51THE ORBIT

DAVID SUTTON 51.54

DAVID SUTTON PICTURES

DR. Muhammad Bin Zulfiqar PGR-FCPS III SIMS/SHL

• Fig. 51.1 Optic nerve glioma. Right (A) and left (B) optic canal views show a large right canal, confirming extension of the tumour to this portion of the nerve.

• Fig. 51.2 (A) Left common canaliculus block (proximal end). Normal right side for comparison. (B) Subtraction macrodacryocystogram showing a lacrimal sac mucocele. (C) General dilatation of the lacrimal sac and duct due to an incomplete obstruction at the lower ostium (arrow).

• Fig. 51.3 Inferior and medial blow-out fractures. Coronal CT image demonstrates inferomedial displacement of bony fragments of left orbital floor (arrow) as well as accompanying fracture of left lamina papyracea (arrowhead). (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.4 Medial blow-out fracture. Axial (A) and coronal (B) CT images demonstrate partial herniation of medial rectus muscle and orbital fat into left ethmoid air cells through fractured lamina papyracea (arrow). There is associated intraorbital emphysema (asterisk).

• Fig. 51.5 Ruptured globe. Opacification of ethmoids with blood and fluid secondary to extensive comminuted nasal and ethmoid fractures. Bilateral fractures of lateral orbital wall (arrows). Hyperdense blood fills ruptured and misshapen left globe. There is contusion of retro-orbital fat as well as preseptal soft-tissue swelling.

• Fig. 51.6 Dislocated lens. Axial T 2 - weighted MR image demonstrates dislocated right lens dependently within the vitreous chamber. Dislocation is also seen on axial non-contrast CT.

• Fig. 51.7 Vitreous haemorrhage. Axial T,- (A) and T 2- weighted (B) MR images demonstrate layering of blood within the dependent portion of the right globe. High signal on T 1 -weighted image and low signal on T2- weighted image represents haemorrhage.

• Fig. 51.8 Retro-orbital haemorrhage. Axial (A) and coronal (B) CT images demonstrate hyperdense lesion adjacent to left optic nerve. There is proptosis due to infiltration of the retro-orbital fat.

• Fig. 51.10 Trauma with blow-out fracture and choroidal detachment. Axial CT image (A) demonstrates preseptal soft-tissue swelling as well as infiltration of retro-orbital fat representing contusion. Elevation of choroid (arrowheads) is due to hyperdense suprachoroidal haemorrhage. Opacification of left ethmoid sinuses is related to medial blow-out fracture. Axial T1 -weighted MR (B) confirms presence of suprachoroidal blood.

• Fig. 51.11 Intraorbital wooden foreign body. Axial CT image (A) performed immediately after injury demonstrates large radiolucent splinter penetrating left globe, simulating appearance of intraorbital emphysema. Follow-up examination (B) performed 3 weeks later demonstrates increased density of foreign body as the interstices have become filled with fluid.

• Fig. 51.12 Intraorbital metallic foreign body. Fractured tip of knife blade demonstrated on lateral plain film (A) is well localised to left intraconal compartment by axial (B) and coronal (C) CT images. Retro-orbital haematoma obliterates the normal intraconal fat. There is rupture of the globe. (Case courtesy of Orlando

• Fig. 51.12 Intraorbital metallic foreign body. Fractured tip of knife blade demonstrated on lateral plain film (A) is well localised to left intraconal compartment by axial (B) and coronal (C) CT images. Retro-orbital haematoma obliterates the normal intraconal fat. There is rupture of the globe. (Case courtesy of Orlando

• Fig. 51.13 Displaced metallic orbital floor prosthesis. Lateral scout radiograph (A) demonstrates operative fixation of previous mandible fracture and orbitonasal injuries. Punctate densities represent projectiles from recent shotgun blast. Axial CT image (B) demonstrates upward displacement of metallic orbital floor prosthesis (arrow).

• Fig. 51.14 Extraconal orbital abscess from sinusitis. Enhanced axial CT image demonstrates opacification of ethmoid sinuses and mucosal thickening within the sphenoid sinus. There is preseptal cellulitis on the left, with thickening of the eyelid. Low-attenuation subperiosteal abscess in the medial extraconal compartment causes proptosis.

• Fig. 51.15 Scleral pseudotumour. Marked thickening and irregularity of the sclera of the right globe involves the adjacent retro-orbital fat.

• Fig. 51.16 Diffuse pseudotumour. Axial MR T,-weighted image showing a diffuse mass in the right orbit due to pseudotumour.

• Fig. 51.17 Myositic pseudotumour. Enhanced axial (A) and coronal (B) CT images demonstrate fusiform enlargement of right lateral rectus muscle (arrowheads).

• Fig. 51.18 Thyroid ophthalmopathy. Unenhanced axial (A) and coronal (B) CT images demonstrate massive enlargement of the rectus muscles, including fusiform enlargement of the lateral rectus with relative sparing of the distal muscle insertion.

• Fig. 51.19 Rhabdomyosarcoma. Contrast-enhanced axial CT image (A) through orbits demonstrates right proptosis due to large, lobular, intraorbital mass. Image at lower level (B) demonstrates invasion of right maxillary sinus (asterisk) as well as extension through lateral orbital wall (arrow), consistent with the aggressive nature of this tumour. (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.21 Lymphoma. Enhanced axial CT image demonstrates extension of right orbital apex mass to the right cavernous sinus (arrow) via this superior orbital fissure. There is right proptosis. Enlargement and abnormal enhancement of right medial and lateral rectus muscles could represent infiltration by tumour, but are more likely due to venous congestion from cavernous sinus obstruction. (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.20 Lymphoma. T,-weighted MR image (A) demonstrates proptosis of right globe due to a large intermediate signal intensity lesion that involves the lacrimal fossa and the right lateral rectus muscle (arrow), with extension posteriorly in the extraconal compartment. Postcontrast image (B) demonstrates homogeneous enhancement.

• Fig. 51.22 Cavernous sinus thrombosis. Axial CT image (A) demonstrates proptosis with preseptal soft-tissue swelling and enlargement of the left lateral rectus muscle (arrowhead). There is subtle enlargement of the left cavernous sinus, with areas of diminished enhancement. Image at a higher level (B) demonstrates massive distension of the left superior ophthalmic vein (arrow).

• Fig. 51.23 Cavernous haemangioma. T,-weighted axial (A) and sagittal (B) MR images demonstrate proptosis of right globe due to well circumscribed, mid to high signal intensity intraconal mass.

• Fig. 51.24 Lymphangioma. Supine axial (A) and prone coronal (B) enhanced CT images demonstrate a complex intraorbital mass medial to the right globe. Fluid-fluid level is characteristic for haemorrhage, and consistent with the clinical history of acute proptosis and ocular pain. (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.25 Lymphangioma. Axial T,-weighted (A) and T2 –weighted (B) MR images demonstrate mild right proptosis due to complex, multiloculated, cystic, extra-axial lesion in the superomedial aspect of the right orbit.

• Fig. 51.26 Haemangiopericytoma. Axial CT image (A) demonstrate! well-circumscribed enhancing retro-orbital lesion. Bone window, (B) demonstrate erosion of adjacent lateral orbital wall.

• Fig. 51.27 Encephalocele. Axial T,-weighted MR image demonstrates marked proptosis of right globe with stretching of attenuated right optic nerve (arrowhead) due to herniation of dura and temporal lobe through a large sphenoid defect in this patient with neurofibromatosis.

• Fig. 51.28 Neurinoma. Contrast-enhanced CT demonstrates medial displacement of right optic nerve by a well-circumscribed, homogeneously enhancing Vlth nerve neurinoma. Note adjacent scalloping of sphenoid bone (arrow).

• Fig. 51.29 Plexiform neurofibroma. T,-weighted (A) and T2 - weighted (B) MR images demonstrate extensive left temporal scalp lesion with extension to the left orbit resulting in mild proptosis. MR also demonstrates ectatic left optic nerve (arrow). CT image at bone windows (C) demonstrates associated bony defect of left lambdoid suture.

• Fig. 51.29 Plexiform neurofibroma. T,-weighted (A) and T2 - weighted (B) MR images demonstrate extensive left temporal scalp lesion with extension to the left orbit resulting in mild proptosis. MR also demonstrates ectatic left optic nerve (arrow). CT image at bone windows (C) demonstrates associated bony defect of left lambdoid suture.

• Fig. 51.30 Leukaemic chloroma. Enhanced axial CT image in 12-year-old female with ALL demonstrates left proptosis due to well-circumscribed, homogeneous extraconal mass. (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.31 Metastatic prostate carcinoma. Axial CT image (A) through orbits demonstrates small lytic lesion of left lateral orbital wall in a patient with prostate carcinoma. Soft-tissue windows (B) demonstrate contiguous extension of soft tissue into lateral extraconal compartment (asterisk) with medial displacement of the lateral rectus muscle.

• Fig. 51.32 Lymphoma. Bilateral, symmetric, enhancing soft-tissue masses occupy the lacrimal gland fossa. There is posterior extension in the extraconal compartment with bilateral proptosis.

• Fig. 51.33 Histiocytosis. Axial CT image (A) demonstrates soft-tissue mass in superolateral aspect of left orbit. Bone window (B) shows associated bony erosion.

• Fig. 51.34 Lacrimal gland dermoid. Coronal (A) and axial (B) T 1 –weighted images demonstrate a well-circumscribed lesion located in the upper outer quadrant of left orbit. High signal intensity is consistent with fat.

• Fig. 51.35 Varix. Contrast-enhanced CT demonstrates fluid-contrast level within preseptal varix of left orbit.

• Fig. 51.36 Carotid-cavernous fistula. Enhanced axial CT image (A) demonstrates enlargement or right superior ophthalmic vein (arrow). Image at lower level (B) demonstrates engorgement of right medial rectus muscle as well as elevation of choroid (arrowhead) by suprachoroidal effusion resulting from orbital venous hypertension.

• Fig. 51.37 Carotid-cavernous fistula. Right internal carotid injection (straight arrow), lateral view, opacities cavernous sinus (curved arrow) as well as dilated superior ophthalmic vein (arrowhead). Note absence of filling of intracranial carotid circulation.

• Fig. 51.38 Optic nerve glioma. Enhanced coronal CT image demonstrates homogeneous enhancement of enlarged right optic nerve.

• Fig. 51.39 Optic nerve glioma. Enhanced fat-saturated axial T,-weighted image (A) demonstrates mild enhancement and enlargement of intraorbital and canalicular segments of left optic nerve as well as dilated low signal intensity perioptic space. Coronal image (B) confirms enlargement of nerve and surrounding perioptic space.

• Fig. 51.40 Optic nerve meningioma. Enhancement of thickened right optic nerve with elevation of optic disc (arrowhead).

• Fig. 51.41 Optic nerve meningioma. Coronal T,-weighted MR image (A) demonstrates marked thickening of right optic nerve sheath (arrowhead). Axial T,-weighted postcontrast fat-saturated image (B) demonstrates peripheral enhancement of the thickened right optic nerve sheath. Nonenhancing soft tissue within represents the encased optic nerve.

• Fig. 51.42 Pseudotumour cerebri. Enhanced, fat-saturated axial T1 -weighted (A) and T 2-weighted (B) MR images demonstrate dilated optic nerve sheath surrounding optic nerves (arrowheads). Papilloedema (seen on right in (B) and fluid-filled empty sella (asterisk) are frequent accompanying findings.

• Fig. 51.43 Optic neuritis. Contrast-enhanced T,-weighted coronal (A) and fat-saturated axial T, (B) MR images demonstrate subtle enlargement and enhancement of the left optic nerve (curved arrow). T 2 -weighted axial image (C) demonstrates corresponding increased signal intensity (straight arrow).

• Fig. 51.43 Optic neuritis. Contrast-enhanced T,-weighted coronal (A) and fat-saturated axial T, (B) MR images demonstrate subtle enlargement and enhancement of the left optic nerve (curved arrow). T 2 -weighted axial image (C) demonstrates corresponding increased signal intensity (straight arrow).

• Fig. 51.44 Optic neuritis. Axial T,-weighted postcontrast MR image with fat saturation demonstrates enhancement of the intraconal portion of the right optic nerve. Normal left optic nerve is indistinguishable from surrounding intraconal fat. Note normal bright enhancement of extraconal muscles.

• Fig. 51.45 Optic neuritis. Straightening and thickening of right optic nerve. Similar but less severe changes on left.

• Fig. 51.46 Sarcoidosis. Axial T 1 - weighted MR image (A) demonstrates thickening of optic nerves and chiasm (asterisk). Fat-saturated contrast enhanced axial (B) and coronal T 1 - weighted enhanced (C) images demonstrate marked enhancement of the optic nerves and chiasm.

• Fig. 51.46 Sarcoidosis. Axial T 1 - weighted MR image (A) demonstrates thickening of optic nerves and chiasm (asterisk). Fat-saturated contrast enhanced axial (B) and coronal T 1 - weighted enhanced (C) images demonstrate marked enhancement of the optic nerves and chiasm.

• Fig. 51.47 Coloboma. Axial CT image demonstrates bilateral retinal defects with outpouching in the region of the optic nerve head.

• Fig. 51.48 Congenital absence of the lens. Axial T,- (A) and T2 –weighted (B) MR images demonstrate bilaterally misshapen globes, with microphthalmous , on left. Lens is not visualised. Presence of the ciliary mechanism (arrow) differentiates congenital absence of the lens from ocular cyst in this case.

• Fig. 51.49 Phthisis bulbi. CT image showing calcification of shrunken and irregularly thickened left globe.

• Fig. 51.50 Retrolental fibroplasia. Left globe is enlarged; there is right microphthalmous with abnormally increased attenuation throughout the posterior vitreous chamber.

• Fig. 51.51 Choroidal melanoma. Contrast-enhanced coronal CT image demonstrates enhancing lesion of the medial retina of the left eye with transscleral invasion (arrow). (Case courtesy of Orlando Ortiz, M.D.)

• Fig. 51.52 Choroidal melanoma. T,- (A) and T2 -weighted (B) MR images demonstrate well-circumscribed broad based lesion of posterior left retina. High signal intensity on T,-weighted images and low signal intensity on T,-weighted images is due to characteristic paramagnetic effect of melanin.

Fig. 51.53 Retinoblastoma. Non-contrast axial CT (A) demonstrates punctate foci of calcification within hyperdense left globe. Axial T,-weighted (B) and T2 -weighted (C) MR images demonstrate full extent of large lesion within left globe. High signal intensity on T,-weighted images, and low signal intensity on T2 -weighted images is consistent with the dense cellular nature of this tumour.

• Fig. 51.54 Retinoblastoma. Non-contrast axial CT (A) demonstrates bilateral partially calcified intraocular masses. Enhanced image (B) demonstrates spread through sclera and into intraconal compartment (arrow), predicting poor prognosis.

• Fig. 51.55 Trilateral retinoblastoma. Enhanced axial CT image (A) demonstrates large lobular calcification based on right retina. A second, smaller, retinal lesion can be seen overlying the left optic nerve head. Axial image at higher level (B) demonstrates hydrocephalus due to large enhancing mass in the region of the posterior third ventricle/pineal cistern representing pineoblastoma.

• Fig. 51.56 Coats' disease. Contrast-enhanced CT demonstrates hyperdensity. in posterior portion of left globe.

• Fig. 51.57 Persistent hyperplastic primary vitreous. Non-contrast axial CT demonstrates hyperdensity throughout the posterior compartment of the right eve.

• Fig. 51.58 Persistent hyperplastic primary vitreous. Axial CT (A) demonstrates central linear density within smaller right globe. Sagittal T,-weighted MR (B) confirms findings of PHPV.

• Fig. 51.59 Drusen. CT shows bilateral punctate calcifications, located centrally over the optic nerve head.

• Fig. 51.60 (A,B) Ocular prosthesis. Axial T 1 -weighted images demonstrate left ocular prostheses in two different patients.

• Fig. 51.61 Lacrimal gland cyst. Axial CT image demonstrates nonenhancing cystic lesion lateral to the globe in upper outer quadrant of left orbit.

• Fig. 51.62 Adenoid cystic carcinoma. Axial T,-weighted (A) and T2-weighted fat-saturated (B) MR i mages demonstrate enlargement of the posterior lobe of the left lacrimal gland by heterogeneously enhancing lesion. Note adjacent remodelling of sphenoid bone, indicating longstanding presence of lesion.

• Fig. 51.63 Sarcoidosis. Axial (A) and coronal (B) T,-weighted images demonstrate prominent bilateral enhancement of lacrimal glands (arrows).

• Fig. 51.64 Squamous-cell carcinoma of lacrimal sac. Axial (A) and coronal (B) CT scans demonstrate a large enhancing mass in the inferomedial portion of the left orbit. There is proptosis and lateral deviation of the left globe. Bone windows (C) demonstrate destruction of medial orbital wall and nasolacrimal duct canal. Normal bony canal is seen on right (arrow).

• Fig. 51.64 Squamous-cell carcinoma of lacrimal sac. Axial (A) and coronal (B) CT scans demonstrate a large enhancing mass in the inferomedial portion of the left orbit. There is proptosis and lateral deviation of the left globe. Bone windows (C) demonstrate destruction of medial orbital wall and nasolacrimal duct canal. Normal bony canal is seen on right (arrow).

• Fig. 51.65 Nasolacrimal lymphoma. Enhanced axial (A) and coronal (B) CT images demonstrate right ethmoid mass extending to the lacrimal sac in the region of the right medial canthus. Non-enhanced coronal T1 –weighted MR image (C) shows extensive involvement of right ethmoids and right nasal cavity; axial T 2 -weighted MR image (D) shows abnormal increased signal in right anterior ethmoid region.

• Fig. 51.65 Nasolacrimal lymphoma. Enhanced axial (A) and coronal (B) CT images demonstrate right ethmoid mass extending to the lacrimal sac in the region of the right medial canthus. Non-enhanced coronal T1 –weighted MR image (C) shows extensive involvement of right ethmoids and right nasal cavity; axial T 2 -weighted MR image (D) shows abnormal increased signal in right anterior ethmoid region.