HEAD AND NECK IMAGINGEHAB ABOU ELFOTOUH. MD.

ORBITAL IMAGING III

Retinal and Choroidal Detachments:

Retinal detachment may be either rhegmatogenous or nonrhegmatogenous.

A rhegmatogenous retinal detachment is a full-thickness tear of the retina and movement of liquefied vitreous into sub-retinal space.

Nonrhegmatogenous retinal detachment ,result of traction on the retina .

ORBITAL TUMOR:

Retinal Detachment:characteristic V-shape.

The pex at the optic disc on cross-sectional images.

MR imaging can differentiate serous, proteinaceous, hemorrhagic content on sub-retnal space.

Fluid accumulation in the subchoroidal space.

Condition that may occur after ocular surgery, trauma or an inflammatory choroidal process (uveitis).

spares the region of the optic disc, in the posterior third of the globe.

Choroidal Detachment:

Retinoblastoma most common intraocular tumor of childhood.

Aggressive malignant tumor from the immature retina.

Manifests before the age of 5 years (90%–95%).Accounts for 11% of all cancers in the first year

of life.Both heritable and nonheritable forms of

retinoblastoma.Bilateral (20%–34%) or multifocal tumors occur

in patients with heritable retinoblastoma.

Retinoblastoma:

Retinoblastoma:Leukocoria: the

normal red reflex of the retina is replaced by a yellowish or grayish white color, occurs in 56%–72%.

Strabismus (lack of binocular vision) 22%–24%.

Imaging Findings:Presence of calcifications differentiating

retinoblastoma from other intraocular lesions.

Exophytic growth component can involve the sub-retinal space.

Retinal detachment.

Cystic spaces reflecting common pathologic finding of necrosis.

Retinoblastoma:

Endophytic tumor grow from the inner, sensory retina toward the vitreous.

Exophytic tumor growth from the outer retinal surface toward the choroid.

Mixed endophytic and exophytic tumor growth.

diffuse, infiltrating growth with plaquelike thickening of the retina, in only 1%–2%, with lack calcium deposits.

Complete spontaneous regression, end state as shrunken, nonfunctioning globe.

Different growth patterns of retinoblastoma:

CT is the primary modality for evaluation of children with leukocoria.

Hyper-attenuating mass in the posterior globe.Calcifications are apparent at CT in 95% of cases.Smooth or irregular margins.Extend into the vitreous or the subretinal space,

causing retinal detachment.Contrast enhancement is seen in 27.5% of cases.

Retinoblastoma:

MR imaging : more sensitive for extension .retinoblastoma follows the signal intensity of

gray matter.At T1-weighted imaging, slightly hyper-

intense to the ipsilateral vitreous.At T2-weighted imaging, commonly dark

compared to the vitreous.Calcification make the tumor appear

heterogeneous.Tumor has heterogenous enhancing pattern.

Retinoblastoma:

Retinocytoma:Well differentiated,

benign form of the tumor.

Well circumscribed and has a smooth surface.

No calcification.

Non neoplastic lesions that also cause leukocoria, include :

Persistent Hyperplastic Primary Vitreous (PHPV) .

Coats disease.

Larval granulomatosis.

Retinopathy of prematurity.

Retinal astrocytic hamartoma.

Pseudoretinoblastoma:

Persistence and hyperplasia of fibrovascular tissue from embryonic primary vitreous.

Persistent hyaloid artery may be seen within the Cloquet canal.

Second most common cause of leukocoria, accounting for 19%–28%.

Persistent Hyperplastic Primary Vitreous:

Microphthalmos, with absent calcification.Variably sized cone-shaped retro-lental focus of

increased attenuation.At the apex, a linear band or septum extending

to the posterior pole.Increased attenuation of the entire vitreous

body.Layered attenuating hemorrhage may be seen

in the globe on subretinal or sub hyaloid space. Lens appear abnormally small, lucent, or

rounded due to absorption or swelling.

Imaging Findings, CT SCAN:

Superior imaging modality for diagnosis of PHPV.

Microphthalmos.

Small retro-lental masses .

Anterior tenting of the retin.

Post contrast imaging showing enhancement of the retrolental primary vitreous.

Imaging Findings, MRI:

A congenital, nonhereditary, unilateral vascular malformation of the retina with telangiectasis and aneurysm formation.

Breakdown in the blood-retina barrier.Fluid contains cholesterol crystals and

lipidladen macrophages.Accumulation of lipo-proteinaceous fluid. Thickened retina.Massive exudative retinal detachment.

Coats Disease:

Increased attenuation in globe compared to normal vitreous.

No calcification.

globe appears normal in size.

Post contrastintravenous, linear enhancement of the anterior margin of the subretinal exudate, corresponding to the thickened retina with V-shaped configuration.

subretinal space does not enhance.

Imaging Findings, CT:

subretinal exudate has uniform high signal intensity on both T1- and T2-weighted imagesdue to its high fat content.

Hemorrhage or fibrosis may confer a heterogeneous appearance, especially on T2-weighted images.

subretinal space does not enhance.

Mild to moderate linear enhancement at the border between the exudate and the remaining vitreous.

Imaging Findings, MRI:

Toxocara Endophthalmitis:Ocular larva migrans, a granulomatous reaction

in the vitreous or uvea in response to infestation by the larval form of nematode T canis or T cati.

CT may demonstrate high attenuation withor without a discrete mass.

Absence of calcification.Size of the globe is normal.Secondary retinal detachment is frequently

visualized.No enhancement.

At MR imaging, a central vitreous mass is usually visualized.

Isointense to vitreous on T1-weighted images.Hyperintense or isointenserelative to vitreous

on T2-weighted images.Sub-retinal exudate may be seen with

variable signal intensity.Moderate to marked enhancement.

Toxocara Endophthalmitis:

THANKS