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Graves' Orbitopathy

Anterior Chamber Perforation 6. Ocular Lens Displacement 7. Ruptured Globe 8. Phthisis Bulbi 9. Ocular Prosthesis Orbital Cavernous Hemangioma Optic Nerve Glioma Optic Nerve Meningioma Posterior Orbital Dermoids Orbital Lipoma Occular Adnexal Lymphoma Ocular Melanoma Retinoblastoma Orbital Leukemia Optic Nerve Metastasis Rhabdomyosarcoma Rhabdomyosarcoma Part IV Congenital Coloboma Persistent Hyperplastic Primary Vitreous Congenital Orbital Teratoma Congenital Anophthalmia Part V Vascular Magnetic resonance imaging shows intraconal hypointense, rounded well-circumscribed mass lesion asterisk on sagittal T1WI A , hyperintense on short tau inversion recovery B , T2WI C with few hypointensities of flow voids arrow with intense enhancement on post-contrast gadolinium enhanced T1W FS images D.

Capillary hemangiomas present in infants within first year of life and then tend to diminish in size from the time of presentation due to gradual involution. These masses show intense enhancement in the early phase with early washout of the contrast in delayed phases. Capillary hemangioma. Axial T2WI A demonstrates an irregular hyperintense lesion asterisk involving right orbit extending into anterior periocular tissues curved arrow enhancing well on contrast gadolinium administration seen on T1WI coronal B , axial C images.

Other vascular lesions include lymphangioma [ Figure 21 ], veno-lymphatic, and arteriovenous malformations. Carotid-cavernous fistula causes pulsating exophthalmos, with engorgement of superior ophthalmic vein SOV which can be very well visualized on CT and MRI [ Figure 22 ].

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However, in the late stages there can be stenosis due to thrombosis of the SOV. Multiseptate, multilobulated lesion left orbit asterisk , with multiple fluid-fluid levels within multiple locules arrow appears hypointense to orbital fat, hyperintense to brain on axial T1W A , markedly hyperintense on axial T2WI B and coronal short tau inversion recovery images C. Carotid cavernous fistula left. MR is the modality of choice for imaging of the entire visual pathway from its origin at the posterior point of the globe to the visual cortex.

The intracanalicular portion is not well visualized on CT due to the dense cortical bone at the apex[ 1 ] and is displayed very well on MR. The intracranial ON, optic chiasma, and tracts are well visualized on coronal and sagittal MR[ 18 ] and appear isointense to cerebral white matter.

The optic radiation is within the white matter of temporoparietal and occipital lobes extending upto the calcarine cortex primary visual cortex flanked by the easily identified calcarine sulcus on the medial aspect of the occipital lobe. Intraorbital gliomas appear early within first decade of life, presenting with painless proptosis, usually with associated loss of vision. Calcification is usually absent. Bilateral lesions are seen in Neurofibromatosis NF Type 1,[ 20 ] thus entire visual pathway should be evaluated. MR is more sensitive and 3mm thin sections are recommended which can avoid missing small lesions in the intracanalicular portion.

Usually, it appears hypointense to orbital fat on T1WI isointense to cerebral cortex , it is hyperintense to cortex, white matter and fat on T2WI. Post-contrast enhancement is common except in areas with cystic changes,[ 19 — 21 ] [ Figure 23 ]. Sometimes, the tumor grows circumferential around the ON into the perineural space to mimic a perioptic meningioma[ 1 ] [ Figure 24 ].

Optic nerve glioma. T2WI sagittal A shows fusiform enlargement optic nerve asterisk with hyperintense perineural meningeal circumferential thickening arrow on short tau inversion recovery coronal T2WI B arachnoid gliomatosis in optic nerve glioma and significant enhancement curved arrow on T1W FS image C.

Post-contrast T1W FS axial A , coronal B , Sagittal C showing smooth fusiform expansion of optic nerve sheath complex asterisk with diffuse homogeneous enhancement extending posteriorly through the apex arrow along the visual pathway curved arrow suggestive of optic nerve glioma. These are usually benign tumours arising from the meningo endothelial cells with a higher incidence in females They commonly occur in the 4 th -5 th decade, however if they are found in children, a possibility of Neurofibromatoses type II needs to be kept in mind. The patterns usually seen on imaging are as an eccentric localized mass on one side of the optic nerve or circumferential along the length as thickening or fusiform enlargement of the ONSC.

It may cause bony hyperostosis and optic canal enlargement[ 19 , 20 ] [ Figure 25 ]. Perioptic meningioma. Thin sections axial computed tomography shows A tramtrack calcification along right optic nerve sheath complex thin arrow , hyperostosis at optic canal thick arrow. Post-contrast perineural enhancement noted B.

Optic nerve sheath complex meningioma. Magnetic resonance short tau inversion recovery coronal A , sagittal post-contrast fat suppression T1WI B , left intraconal mass with fusiform thickening of perineural portion of optic nerve sheath complex compressing the nerve arrow splaying of muscle cone showing diffuse enhancement.

Orbital imaging

Acute inflammation causes enlargement of ON due to infections by micro-organisms causing papillitis, or following viral infections due to immune mechanisms parainfections. FS T1WI pre-and post-contrast images are useful in optic neuritis and demonstrates localized or diffuse enhancement within the nerve [ Figure 28 ]. Brain and spine MRI is usually required in combination while evaluating patients of demyelinating diseases such as MS. A, B Optic neuritis.

Imaging of Orbit I - DRE 7 - Dr Mamdouh Mahfouz

Magnetic resonance short tau inversion recovery coronal images show increased signal intensity of optic nerve sheath complex with slightly enlarged nerve arrow Normal optic nerve measures mm. Optic Neuritis in multiple sclerosis. Axial T1WFS image showing enhancement of segment of left intraorbital curved arrow optic nerve extending posteriorly involving the intracanalicular portion arrow. The orbit may be secondarily involved due to invasion of malignant tumors from the surrounding structures, most commonly malignancy from sino-nasal cavities [ Figure 29 ] or due to metastatic deposits from known or unknown primary.

In the pediatric age group, neuroblastoma is one of the commonest primary tumors that metastasise to the orbits. Orbital involvement in sinonasal malignancy.

Multimodality imaging of the orbit

Coronal computed tomography A shows expansile enhancing mass asterisk in sinonasal cavity right causing erosion of adjacent orbital bony walls B and extension into right orbit arrow. Diffusion weighted imaging DWI MRI with apparent diffusion coefficient ADC values and ratios are being increasingly used to analyze molecular diffusion at the cellular level in head and neck imaging, especially in cancers. Retinoblastoma is the commonest intraocular tumor of childhood usually presenting below 5 years and is thought to be congenital in origin. Clinically, leucocoria[ 27 ] is associated with proptosis, which may be bilateral.

The main patterns of the lesion are exophytic, endophytic or diffuse type. CT and MRI are very useful in determining retrobulbar and extraocular spread, intracranial involvement, and exclude trilateral retinoblastoma with pineal gland tumors when bilateral disease is detected. On MR, they are hyperintense to normal vitreous on T1WI, moderate to markedly hypointense on T2WI depending on the calcification [ Figure 31 ], demonstrated well with contrast administration and thin sections 1.

It is important to differentiate the tumor from persistent hyperplastic primary vitreous PHPV [ Figure 32 ], retinopathies of prematurity ROP , Coats' disease primary retinal telengiectases , organized subretinal hemorrhage, endophthalmitis, and other intraocular masses. Bilateral retinoblastomas.

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Axial computed tomography CT scans A showing bilateral intraocular soft tissue density mass lesions curved arrow with specks of calcifications arrow. Follow-up CT B shows chunky calcifications with shrunken globe pthisis bulbi left arrow. Magnetic resonance axial T1WI A shows a left intraocular mass arrow hyperintense to vitreous and markedly hypointense to vitreous curved arrow on axial T2WI B.

Persistent hyperplastic primary vitreous right. These are highly malignant tumors arising from the uvea choroid, ciliary body, iris , that tend to metastasize hematogenously to liver, lung, bone, kidney, and brain. Imaging must focus to search for metastatic spread which guides management.

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CT reveals a hyperdense, well-marginated, typically enhancing mass and should to be differentiated from other primary and secondary uveal and choroidal tumors. On MR, the lesions are of moderately high signal on T1W paramagnetic properties of melanin or hemorrhage [ Figure 33 ], and are hypointense on T2W. Gd contrast is used for evaluation of ON and retrobulbar extension. Ocular melanoma. T1WI sagittal A , axial B shows hyperintense ring shaped posterior intraocular uveal lesion curved arrow paramagnetic effect of melanin.

Lacrimal gland is located in the lacrimal fossa in the superolateral, extraconal compartment adjacent to superior and lateral rectus tendons].

Inflammatory diseases are usually acute, may be a part of spectrum of orbital pseudotumor or related to trauma. MR T1W, T2W coronal, axial images shows hypointense enlarged left lacrimal gland enlargement black arrow with prominent enhancement white arrows seen on post-contrast gadolinium enhanced T1W FS images suggestive of dacryoadenitis, mimics inflammatory pseudotumor.

Lymphomatous processes may be unilateral or bilateral, ranging from benign infiltration to malignant lymphomas, often causing diffuse enlargement. Craniofacial abnormalities and craniosynostosis affects the development of the calvarium and facial bones which usually result in secondary changes of cranial fossae, skull base, and cranial vault and orbits. There may be other congenital developmental abnormalities associated. Tumor-like conditions of the craniofacial bones like Fibrous dysplasia FD [ 31 ] with extensive involvement of the maxilla, mandible, and skull base may lead to anatomic deformities of the orbit and encroachment of the neurovascular canals[ 1 ] [ Figure 37 ].

CT is the gold standard for imaging and 3D reformats are very useful in pre-operative assessment and post-surgical follow-up. A-C Craniofacial fibrous dysplasia with left proptosis. Computed tomography MPR images show expansion of diploic space with ground-glass appearance asterisk involving hemicraniofacial bones on left. Note obliteration of sinuses, encroachment of orbit with overcrowding of orbital contents. Multimodality approach for imaging of orbits helps in narrowing the differentials in establishing a confident radiologic diagnosis. CT is the modality of choice for bony detail and calcifications, whereas MR is superior for evaluation of the visual pathways, the globe and soft tissues.

We express our sincere gratitude to our esteemed colleagues and the faculty of the Department of Radiodiagnosis, INHS Asvini for their valuable contributions and constant support. Source of Support: Nil. Conflict of Interest: None declared. National Center for Biotechnology Information , U. Indian J Radiol Imaging.