary for acquiring high-resolution images. Interpreting the images accurately
depends on appreciating the differences between the normal anatomy of the pedi-
atric and the adult spine. Evaluating the images requires familiarity with the dif-
ferential diagnosis of pediatric spine disease, including the most common processes
(infections, neoplasms, and trauma) as well as spinal dysraphism. Despite the ac-
knowledged usefulness of magnetic resonance imaging of the pediatric spine, con-
troversies remain related to its safety in this age group and its limitations in di-
agnosing and evaluating scoliosis and tethered cord syndrome.
J Am Acad Orthop Surg 2003;11:248-259
248 Journal of the American Academy of Orthopaedic Surgeons
cesses in which cells and the extra-
cellular matrix have an increase in wa-
ter content. This pathologic change is
usually shown as an increase in sig-
nal intensity on T2-weighted images.
The signal from fat may be sup-
pressed by a variety of techniques, in-
cluding chemical saturation of its sig-
nal or application of an inversion
pulse, and imaging at a short time of
inversion (TI) when there is no fat sig-
nal present (short TI recovery [STIR]).
Chemical suppression typically is

used in sequences that result in high
fat signal, such as FSE T2-weighted
images or postcontrast T1-weighted
images. Fat suppression is of little val-
ue for noncontrast T1-weighted im-
ages because the signal from most
pathologic lesions, whether inflam-
matory,neoplastic, or infectious,isof-
ten low and better visualized because
of contrast against the adjacent bright
fat signal. Fat suppression on post-
contrast T1-weighted images of the
vertebral body is useful in adults who
have fatty transformation of marrow.
Fat-suppressed images may be par-
ticularly useful for evaluating liga-
mentous injuries or lesions involving
the paraspinal tissues. The usefulness
of STIR imaging is more limited be-
cause the imaging parameters are re-
stricted and cannot be optimized to
maximize contrast between adjacent
tissues of interest.
Gradient-recalled echo images ap-
pear to be T2-weighted because CSF
is relatively bright; however, paren-
chymal lesions typically are more con-
spicuous on FSE T2-weighted images.
The gradient-recalled echo sequence
is sensitive to local inhomogeneities

of the magnetic field, and signal loss
is exaggerated in the presence of such
inhomogeneities. Field inhomogene-
ities may be caused by metallic im-
plants (eg, pedicle screws or paraspi-
nal rods), differences in the magnetic
susceptibilities of adjacent tissues (eg,
air-tissue interfaces), and paramagnetic
substances (eg, gadolinium). Blood-
breakdown products cause local field
distortions resultinginsignalloss,mak-
ing this technique very sensitive for
the detection of blood.
Open MRI systems are being used
more frequently, especially for chil-
dren. These systems have notably
lower field strengths than do closed
systems and therefore usually pro-
duce studies of inferior overall qual-
ity, especially of the spine. However,
open MRI systems allow easier access
to the sedated or otherwise compro-
mised patient. Youngpatients and pa-
tients with claustrophobia have ac-
cess to parents and the environment,
making the procedure less intimidat-
ing. However, whenever possible,
spinal MRI should be done using
closed, 1.5-T systems.
Pediatric Sedation

Protocols
Sedation is often required for success-
ful MRI in young children. Many
studies have evaluated specific seda-
tion protocols.
1,2
The American Acad-
emy of Pediatrics (AAP) has pub-
lished guidelines for the elective
sedation of pediatric patients,
3,4
but
compliance with these guidelines is
not mandatory. The AAP has stated
that careful medical screening and pa-
tient selection by knowledgeable
medical personnel are needed to ex-
clude patients at high risk of life-
threatening hypoxia.
4
Also, monitor-
ing usingAAPguidelines is necessary
for the early detection and manage-
ment of life-threatening hypoxia.
3
The
AAP recommends that before an ex-
amination in which sedation is to be
used, children from newborn to age
3 years take nothing by mouth for 4

hours and those aged 3 to 6 years take
nothing by mouth for 6 hours.
4
Pediatric sedation practices vary,
but a few agents are common to most
protocols. Oral chloral hydrate is of-
ten recommended for children young-
er than 18 months. However, its use
is controversial because of its variable
absorption, paradoxical effects, and
nonstandardized dosing. Older chil-
dren usually receive intravenous pen-
tobarbital with or without fentanyl.
Although studies have reported
successful administration of sedatives
by trained nurses,
1,2
an anesthesiol-
ogist’s expertise can be beneficial for
patients with substantial comorbidi-
ties, including cardiopulmonary dis-
ease, skeletal dysplasias, neuromus-
cular disease, and abnormal airway
anatomy. Because of the potential risks
of anesthesia and sedation in children,
there is a trend toward referring those
who require sedation to hospitals with
pediatric anesthesiologists.
An important consideration after
sedation for pediatric MRI is the need

for strict adherence to established dis-
charge criteria, including return to
baseline vital signs, level of con-
sciousness close to baseline, and abil-
ity to maintain a patent airway.
5
Be-
cause of the inherent risks of sedation,
alternative techniques have been de-
vised, including sleep deprivation
and rapid, segmental scanning. The
latter permits acquisition of high-
quality images without the use of se-
dation.
Normal MRI Anatomy
Appreciating normal MRI anatomy
(Fig. 1) is essential for understanding
and predicting the MRI appearance
of pathologic processes.
6
Adolescents and Adults
The lumbar spine is more fre-
quently imaged than the cervical and
thoracic area in both children and
adults. In adolescents and adults, the
lumbar spinal canal appears round
proximally and triangular distally.
The lumbar facet joints, best visual-
ized in the axial plane, are covered
with 2 to 4 mm of hyaline cartilage.

This cartilage can be well visualized
with FSE and gradient-recalled echo
pulse sequences. The epidural space
and ligaments also should be evalu-
ated carefully. Epidural fat is seen as
high signal intensity on T1-weighted
A. Jay Khanna, MD, et al
Vol 11, No 4, July/August 2003 249
images; the ligamentum flavum
shows minimally higher T1-weighted
signal compared with the other lig-
aments. The conus medullaris is usu-
ally located at the L1-L2 level. The tra-
versing nerve roots pass distally from
the conus medullaris and extend an-
teriorly and laterally, exiting lateral-
ly underneath the pedicle and extend-
ing into the neural foramen. The
intervertebral disk, consisting of the
cartilaginous end plates, anulus fibro-
sus, and nucleus pulposus, normally
shows increased T2-weighted signal
in its central portion. CSF, well im-
aged as low T1-weighted and high
T2-weighted signal, often can be used
to determine the type of pulse se-
Figure 1 A, Sagittal T1-weighted MRI scan of a normal lum-
bar spine in a 2-year-old boy shows the rectangular shape of
the vertebral bodies. The conus medullaris is seen at the L1-L2
level (arrow). B, T2-weighted image shows the long, thin ap-

pearance ofthe intervertebral disk. C,Sagittal T1-weighted scan
of a normal lumbar spine in a 10-year-old girl. D, T2-weighted
scan. Lordosis is normal. The posterior elements are well
formed, with a resultant decrease in the canal diameter. E, Sag-
ittal T1-weighted scan of a normal lumbar spine in a 16-year-
old girl shows dark CSF (thin arrow), the conus medullaris at
the L1-L2 level (open arrow), and the basivertebral channel
(arrowhead). Note the normal rectangular appearance of the
vertebral bodies and the lumbar lordosis compared with the
10-year-old girl. F, Sagittal T2-weighted scan shows bright CSF
(thin arrow) and a bright nucleus pulposus (arrowhead).
Magnetic Resonance Imaging of the Pediatric Spine
250 Journal of the American Academy of Orthopaedic Surgeons
quence that is being used. CSF pul-
sations often create artifacts that de-
grade the image in the lumbar spine;
these artifacts must not be mistaken
for a pathologic process.
The cervical spine shows a mild
lordosis on sagittal images. On axial
images, the spinal canal is triangular,
with the base located anteriorly. A
dark band at the base of the dens is
a normal variant that is a remnant of
the subdental synchondrosis and
should not be mistaken for a fracture.
In adults, the facet joints are small and
triangular, whereas in children they
are large and flat. The spinal cord is
elliptical in cross section in the cer-

vical spine. There isadifference in sig-
nal between the normal gray and
white matter of the spinal cord. This
signal heterogeneity should not be
mistaken for intramedullary pathol-
ogy. The intervertebral disks are sim-
ilar in appearance to, but smaller
than, those seen at the thoracic and
lumbar levels. An important anatom-
ic feature of the cervical spine is the
prominent epidural venous plexus,
which is not present in the thoracic
or lumbar spine.
The thoracic vertebral bodies are
relatively constant in size, and the spi-
nal canal is almost round. Abundant
epidural fat is present posteriorly, but
there is less anteriorlythaninthelum-
bosacral region. The cord is more
round than in the cervical or lumbar
regions, and the cord segment lies
two to three levels above the corre-
sponding vertebral body. The inter-
vertebral disks are thinner than the
disks in the lumbar spine. The ap-
pearance of the CSF is more variable
in the thoracic spine than in the lum-
bar region because of more prominent
CSF pulsations, but on T1-weighted
images, it is commonly seen as a re-

gion of low signal dorsal to the spi-
nal cord. This artifact is often most se-
vere at the apex of curves, including
the thoracic kyphosis. Certain tech-
niques can minimize this artifact, in-
cluding gating to the pulse or cardi-
ac cycle.
Children
Differences Between the Pediatric and
the Adult Spine
The MRI appearance of the grow-
ing spine is complex. Substantial
changes occur in the vertebral ossi-
fication centers and the intervertebral
disks, changing the overall appear-
ance of the spine markedly, especial-
ly between infancy and age 2 years.
7
In general, the vertebral ossification
centers are incompletely ossified ear-
ly in childhood, and the disks are
thicker and have a higher water con-
tent than those in adults. The spinal
canal and neural foramina are larger,
and there is less curvature. In addi-
tion, the overall signal intensity of the
vertebral bodies is lower than that of
the adult spine on T1-weighted im-
ages because of the abundance of red
(hematopoietic) marrow relative to

yellow (fat) marrow in the pediatric,
adolescent, and young adult spine.
Full-Term Infant
In the newborn, the overall size of
the vertebral body is small relative to
the spinal canal, and the spinal cord
ends at approximately the L2 level.
The lumbar spine does not exhibit the
usual lordosis and is straight. The ver-
tebral bodies show a markedly low
signal intensity on T1-weighted im-
ages, with a thin, central, hyperin-
tense band that likely represents the
basivertebral plexus. The spongy
bone of the ossification center is el-
lipsoid rather than rectangular and
often mistaken for disk. The interver-
tebral disk is relatively narrow and
often contains a thin, bright central
band on T2-weighted images that
represents the notochordal rem-
nants.
6,7
Age 3 Months
At age 3 months, the osseous com-
ponent of the vertebral body has in-
creased and the amount of hyaline
cartilage has decreased, giving the
vertebral bodies a rectangularappear-
ance. The ossification centers begin to

gain in signal intensity, starting at the
end plates and progressing centrally.
The neural foramina have not sub-
stantially changed at this age, remain-
ing relatively large and ovoid.
6,7
Age 2 Years
At age 2 years, the spine has be-
gun to show its normal sagittal align-
ment, most likely because of weight
bearing (Fig. 1,Aand B). The ossified
portion of the vertebral body increas-
es substantially and begins to assume
its adult appearance, with near-
complete ossification of the pedicles
and the articular processes. The disk
space and nucleus pulposus become
longer and thinner. The cartilaginous
end plate has decreased in size and
is often difficult to identify. The neu-
ral foramen also begins to take its
adult appearance as its inferior por-
tion narrows.
7
Age 10 Years
At age 10 years, sagittal alignment
resembles that of an adult (Fig. 1, C
and D). Ossification of the vertebral
bodies and posterior elements is near-
ly complete, with a resultant decrease

in the spinal canal diameter. The ver-
tebral bodies also develop concave
superior and inferior contours. The
nucleus pulposus becomes smaller at
this age and spans approximately half
the disk space in the sagittal plane.
The neural foramina continue to nar-
row inferiorly.
6
The Conus Medullaris
In early fetal life, the spinal cord
extends to the inferior aspect of the
bony spinal column.
6
Because the ver-
tebral bodies grow more rapidly lon-
gitudinally than the spinal cord does,
by birth the conus medullaris is re-
positioned in the upper lumbar spine.
It is important to note the location of
the conus medullaris on every pedi-
atric spine MRI study (Fig. 1, A and
E).Aconus medullaris level below the
L2-3 interspace in children older than
5 years is abnormal and indicates pos-
sible tethering.
8,9
Saifuddin et al
10
re-

A. Jay Khanna, MD, et al
Vol 11, No 4, July/August 2003 251
viewed the MRI findings in 504 nor-
mal adult spines and found that the
average position of the conus med-
ullaris was the lower third of L1
(range, middle third of T12 to upper
third of L3).
Pathologic Processes in the
Pediatric Spine
Infection
Infectious processes involving the
pediatric spine include osteomyelitis,
diskitis, and epidural and paraspinal
abscess.
11-13
In general, the MRI sig-
nal characteristics of infection include
a region of low T1 and high T2 sig-
nal intensity in bone and soft tissue.
In identifying vertebral osteomy-
elitis, MRI is more sensitive than con-
ventional radiographs or CT and
more specific than nuclear scintigra-
phy.
14,15
Marrow edema can be detect-
ed on precontrast, fat-suppressed,
FSE T2-weighted images. Postgado-
linium enhancement of the disk and

adjacent vertebral bodies on postcon-
trast, fat-suppressed, T1-weighted
images helps confirm the diagnosis.
The specificity of MRI for infection is
higher in childrenthanadultsbecause
one of the primary confounders, de-
generative arthritis, is not part of the
differential diagnosis. Differentiating
osteomyelitis from neoplastic disease
is a common dilemma; generally, in-
fectious processes are more likely to
cross and destroy intervertebral disks
than are neoplastic conditions.
Diskitis is seen as a disruption of
the normally well-defined disk-
vertebral borders on T1-weighted im-
ages and as an increase in signal of
the disk on T2-weighted images.
12
On
T2-weighted images, diskitis may
obliterate the normally seen horizon-
tal cleft within the intervertebral disk.
The abnormal signal seen in infec-
tious diskitis is associated classically
with surrounding soft-tissue inflam-
mation and reactive end-plate chang-
es. Primary diskitis is more likely to
develop in children than adults be-
cause of the greater blood supply to

the disk. Secondary diskitis after dis-
kography or surgery is more likely to
develop in adults.
Epidural abscessesare rare,butwhen
they do develop, it is usually after sur-
gery or vertebral osteomyelitis. Epi-
dural abscesses are diagnosed based
on the MRI findings of a collection in
the epidural space and the appropri-
ate clinical setting.
11
Gadolinium-
enhanced T1-weighted images often
show a peripheral rim of enhancement
that represents the abscess wall.
Paraspinal abscesses occur adja-
cent to the spinal column, most com-
monly in the paraspinal musculature.
They may be secondary to a primary
infection in the spine or may arise
spontaneously in the paraspinal mus-
culature. These abscesses may be seen
as retropharyngeal abscesses in the
cervical spine, paraspinous or retro-
mediastinal abscesses in the thoracic
spine, or psoas abscesses in the lum-
bar spine. The MRI characteristics of
paraspinal abscesses include a well-
defined wall and peripheral enhance-
ment on postgadolinium, T1-

weighted images.
Trauma
MRI can be used to evaluate the
pediatric spinal trauma victim who
has an abnormal neurologic exami-
nation or is unresponsive. The patient
is first evaluated with conventional
radiographs, which may be normal,
even in a child with a neural deficit.
Although CT allows for better eval-
uation of osseous detail and displaced
fractures, MRI provides improved
evaluation of nondisplaced fractures
because of its ability to detect
marrow-signal abnormalities.
Spinal cord injury without radio-
graphic abnormality (SCIWORA) is
a well-defined entity seen in the pe-
diatric age group.
16,17
The character-
istic hypermobility and ligamentous
laxity of the pediatric bony cervical
and thoracic spine predispose children
to this type of injury.
16
The elasticity
of the bony pediatric spine and the
relatively large size of the head allow
the musculoskeletal structures to de-

form beyond physiologic limits, which
results in cord trauma followed by
spontaneous reduction of the spine.
16
As with other types of spinal cord
injuries, the most important predic-
tor of outcome is the severity of neu-
rologic injury. A patient with a com-
plete neurologicdeficitafterSCIWORA
has a poor prognosis for recovery of
neurologic function. The role of MRI
in SCIWORA syndrome is to define
the location and the degree of neural
injury, rule out occult fractures and
subluxation that may require surgi-
cal intervention, and evaluate for the
presence of ligamentous injury. T2-
weighted images typically show in-
creased signal in the cord, vertebral
body, or ligaments. The increased T2
signal in the cord is compatible with
edema and can range from a partial,
reversible contusion to complete
transection of the cord.
Two other traumatic entities can oc-
cur in children, usually as the result
of participation in sports. The first is
acute disk herniation. This is often a
fracture with a hingelike displacement
of fibrocartilage and slipping of the

entire disk with vertebral end-plate
fracture rather than extrusion of a disk
fragment from the nucleus, as is seen
in adults.
18
Such avulsion fractures are
often occult on conventional radio-
graphs and are better detected with
CT and MRI.
18
Axial MRI scans dem-
onstrate the fracture fragment as an
area of low signal intensity protrud-
ing into the spinal canal, and sagittal
images demonstrate a low signal in-
tensity region in the shape of a Y or
7 on all pulse sequences.
18
The second entity is a spondylo-
lysis as a cause of back pain in young
athletes. MRI, however, is not the op-
timal method for evaluating spondy-
lolysis. CT offers increased spatial res-
olution and the ability to accurately
define the osseous defect, whereas ra-
dionuclide imaging can demonstrate
increased radiotracer activity in the
region of the defect.
Magnetic Resonance Imaging of the Pediatric Spine
252 Journal of the American Academy of Orthopaedic Surgeons

Neoplasms
MRI is the modality of choice for
evaluating neoplasms in and around
the pediatric spine.
19
An effective and
commonly used approach is to clas-
sify the lesion as extradural, intra-
dural-extramedullary (Fig. 2), or in-
tradural-intramedullary (Fig. 3). With
this anatomic classification system,
the primary role of the MRI exami-
nation is to define the location of the
suspected neoplasm, which is best
achieved with axial and sagittal T1-
and T2-weighted images. Once the
lesion has been classified, the T2-
weighted images can be used to char-
acterize the lesion further. Specifical-
ly, the degree of surrounding edema
and tissue infiltration and the pres-
ence or absence of a cystic component
can be determined. Next, postgado-
linium enhancement images should
be compared with unenhanced T1-
weighted images. The final step in ob-
taining a diagnosis is to correlate the
imaging findings with the patient’s
age and other criteria to narrow the
differential diagnosis.

Spinal Dysraphism
Spinal dysraphism is a general term
used to describe a wide range of
anomalies resulting from incomplete
fusion of the midline mesenchyma,
bone, and neural elements. The os-
seous abnormalities consist of defects
within the neural arch with partial or
complete absence of the spinous pro-
cesses, laminae, or other components
of the posterior elements. MRI has
been shown to be the best modality
for evaluating spinal dysraphism.
20,21
A classification system has been
proposed for evaluating a patient
with a suspected spinal dysraphism
(Table 1).
21
The differential diagnosis
can be narrowed to one of three types:
spinal dysraphism with a back mass
either covered or not covered with
skin, or with no back mass. The final
diagnosis then can be made based on
the lesion’s MRI characteristics.
Myelomeningocele is the most
common form of spinal dysraphism
(Fig. 4). It usually presents in the lum-
bosacral region (although it can be

seen at higher levels) as a back mass
not covered with skin. The mass may
or may not be covered by lepto-
meninges containing a variable
amount of neural tissue. The sac her-
niates through a defect in the poste-
rior elements of the spine. The spinal
cord usually contains a dorsal cleft,
Figure 2 A schwannoma in an 8-year-old boy. A, Sagittal T1-weighted MRI scan shows an
intradural-extramedullary mass impressing on the anterior cervical cord at the C5 level (ar-
row). B, Axial T2-weighted image shows the lesion herniating through the right C5-C6 neu-
ral foramen (arrows).
Figure 3 An astrocytoma in a 6-year-old boy. A, Sagittal T1-weighted MRI scan shows an intradural-intramedullary lesion within the spi-
nal cord at the T3-T5 levels (arrow). B, Sagittal T2-weighted image shows the partially cystic nature of the lesion. C, Axial T2-weighted
image confirms that the lesion (arrow) is within the center of the spinal cord.
A. Jay Khanna, MD, et al
Vol 11, No 4, July/August 2003 253
is splayed open, and is often tethered
within the sac.
21
Progressive scolio-
sis is seen in 66% of patients with my-
elomeningocele, Arnold-Chiari type
II malformation in 90% to 99%, di-
astematomyelia in 30% to 40%, and
syringohydromyelia in 40% to
80%.
22
Scarring can occur at the sur-
gical site after sac closure, so it is im-

portant to monitor these patients for
signs and symptoms of tethered cord
syndrome.
Of the entities presenting with a
skin-covered back mass in the pres-
ence of spinal dysraphism, lipomen-
ingocele is the most common.
6,21
The
lipomeningocele consists of lipoma-
tous tissue that is continuous with the
subcutaneous tissue of the back and
also insinuates through the dysraph-
ic defect and dura and into the spi-
nal canal. The spinal cord often con-
tains a dorsal defect at the level of the
lipomatous tissue and may be teth-
ered at this level. The essential MRI
feature of this lesion is that the li-
pomatous tissue follows the signal
characteristics of subcutaneous fat on
all pulse sequences, including fat-
suppressed pulse sequences.
Occult spinal dysraphism pre-
sentswithouta backmass.Diastema-
tomyelia is characterized by a sagit-
tal splitting into two segments of the
spinal cord, conus medullaris, or
filum terminale, often in the thoracic
or lumbar spine. The dural tube and

arachnoid are undivided in approx-
imately half these patients; clinical
findings are rare, and surgery is not
indicated. In the remaining patients,
the dural tube and arachnoid are
completely or partially split at the
level of the spinal cord cleft, which
results in tethering of the cord and
subsequentclinicalsymptoms. Coro-
nal T1- and T2-weighted images
best define the sagittal split in the
cord; the findings should be con-
firmed on axial images.
Another entity often seen in pa-
tients with spinal dysraphism is sy-
ringohydromyelia, or a syrinx (Fig. 5).
Asyrinx is a longitudinal cavity with-
in the spinal cord that may or may
not communicate with the central ca-
nal. Attempts to explain the etiology
include developmental, traumatic, in-
flammatory, ischemic, and pressure-
related causes. Sagittal MRI scans
show a linear, low T1 and high T2 sig-
Table 1
Classification of Spinal Dysraphism
Category Types
Back mass not covered with skin Myelomeningocele
Myelocele
Back mass covered with skin Lipomyelomeningocele

Myelocystocele
Simple posterior meningocele
No back mass (occult) Diastematomyelia
Dorsal dermal sinus
Intradural lipoma
Tight filum terminale
Anterior sacral meningocele
Lateral thoracic meningocele
Hydromyelia
Split notochord syndrome
Caudal regression syndrome
(Adapted with permission from Byrd SE, Darling CF, McLone DG, Tomita T: MR im-
aging of the pediatric spine. Magn Reson Imaging Clin North Am 1996;4:797-833.)
Figure 4 A myelomeningocele in a 6-year-old girl. A, Sagittal T1-weighted MRI scan shows a low-back mass contiguous with the contents
of the spinal canal (arrows). B, T2-weighted image shows that the mass is filled with high-signal-intensity fluid, compatible with CSF (ar-
rows). C, Axial T1-weighted image confirms that the mass communicates with the spinal canal through a defect in the posterior elements
(arrows).
Magnetic Resonance Imaging of the Pediatric Spine
254 Journal of the American Academy of Orthopaedic Surgeons
nal intensity within the parenchyma
of the spinal cord.
Gibbs artifact, or truncation arti-
fact, can mimic a syrinx on sagittal
images (Fig. 6). Gibbs artifact is seen
on sagittal T1- and T2-weighted im-
ages as a linear region of altered sig-
nal intensity in the center of the spi-
nal cord. Thus, it is important to
evaluate serial axial T1- and T2-
weighted images to confirm findings.

Gibbs artifact results from not using
a sufficiently high spatial frequency
for sampling data. It can be corrected
by using a higher-resolution matrix.
Chiari Malformations
Chiari malformations are seen fre-
quently in patients with spinal dys-
raphism. Chiari type I malformations
consist of cerebellar tonsillar ectopia,
in which the cerebellar tonsils extend
below the level of the foramen mag-
num. The common measurement for
the degree of herniation of the ton-
sils below the foramen magnum is 5
mm. Mikulis et al
23
reported a vari-
Figure 5 A large syrinx involving the entire spine in a 2-year-old boy. A, Sagittal T1-weighted MRI scan shows the syrinx to be largest
at the level of the lower thoracic spine (arrows). Axial T1-weighted (B) and T2-weighted (C) images confirm that the syrinx is located within
the center of the spinal cord.
Figure 6 A 5-year-old girl had a history of
neck and arm pain. A, Sagittal T2-weighted
MRI scan shows a long linear region of high
signal intensity within the center of the cer-
vical spinal cord (arrow). This finding can
easily be mistaken for a syrinx. B, Sagittal
T1-weighted image also suggests low signal
intensity in the same region but fails to
show a syrinx, demonstrating normal cord
anatomy. C, Axial T2-weighted image also

demonstrates normal anatomy. These find-
ings are compatible with a Gibbs artifact.
A. Jay Khanna, MD, et al
Vol 11, No 4, July/August 2003 255
ation by age in the upper limit of nor-
mal: 6 mm in the first decade of life,
5 mm in the second and third de-
cades, and 3 mm by the ninth decade.
In Chiari I malformations, the brain-
stem is spared and the fourth ventri-
cle remains in its normal location.
Chiari I malformations are associat-
ed with syringohydromyelia, cranio-
vertebral junction anomalies, and
basilar invagination. Chiari II malfor-
mations are more advanced and con-
sist of downward displacement of the
brainstem and inferior cerebellum into
the cervical spinal canal, with a de-
crease in size of the posterior fossa.
Tethered Cord Syndrome
Tethered cord syndrome is seen in
a substantial number of patients with
spinal dysraphism, especially those
who have undergone surgical closure
of the defect.
24,25
During fetal life, the
spinal cord extends to the sacrococ-
cygeal level.Becauseofthe rapid growth

of the vertebral column after birth, the
cord ascends to the L1-L2 level in the
newborn. During the formation of a
spinal dysraphic defect such as my-
elomeningocele, the open neural el-
ements often attach to the peripheral
ectoderm, resulting in spinal cord teth-
ering. After surgical closure of the sac,
there is a tendency for the spinal cord
to become adherent at the repair site.
As the child grows, this adherence may
tether the cord and prevent cephalad
cord migration, with eventual symp-
toms. Thus, in patients with spinal dys-
raphic and related conditions, includ-
ing myelomeningoceles, myeloceles,
lipomeningoceles, and diastematomy-
elia, tethered cord should be ruled out
as the potential cause of any deteri-
oration in neurologic function.
MRI has been proposed as the ini-
tial, and possibly only, imaging study
for a patient with a suspected teth-
ered spinal cord.
9
Sagittal images
should be evaluated to determine the
level of the conus medullaris (Fig. 7).
A conus level below the L2-L3 inter-
space in children older than 5 years

is abnormal and an indication of pos-
sible tethering.
8,9
In addition, the teth-
ered cord is often displaced posteri-
orly in the spinal canal. Other findings
include lipoma or scar tissue within
the epidural space and increased thick-
ness of the filum terminale.
9
Although
MRI can determine whether a spinal
cord is anatomically tethered, these
findings should be correlated with the
patient’s symptoms and serial phys-
ical examinations before surgical re-
lease is considered.
Controversies in MRI of
the Pediatric Spine
MRI of the pediatric spine remains
controversial in several conditions, in-
cluding scoliosis and tethered cord
syndrome, as well as with spinal in-
strumentation. Safety is also a concern.
Scoliosis
The use of MRI imaging in scoli-
osis is primarily to detect intraspinal
abnormalities, which are more fre-
quently associated with uncommon
curve patterns such as left thoracic

curves, an abnormal neurologic ex-
amination, or young age at pre-
sentation.
26-30
Recently, Do et al
26
con-
cluded that MRI is not indicated
before spine arthrodesis in a patient
with an adolescent idiopathic scoli-
osis curve pattern and a normal phys-
ical and neurologic examination.
One area of particular controversy
is back pain in the presence of scolio-
sis. In a retrospective study of 2,442
Figure 7 A14-year-old boy had ahistory of lipomeningocele.After surgical resection, bowel
and bladder dysfunction and new lower-extremity paresthesias developed. A, Sagittal T2-
weighted image shows the conus medullaris extending to approximately the L4 level and
the filum terminale extending to the S1 level (arrow), compatible with tethered cord syn-
drome. B, Axial T2-weighted image at the L4 level shows the cord located posteriorly within
the thecal sac (arrow). C, Axial T2-weighted image at the L5 level shows the placode (thin
arrow) with a right-side nerve root (thick arrow) coursing anteriorly and laterally.
Magnetic Resonance Imaging of the Pediatric Spine
256 Journal of the American Academy of Orthopaedic Surgeons
patients, Ramirez et al
31
found that a
left thoracic curve or abnormal result
on neurologic examination best pre-
dicted an underlying pathologic con-

dition. They found a significant asso-
ciation between back painandageolder
than 15 years (P < 0.001), skeletal ma-
turity (P < 0.001), postmenarcheal sta-
tus (P < 0.001), and history of injury
(P<0.018).Theauthors concluded that
it is unnecessary to perform extensive
diagnostic studies on every patientwith
scoliosis and back pain. MRI should
be reserved for patients with infan-
tile or juvenile scoliosis, left thoracic
curves, or abnormal neurologic find-
ings. Because coronal views are espe-
cially useful in evaluating patients with
scoliosis, they should be a part of the
routine imaging protocol.
Tethered Cord Syndrome
The rate of MRI in tethered cord
syndrome remains controversial.
When MRI demonstrates a tethered
cord, a choice between surgical and
nonsurgical treatment must be made.
Although anatomic tethering of the
cord is detected easily on MRI, indi-
cations for surgery depend on the
clinical history and results of serial
physical examinations.
Imaging in the Presence of
Implants
MRI of the spine in the presence

of instrumentation is generally safe
but is limited by the image artifacts
the implants produce. The pulse se-
quence used for imaging titanium
produces less degradation from arti-
fact because it is less ferromagnetic
than stainless steel (Fig. 8).
32,33
Thus,
titanium may be the better choice of
implant in a patient who may require
follow-up with MRI. However, with
appropriate imaging techniques, clin-
ically useful information can be ob-
tained safely in the presence of both
types of implants.
34
Specialized pulse
sequences such as the metal artifact
reduction sequence (MARS) can help
reduce the degree of tissue-obscuring
artifact produced by spinal hardware
and improve image quality compared
with conventional T1-weighted spin-
echo pulse sequences.
35
MRI Safety
MRI may be contraindicated in pa-
tients with ferromagnetic implants,
materials, or devices because of the

risk of implant dislodgement, heat-
ing, and induction of current.
36
Shel-
lock et al
36
reviewed and compiled the
results of more than 80 studies and
described the ferromagnetic qualities
of 338 objects, including 30 ortho-
paedic implants, materials, and devic-
es. They found that most orthopaedic
implants are made from nonferro-
magnetic materials and therefore are
safe for MRI procedures. Another
concern is that of safety within the
MRI suite. Areas surrounding and
Figure 8 A 6-year-old boy had a
history of high-grade astrocytoma.
A, Anteroposterior radiograph6 weeks
after resection, multilevellaminectomy,
and posterior spinalarthrodesis from
T4 to L3 with titaniumpedicle screws,
hooks, and rods. B, Midline sagittal
postgadolinium T1-weightedMRIscan
allows visualization of thecanal con-
tents with minimal artifact from the
pedicle screws (arrows). C, Parasag-
ittal postgadolinium T1-weighted im-
age shows a rod (thick arrow) and

pedicle screw (thin arrow). Neither
obscures theMRI scan. D,Axial post-
gadolinium T1-weighted image also
shows thepedicle screws (arrows) and
a patent spinal canal.
A. Jay Khanna, MD, et al
Vol 11, No 4, July/August 2003 257
within the suite should be carefully
monitored for the presence of ferro-
magnetic equipment that may act as
a projectile and injure the patient or
hospital personnel. A recent report
described a series of projectile cylin-
der accidents when ferromagnetic ni-
trous oxide or oxygen tanks were in
the MRI suite.
37
Other equipment (eg,
intravenous pumps, hospital beds,
handheld instruments) also should be
compatible with MRI.
Summary
MRI is an excellent modality for ad-
vanced imaging of the pediatric
spine. A basic understanding of the
normal MRI appearance of the spine
at various ages, the signal character-
istics of various pathologic changes,
and the differential diagnosis of spi-
nal pathology can help the clinician

correlate the history and physical
examination with MRI findings to
establish the most likely diagnosis.
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