Post on 10-May-2015
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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