HEAD AND NECK IMAGING EHAB ABOU ELFOTOUH. MD.

ORBITAL IMAGING VI

Orbital pseudotumor: Orbital pseudo-tumor is one of the most

common causes of unilateral proptosis. It is generally a disease of middle age and has

an acute onset. A painful ophthalmoplegia and edema of the

eyelid or conjunctiva are present in 50% of the patients.

Regression with steroid therapy is considered a specific sign of the disease.

Pseudoturnor may involve any or all intra-orbital structures.

Orbital pseudotumor: Non-granulomatous orbital inflammatory

process. The second most common cause of

exophthalmos. Infiltrative or mass like soft tissue seen

invading any orbital structure. irregular margins and extends across

multiple compartments. May mimic neoplasm or aggressive infection. May extend intra-cranially.

Orbital pseudotumor: Categorized by areas of involvement:

A- Myositic pattern:

* Most common pattern.

* Involving any muscle and mutiple muscle on 50%.

* Involving tendinous insertion with tubular configuration.

B- Lacrimal pattern:

* 2nd most common type.

* Diffuse oblong enlargement, particularly antero-posterior dimension.

Orbital pseudotumor:

C- Anterior (eye and retrobulbar fat) pattern: *3rd most common type. * Variable involvement of retro-bulbar fat and nerve. *Uveal-scleral form shows thickened sclera and shaggy

enhancement. * Peri-neuritic form shows irregular nerve sheath

thickening and enhancement.D- Diffuse (intra-conal- multi compartement) pattern: *Overlap with anterior and other pattern. *Frequently tume-factive and mass like appearance.

Orbital pseudotumor:

E- Apical (apex, intra cranial) pattern:

* Less common, involves orbital apex with posterior extension through fissure.

* Tolosa-Hunt syndrome considered intra-cranial variant with extension through cavernous sinus.

Orbital pseudotumor: CT imaging: Focal & infiltrative. Poorly circuscribed. Mass or thickening on

muscle, lacrimal and orbital structures.

Moderate diffuse enhancement.

Increase attenuation on late enhancing phase.

Orbital pseudotumor:

Orbital pseudotumor: MR imaging: Hypointense tonormal

muscle on TIWIs. Iso-intense to slighly

hyper-intense on T2WIs and STIR.

Due to high cellular component and fibrosis.

Marked diffuse in-homogenous enhancement.

Orbital pseudotumor:

Orbital pseudotumor:

Orbital pseudotumor:

Graves ophthalmopathy: Is the most common cause of exophthalmos in adults. Graves ophthalmopathy usually occurs 5 years

after the onset of thyroid disease. Autoimmune inflammation condition associated with

thyroid dys-function. Classically spindle-shaped enlargement of the

extra-ocular muscles is observed, with sparing of the tendinous insertion.

The inferior, medial, superior, and lateral rectus muscles (listed in order of decreasing frequency of involvement) may be involved.

Graves ophthalmopathy: These findings are usually bilateral (90%)and

symmetric (70%). Isolted muscle involvement on 5%, particularly

superior rectus. Additional imaging findings include increased

orbital fat, lacrimal gland enlargement, eyelid edema, stretching of the optic nerve, and tenting of the posterior globe.

Treatment is primarily conservative, with radiation therapy reserved for reduction of tension on the optic nerve.

Graves ophthalmopathy: CT imaging: Iso-dense enlargement

of EOMs. Heterogeneous low

density area contents. Hypertrophied retro-

bulbar fat. Heterogeneous

increased enhancement of involved muscles.

Graves ophthalmopathy:

Graves ophthalmopathy:

Graves ophthalmopathy: MR imaging: Isointense

enlargement of EOMs on T1WIs.

Increase EOM signals on acute phase and decrease signal on chronic phase on T2WIs and STIR.

Heterogeneous enhancement of involved muscles.

Graves ophthalmopathy:

Graves ophthalmopathy:

Optic Neuritis: Two type of acute ON : A- MS associated ON. B- Idiopathic isolated mono-symptomativ ON.*Diffuse only enlargement of optic nerve with central or

peripheral enhancing pattern.*Unilateral on 70%.*segments of nerve involvement: a- Anterior intra-orbital.45%. b- Mid intra-orbital 60%. c- Intra-canalicular 35%. d- Pre-chiasmatic and chiasma 7%.

Optic Neuritis: CT imaging: Usually normal. May show minimal

optic nerve enlargement.

On post contrast imaging, segmental enhancing criteria.

Optic Neuritis: MR imaging: Mildly enlarged optic

nerve with ill defined border on T1WIs.

Enlarged optic nerve with egmental bright signal on T2WIs and STIR.

Central or peripheral tram track enhancing pattern on post contrast imaging.

Optic Neuritis:

Optic Neuritis:

Optic Neuritis:

Lympho-proliferative lesions of the orbit: LPLO spectrum including benign and malignant

tumors: A- Lymphoidal hyperplasia 10-40%: * Reactive or hyperplasia. B- Lymphoma (NHL) 60-90%.* Homogenus enhancing mass lesion any where on the

orbit.* Lobulated well defined margins.*May be have infiltrative presentation pattern or

associated inflammatory changes.

Lympho-proliferative lesions of the orbit: Locations:A-Anterior extra-conal orbital space, centered on

superior temporal quadrant.B- Lacrimal gland.C- Diffuse infiltrative pattern with intra-conal

component and peri-neural involvement.D- Intra-cranial extension with predilection for

pituitary stalk.* Bilateral presentation in 25%.* Multifocal within orbital region in less than 5%.

Lympho-proliferative lesions of the orbit: CT imaging: Iso dense to slightly

hyper-dense. Homogenous on

malignant lymphoma. In-homogenous on

hyperplasia. Rare calcification in

less than 5 %.

Lympho-proliferative lesions of the orbit: Moderate diffuse

enhancement.

Followed by decrease enhancement on delayed scan.

Lympho-proliferative lesions of the orbit: MR imaging: Homogenous mildly

hyper-intense to muscle on T1WIs.

mildly hyper-intense on T2WIs and STIR.

Moderate to marked homogenous enhancement.

Lympho-proliferative lesions of the orbit:

Lympho-proliferative lesions of the orbit:

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