SPINAL CORD TUMORS MRI AND CT FEATURES. Extraxial and intraaxial

1. MRI : SPINAL CORD TUMORS

2. SPINAL CORD ANATOMY
Spinal cord commences at the cervicomedullary junction within
the foramen magnum and terminates as the conus medullaris at approximately
the L1 vertebral level.
It is composed of 31 segements
-cervical (8)
-thoracic (12)
-Lumbar(5)
-sacral (5)
-coccygeal (1)

3. The cord is oval in axial section with severalgrooves identified on its surface
- the anterior median fissure contains the anteriorspinal artery
- the posterior median sulcus
- the anterior(ventral) and posterior (dorsal) nerve
roots emerge at the anterolateral and posterolateral lsulci
-outer part contains white matter and inner part
contains grey matter.
the midsagittal cord diameter is ~11 mm at C1, 10
mm from C2 to C6 and 7–9 mm below C6, usually
occupying ~40% of AP canal diameter.

5. The pia mater (meningeal covering of the cord)
continues caudally through the thecal sac as the
filum terminale and attaches to the coccyx
It normally contain some fat (fatty filum) but should
measure <2 mm in transverse dimension.
The cauda equina arises from the conus and
represents the intradural lumbar and sacral spinal
nerve roots that travel distally prior to exiting at their
respective intervertebral foramina.

6. The spinal nerves
Each spinal nerve comprises a sensory (dorsal)
root, which enters the spinal cord at each level,
and a motor (ventral) root which emerges from
the cord at each level.
The nerves are numbered according to the level
of their emergence from the vertebral canal:

7. the C1–7 nerves emerge above their respective
pedicles,
C8 emerges between C7 and T1, while the
remaining nerves emerge below their respective
pedicles
the ventral and dorsal roots combine in the
intervertebral foramen to form the dorsal root
ganglion (DRG) from which the mixed spinal
nerve arises.

8. Spinal cord tumors

9. Spinal neoplasms are divided into three groupsbased on their anatomic locations:
extradural,extramedullary-intradural, and intramedullary tumors

11. Spinal tumours may present with non-specific back
pain or vague radicular symptoms to frank
compressive myelopathy. Imaging has a key role in
identifying and characterizing the lesions, providing
an aetiological diagnosis and an anatomic roadmap
for the surgeon in this extremely challenging playing
field.

13. IMAGING APPEARANCES OF INTRAMEDULLARY
TUMOURS AND MIMICS
The “sine qua non” of IM tumours of the spine iscord expansion. The classic imaging
triad of “expansion”,“peripheral cysts” and “contrast enhancement” is almost
pathognomonic of an IM tumour.
Cysts associated with IM neoplasms may be seen at the caudal and the cranial ends of
the actual lesion or within the neoplasm. The former represent nontumoural
pathology and are postulated to arise due to obstruction of the central canal by the
mass causing CSF accumulation. These cysts do not show peripheral enhancement,
follow CSF signal intensity and regress after removal of the main tumour mass. In
contrast, intratumoural cysts are part of the neoplastic pathology, may show varying
signal (due to heterogeneity of contents) and often show peripheral contrast
enhancement.

14. Ependymoma
Ependymomas are the commonest IM tumors in adults and have a slight male
preponderance. The cervical cord is the commonest site (40%–50%) followed by the upper
dorsal cord. Ependymomas arise from the ependymal lining of the central canal of the cord
and hence have a characteristic central IM location.
MRI shows a relatively well-circumscribed, central cord mass lesion with cord expansion and
involvement of more than three spinal segments.
The lesion usually shows T2 prolongation in respect to the normal cord parenchyma. A highly
specific finding seen in about a third of lesions is the “cap sign” , which represents a peripheral
zone of hemosiderin staining due to recurrent haemorrhage and is seen on MRI as rim of T2
hypointensity (with blooming on GRE sequences). More than 75% of ependymomas are
associated with nontumoural , eccentric cysts and may also show additional syringomyelia.

17. Astrocytoma
Primary cord lesions form approximately 3% of all CNS astrocytomas. They are more
common in thesecond and third decades of life, although older age groups do not
preclude a diagnosis of an astrocytoma.
The dorsal cord is the site for approximately two-thirds of all astrocytomas followed by
the cervicalcord.
astrocytomas arise eccentrically within the cord,demonstrate poor plane of cleavage
and are
associated with both tumoural (internal) and nontumoural cysts. Most astrocytomas are
low-
grade tumours (grade I pilocytic or grade II)

21. Astrocytomas have typical features of IM tumours with cord expansion and long-
segment involvement.
The lower-grade (and more common) tumours show relatively uniform T2
hyperintensity (and T1 hypointensity). Smaller lesions may show an eccentric location
within the cord. Holocord involvement is occasionally seen. Contrast enhancement is
common but usually patchy and irregular with intralesional tumoural cysts.
Around 20% of astrocytomas may not show contrast enhancement, and there, mere
absence of enhancement should preclude the diagnosis of the entity.

22. Haemangioblastoma
Haemangioblastomas arise from a mesodermal origin cell – the haemangioblast,
which subsequently undergo embryological arrest. All tumours are highly vascular
grade I lesions with a dense network of capillary channels. They are usually eccentric
in position within the cord and characteristically arise dorsally or dorsolaterally.
The tumours are noncapsulated but demonstrate an excellent plane of cleavage,
which makes them amenable for resection, with an excellent prognosis in patients in
whom total resection is done.
On MRI, the tumours are well-circumscribed, T2hyperintense IM masses with
characteristic flow voids.

23. Intense contrast enhancement is noted. The IM lesions may present as solid nodular
enhancing foci or as cysts with enhancing nodules.
The EM compartment lesions are typically seen along the nerve roots (best noted in
the cauda equina) and show multiple foci of nodular enhancement, which may be
completely missed on routine noncontrast imaging.
Cord syrinx is common and occasionally long segments of cord oedema are seen in
associated with much smaller enhancing tumours.

26. Ganglioglioma
These are rare, benign IM tumours forming 1% of all spinal neoplasms. As in the brain, gangliogliomas
are commoner in younger ages with peak in the second decade. No gender predilection is seen.
The cervical and dorsal cord are involved with almost equal frequency The whole cord including the
conus may, however, be involved with holocord lesions also being described.
As with astrocytomas, gangliogliomas arise eccentrically within the cord and have higher association
with tumoral cysts (almost 50%) than either astrocytomas or ependymomas.
Imaging Features
Bony changes such as scoliosis are seen .The combination of glial and neuronal elements often
contributes to a mixed signal intensity on T1-weighted images while they show relatively homogeneous
T2 signal. Haemorrhage and flow voids are not seen. Contrast enhancement is patchy though somewhat
less vivid than astrocytoma or ependymomas. In around half the cases, associated pial enhancement
may suggest a diagnosis of ganglioglioma

28. Atypical Teratoid Rhabdoid Tumours
ATRTs are rare WHO grade IV seen almost exclusively in the pediatric population.
These tumors are histologically bizarre containing elements of both neuro and surface
ectoderm and mesenchyme with an abundance of the eponymous “rhabdoid” cells.
ATRT can be seen at extraaxial location with even primary plaque-like meningeal
spread having been described.
On MRI, the characteristic heterogeneous T2 signal along with features of
hypercellularity (T1 isointensity and diffusion restriction) should alert the radiologist
to consider this diagnosis. Imaging of the entire craniospinal axis mandatory to rule
out meningeal or distant intraaxial metastases

29. Lymphoma
Spinal involvement in lymphoma is usually due to contiguous involvement from a
paraspinal lymph nodal mass or bony involvement in lymphoma.
Occasionally, lymphoma may cause diffuse meningeal involvement (meningeal
carcinomatosis), which will be dealt with in detail later in this section.
Imaging in primary cord lymphoma mimics an LETM with variable length of cord
hyperintensity on T2 along with contrast enhancement.
As lymphoma is uncommon, inflammatory and infective pathologies are often
considered first and even treated empirically to no effect. Skip lesions involving both
the cord and brain have been described.

30. Intradural–Extramedullary Lesions
Scoliosis may be seen with apex at the levels of the tumours.
Larger tumors may show spinal canal widening, bony erosions and remodelling. Rarely large
paraspinal soft-tissue mass lesions may be seen as in the case of type I NF.
These lesions displace and compress the cord with a widening of CSF spaces on the side of the
lesion giving rise to “meniscus sign”.
Drop metastases from intracranial neoplasm are the most common intradural extramedullary
lesion in the paediatric age group. (Eg : Medulloblastoma)
Myxopapillary ependymoma,
Nerve sheath tumours such as neurofibroma, schwannoma and meningeal tumours
Other tumours or tumour-like conditions in this location include epidermoid/dermoid cyst.

31. Myxopapillary Ependymoma
These tumours are of ependymal origin but occur near conus and filum terminale and
present as intradural extramedullary mass.
On imaging,they are heterogeneous mixed solid cystic lesions. These lesions are often
associated with haemorrhage, which can lead to super cial siderosis. Tumour

heterogeneity is due to haemorrhage, cystic changes and mineralization.
Heterogeneous contrast enhancement is seen. The slow-growing lesion can cause
scalloping of vertebral bodies

32. Myxopapillary Ependymoma

33. Myxopapillary Ependymoma

34. Nerve Sheath Tumours
These are benign tumours arising from the nerve sheath and fibroblasts present in
the nerve.
They can occursporadically or may be associatedwith phakomatosis.
These tumours are less common in children as compared with adults.
Two common types of nerve sheath tumours are schwannoma and neuro bromas.


35. Schwannoma
They arise from the Schwann cells and grow eccentrically in relation to the nerve.
Usually have a well-defined capsule separating them from the underlying nerve.
They can occur in intradural, extradural or combined intra–extradural location.
Multiple schwannomas are associated with neurofibromatosis Type 2.
Imaging features
Well-defined lesions which are hypointense on T1WI and hyperintense on T2WI and show avid
homogeneous contrast enhancement.
Cystic changes may be seen.
Tumours extending in both intradural and extradural compartment appear “dumbbell” in shape

38. Neurofibroma
They arise from the Schwann cells and fibroblasts and have a tendency to infiltrate
the nerve root.Do not have a well-defined interface between the lesion and the
underlying nerve.
These tumours can also occur in intradural, extradural or combined intra–extradural
location.
The two morphologic types are fusiform (arising from a single nerve fascicle) and
plexiform (involving multiple nerve branches).
Multiple neurofibromas are associated with neurofibromatosis type 1.

39. Neurofibroma
Imaging features
They have variable T1 signal, are T2 hyperintense and enhance after contrast
administration.
Well-defined lesions which are hypointense on T1WI and hyperintense on T2WI and
show avid homogeneous contrast enhancement.
Characteristic feature when imaged in cross section is “target sign” – central low
signal with peripheral high signal) on T2W images.
Plexiform neurofibromas affecting multiple nerve roots can give rise to a “string of
bead” sign

42. Dermoid Tumour
It has all the three dermal layers and contains skin appendages; e.g. hair, and
sebaceous glands. Can be associated with a dermal sinus tract. Mixed solid and cystic
lesion.
Imaging features
MR appearances vary depending on the composition of the lesion. Cystic areas may
be hyperintense on T1 and iso- to hypointense on T2WI. Solid areas appear
hypointense on T1 and hyperintense on T2WI. They are characterized by the
presence of macroscopic fat. Do not show contrast enhancement unless secondarily
infected

44. METASTASES FROM INTRACRANIAL
NEOPLASMS
Spinal metastases by CSF dissemination from primary intracranial neoplasms are
more common in children as compared with adults.
Medulloblastoma is the most common neoplasm to disseminate in this way. Other
neoplasms that exhibit CSF dissemination are ependymoma, high-grade gliomas,
germinomas, choroid plexus tumours and pineal parenchymal tumours
(pineoblastomas and pineocytomas).
These metastases are mostly leptomeningeal in location.
Imaging Features Spinal metastases appear as diffuse or nodular enhancing lesions
involving the surface of cord and nerve roots. They might appear as “sugar coating”
on the surface of cord as classically described in medulloblastoma.

45. Epidermoid Tumour
It has only two dermal layers and does not contain skin appendages.
Apart from being congenital, they can be acquired due to implantation of skin debris
during surgery or posttrauma. More of a cystic lesion.
Imaging features
They are more homogeneous, follow CSF signal intensity on T1 and T2WI. Appear
bright on diffusion images that help differentiate from the arachnoid cyst. Do not
show contrast enhancement

47. MENINGIOMAS
Meningiomas are uncommon in children comprising only 1%–2% of spinal tumours.
Spinal meningiomas can be associated with neurofibromatosis type 2.
They are mostly intradural.However, they can also present as extradural masses. On
imaging, they are dural-based sharply marginated lesions which appear hypointense
to isointense on T1WI, hyperintense on T2WI, and show homogeneous contrast
enhancement. They may contain calcifications.

48. MENINGIOMAS

49. Paraganglioma
CNS paragangliomas are embryologically similar to their extra CNS counterparts in the
adrenal medulla and carotid body in that they originate from the neural crest cells.
The classic site is the filum terminale and conus medullaris
Small tumours typically present with pain, while larger lesions manifest with cauda
equina syndrome. Occasional intralesional haemorrhage may cause sudden
paraplegia Endocrine symptoms are extremely rare.
The lesions are isointense on T1WI and hyperintense on T2WI. Intralesional flow voids
are common but not specific. The typical salt and pepper appearance described in
head and neck paragangliomas is uncommon in lesions of the conus. Sequelae of
haemorrhage and the cap sign may be seen occasionally. Intense contrast enhance

51. Extradural Lesions
In the paediatric age group, these tumours comprise almost 65% of all the spinal
tumours.
These can be divided into primary osseous tumours, nonosseous extradural lesions
such as haematological malignancies, and extraspinal tumours with secondary spine
involvement such as neuroblastoma.
Apart from arriving at the imaging diagnosis, the role of imaging is to document the
extent of the lesion, assess degree of cord compression and evaluate for the stability
of the spinal column.

55. Thank you