ORBITAL IMAGING V

HEAD AND NECK IMAGING

EHAB ABOU ELFOTOUH. MD.

Optic Nerve Enlargement D.D:

Neoplasms: Optic nerve glioma. Meningioma. Hemangioblastoa. Schwannoma. Ganglioglioma. Medulloepitheliomas

. Metastasis. Leukemia.

Nonneoplastic: Increased intracranial

pressure. Optic neuritis. Graves disease. Orbital pseudotumor. Toxoplasmosis. Tuberculosis. Sarcoidosis. Central retinal vein

occlusion. Traumatic hematoma of

the optic nerve.

Optic Nerve Glioma: Optic nerve gliomas are histologically juvenile pilocytic

astrocytomas, WHO grade I.

May involve any portion of the optic pathways as well as the hypothalamus.

Representing 4% of orbital tumors.

Usually manifested in the first decade of life.

The most common intraconal tumor of childhood.

More than half of patients have neurofibromatosis type 1 (NF1).

Optic Nerve Glioma: CT Imaging Findings: Imaging depends on the

macroscopic growth pattern of the tumor.

Allows good evaluation of the optic nerve due to the intrinsic contrast between the nerve and the conal fat.

But is less sensitive than MR imaging for intracranial extension.

Optic Nerve Glioma: Fusiform enlarged

optic nerve.

kinking or tortuosity of its course.

Iso- to slightly hypo attenuation.

May be eccentric or a discrete mass seen from the nerve.

Optic Nerve Glioma: High attenuation or

calcification are rare.

Enlargement of the optic canal.

Enhancement is variable.

Cystic tumors show enhancement of its wall.

Optic Nerve Glioma: MR imaging: Better shows intracranial

extent.

Coronal and axial thin-section of T1, T2 and fat suppression.

Screening examination of the brain.

Post contrast T1 and fat supp. images.

Optic Nerve Glioma: Fusiform or less commonly

eccentric globoid, enlargement of optic pathway.

iso- to hypointense to the optic pathway on TIWIs.

slightly hyperintense on T2WIs.

Areas of hemorrhage or calcification are rare.

Optic Nerve Glioma: Enhancement with IV

gadolinium is variable. Posterior extension may

at seen only at post IV contrast imaging.

Isolated optic nerve glioma more common in patients with NF1.

Optic pathways extension more common in children without NF1.

Optic Nerve Glioma:

Optic Nerve Glioma:

Optic Nerve Glioma:

Optic Nerve Glioma:

Optic Nerve Glioma:

Optic Nerve Sheath Meningioma: Meningiomas primarily in the optic nerve sheath are

even rarer than glioma. Mostly often in middleaged women. Bilateral optic nerve sheath meningiomas are rarely

and association with neurofibromatosis. Predominant early feature is visual loss. Proptosis occurs later. Physical examination reveals an abnormal optic

disk, which may be swollen or atrophic. Visual field revealed usually a central scotoma. Restriction of eye movement.

Optic Nerve Sheath Meningioma: CT findings: Segmental or diffuse

thickening of the optic nerve.

Fusiform but uniform thickening of nerve sheath more common.

Normal optic nerve running through the tumor, have ‘ ‘tram-track’ ‘ appearance on axial images.

Optic Nerve Sheath Meningioma: In coronal views a

“donut” configuration, with a ring of high density around nerve.

Low-density normal nerve surrounded by the higher density tumor.

This finding can differentiating meningioma from glioma.

Optic Nerve Sheath Meningioma: Calcification is

uncommon but more frequent than in gliomas.

Enhanced on post contrast imaging.

Optic canal widening may be demonstrated.

Typical hyperostosis of adjacent bones.

Optic Nerve Sheath Meningioma: MRI findings: Better for assessment of

intra-cranial extension.

Segmental or diffuse enlargement.

Fusiform thickening.

On T1WIs, iso-signal with gray matter.

On T2WIs, iso to slight bright signals.

Optic Nerve Sheath Meningioma: O post contrast, intense

enhancing criteria.

‘tram-track’ on axial imaging.

“doughnut” configuration on coronal scan.

Intra-cranial extension better detected on post contrast scan.

Optic Nerve Sheath Meningioma:

Thank you