Orbit and Visual Pathway imaging strategies Jalal JalalShokouhi-M.D. jalaljalalshokouhi@hotmail.com

X-RAY US CT

Orbit • Configuration of orbital cone • Contents: - Globe (positio; size, density, wall thickness) - Eye muscles (position, course, density, width) - Optic nerve (course, width) - Ophthalmic vein (course, width)

Checklist Orbits • Symmetrical • Normal size • Normal orbital cone Orbital walls • Smooth, sharp borders • No bone destruction • No circumscribed widening of bone or softtissue components

Globe • Position • Symmetry • Size • Spherical

Ocular contents • Density Ocular wall • Borders (smooth and sharp) • Uniform thickness Optic nerve • Normal caliber • Course

Eye muscles • Position • Width • Course Retrobulbar fat • Clear • No masses

Ophthalmic vein • Course • Caliber Lacrimal gland • Size • Symmetry • No unilateral or bilateral enlargement • Position No excavation or destruction of adjacent bone • Homogeneous internal structure • No hypodense areas • Smooth borders

Neurocranium • Temporal lobes • Frontal lobes Paranasal • Maxillary sinuses sinuses • Ethmoid cells

MRI

Orbits • Shape (orbital cone) • Size • Symmetry • Orbital walls: - Borders (smooth and sharp) - No bone destruction - No circumscribed expansion of bony or softtissue components of the orbital wall

Globe • Shape (spherical) • Size Position Symmetry • Ocular contents: - Signal intensity (fluid-equivalent) • Ocular wall: - Borders (smooth and sharp) - Thickness • Retrobulbar fat (clear) • No masses

Optic nerve • Caliber Course Eye muscles • Position • Width Course Ophthalmic vein • Course • Caliber

Lacrimal gland • Size • Symmetry • No unilateral or bilateral enlargement • Position No excavation or destruction of adjacent bone • Homogeneous internal structure • No hypointense or hyperintense changes • Smooth borders

Neurocranium • Temporal lobes • Frontal lobes Paranasal sinuses • Maxillary sinuses • Ethmoid cells

Exophtalmus

Differential Diagnosis: Orbital Swelling • Orbital infection (bacterial, viral, fungal) • Orbital inflammation: orbital pseudotumor; granulomatous diseases (sarcoid, Wegener's granulomatosis); vasculitides, connective tissue disorders Diagnosis Orbital cellulitis (serratia isolated on culture)

Differential Diagnosis: Lacrimal Gland Mass • Lymphoid/Inflammatory: acute (viral, bacterial, orbital pseudotumor, lymphoma) or chronic (sarcoid, Wegener's, thyroid opthmalopathy, Sjbgrens's syndrome, Mickulicz syndrome) • Epithelial neoplasms: pleomorphic adenoma or malignant tumors (adenoid cystic carcinoma, mucoepidermoid carcinoma, adenocarcinoma) Diagnosis Lacrimal gland enlargement due to acute dacroadenitis

Differential Diagnosis: Enlargement of the Extraocular Muscles • Infection (bacterial, viral or fungal) • Thyroid orbitopathy • Inflammatory conditions: orbital pseudotumor, Sjogrens's syndrome, Mickulicz's syndrome, granulomatous conditions (sarcoid, Wegener's granulomatosis), connective tissue disorders (rheumatoid arthritis, lupus, scleroderma), retained foreign bodies • Vasculitides (PAN, giant cell arteritis) • Tumors: hemangioma, rhabdomyoma, plasmacytoma, lymphoma, leukemia, rhabdomyosarcoma • Amyloidosis Diagnosis Orbital pseudotumor

Differential Diagnosis: Extraocular Muscle Enlargement • Endocrine • Thyroid ophthalmopathy • Acromegaly • Inflammatory • Pseudotumor • Infection: bacterial, fungal, parasitic (cysticercosis, trichinosis) • Plasma cell granuloma • Sarcoid • Neoplastic • Benign: rhabdomyoma • Malignant: lymphoma, rhabdomyosarcoma, metastatic disease • Vascular • Carotid cavernous fistula • Extradural arteriovenous fistula • Deposition diseases: amyloid Diagnosis Thyroid orbitopathy

Differential Diagnosis: Diffuse Hyperintensity in the Extra- and Intraconal Fat on FAT SAT TIWI • Artifactual: artifact due to failure of fat suppression • Pathologic: orbital pseudotumor, orbital cellulitis, orbital neoplasm Diagnosis Artifact due to asymmetric failure of fat-suppression

Differential Diagnosis: Optic Nerve Enlargement and Enhancement (Optic Neuritis) • Demyelinating disease': multiple sclerosis • Inflammatory: collagen vascular disease, orbital pseudotumor, sarcoid • Infectious: HIV-related optic neuropathies, tuberculosis, fungal infection, toxoplasmosis, syphilis • Neoplastic': optic glioma, optic nerve meningioma, metastasis, leptomeningeal carcinomatosis • Vascular': ischemic neuropathy (severe hypertension, systemic vasculopathies) • Others: radiation induced optic neuropathy, optic nerve trauma Note: ' indicates that the process is usually unilateral.

Diagnosis Radiation-induced optic neuropathy

Diagnosis Cavernous hemangioma Differential Diagnosis: Retrobulbar Intraconal Mass • Hemangioma • Schwanoma • Metastasis • Pseudotumor • Meningioma • Hemangiopericytoma • Lymphangioma • Varix • Hematic cyst Diagnosis Cavernous hemangioma

Differential Diagnosis: Enlargement of the Optic Nerve or Sheath • Tumors: optic nerve glioma, optic nerve meningioma, optic nerve neuroma, lymphoma, leukemia (chloroma), metastasis (hematogeneous: breast and lung, direct invasion: retinoblastoma, uveal melanoma), hemangioblastoma, hemangiopericytoma • Inflammatory lesions: orbital pseudotumor, optic neuritis, sarcoidosis • Others: pseudotumor cerebri Diagnosis Intraorbital meningioma

Differential Diagnosis: Choroidal Mass • Melanoma • Hemangioma • Hemorrhage • Retinal/choroidal detachment • Choroidal metastasis • Sarcoidosis • Retinal cyst • Retinoblastoma • Retinal gliosis • Nevi • Leiomyoma • Schwanoma • Neurofibroma Diagnosis Choroidal (uveal) melanoma

Differential Diagnosis: Intraocular Mass in a Child • Neoplastic conditions: retinoblastoma and retinocytoma", uveal melanoma, metastases (neuroblastoma, most common), pseudoglioma (retinal astrocytoma or astrocytic hamartoma) • Nonneoplastic conditions: persistent hyperplastic primary vitreous (PHPV), retinopathy of prematurity or retinal dysplasia (ROP)", Coat's disease, toxocariasis or larval granulomatosis", chronic retinal detachment", uveitis Diagnosis Retinoblastoma

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