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What our eyes see in the orbit and eye ball in the TC
emergency
Poster No.:
C-2605
Congress:
ECR 2015
Type:
Educational Exhibit
Authors:
J. C. Quintero Rivera, J. C. Castillo Iglesias, J. Alain Castillo, R. A.
Corral Rivadulla, P. Toranzo Ferreras, M. A. Trillo Lista; Ourense/
ES
Keywords:
Eyes, Trauma, CT, MR, Perception image, Foreign bodies,
Pathology
DOI:
10.1594/ecr2015/C-2605
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Learning objectives
Describe normally incidental radiographic findings in the eyeball and orbit.
Propose appropriate management of various diseases and incidental findings of
the eyeball and orbit.
Recognize important additional findings and potential pitfalls in the diagnosis of
orbital pathology.
Background
To date, MDCT has become a breakthrough for assessing the condition of the orbit,
allowing us to provide high resolution images, studies with contrast material at different
stages, bone assessment and multiplanar reconstructions and three dimensional.
Along with the above, the MDCT provides over other imaging techniques, the advantage
of its availability and the speed of acquisition of the study, constituting a basic diagnostic
tool in the screening of acute orbital pathology. In short, is the imaging modality of choice
for the study of urgent orbital pathology, providing sufficient information for recognition
and appreciation, especially calcifications and foreign bodies.
Findings and procedure details
ANATOMY OF THE ORBIT.
Bone walls of the orbit
The roof (superior wall) is formed primarily by the orbital plate frontal bone and also the
lesser wing of sphenoid near the apex of the orbit. The orbital surface presents medially
by trochlear fovea and laterally by lacrimal fossa. Fig. 1 on page 11
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The floor (inferior wall) is formed by the orbital surface of maxilla, the orbital surface of
zygomatic bone and the minute orbital process of palatine bone. Medially, near the orbital
margin, is located the groove for nasolacrimal duct. Near the middle of the floor, located
infraorbital groove, which leads to the infraorbital foramen? The floor is separated from
the lateral wall by inferior orbital fissure, which connects the orbit to pterygopalatine and
infratemporal fossa. Fig. 2 on page 11 )
The medial wall is formed primarily by the orbital plate of ethmoid, as well as contributions
from the frontal process of maxilla, the lacrimal bone, and a small part of the body of the
sphenoid. It is the thinnest wall of the orbit, evidenced by pneumatized ethmoidal cells.
Fig. 3 on page 12
The lateral wall is formed by the frontal process of zygomatic and more posteriorly by the
orbital plate of the greater wing of sphenoid. The bones meet at the zygomaticosphenoid
suture. The lateral wall is the thickest wall of the orbit, important because it is the most
exposed surface, highly vulnerable to blunt force trauma. Fig. 4 on page 13
Foramina and openings Fig. 5 on page 14
Optic canal
Superior orbital fissure
Inferior orbital fissure
Anterior ethmoidal foramen
Posterior ethmoidal foramen
Infraorbital foramen
Supraorbital foramen
Naso-lacrimal canal opening
Zygomatic orbital foramen
Contents Fig. 6 on page 15
Eye
Fascias: Orbital, Bulbar
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Extraocular muscles (Levator Palpebrae Superioris; Superior, Inferior, Lateral and Medial
Rectus muscles; Superior and Inferior oblique muscles)
Nerves: cranial nerves II, III, IV, V, and VI
Blood vessels
Extraocular Fat
Lacrimal gland, lacrimal sac, nasolacrimal duct
Eyelids
Medial palpebral ligament and lateral palpebral ligament
Medial and Lateral check ligaments
Suspensory ligament of the eyeball
Conjunctiv
Trochlea of superior oblique
Orbital septum
Ciliary ganglion and short ciliary nerves
Basic structure analysis through MDCT
First to identify the injury and structures involved:
Ocular: intraocular versus transscleral.
Optic nerve versus nerve sheath complex.
Intraconal space versus. conus versus. extraconal. Fig. 7 on page 16
Lacrimal gland: uni-or bilateral (systemic).
Solitary process versus. multispatial vs. transpatial.
Intracranial: process by direct extension versus. secondary.
Second to determine the characteristics of the image:
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Solid or cystic; heterogeneity.
Liquid density, fat, blood count or soft tissue.
Remodeling or bone destruction.
Well defined or infiltrative margins.
Enhancement.
INFECTIONS
Orbital infections account for more than half of the primary processes of orbital diseases.
Orbital location of infection with respect to the orbital septum is described either as
preseptal (periorbital) or postseptal (orbital).
Preseptal cellulitis
It is limited to soft tissue above the septum (preseptal fat, bulbar and tarsal conjunctiva,
eyelids and lacrimal apparatus).
Its spread is by neighborhood, infections in adjacent structures or local trauma.
Edema and swelling of the eye layers, chemosis and occasionally painful eye movement
is evident.
Important, NO PROPTOSIS.
Treatment is with oral antibiotics and observation.
Orbital cellulitis
It usually affects young patients or pediatric patients.
It is a consequence of contiguous spread of infectious processes, which in most cases
is based on the ethmoidal cells.
Generate significant inflammatory changes in the extraconal fat, effective mass and
PROPTOSIS.
They can form a subperiosteal abscess hypodense on CT with contrast.
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Treatment: intravenous antibiotics to prevent intracranial extension and abscess
formation.
Subperiostal abscess
The development of a subperiosteal orbital abscess is associated more commonly with
ethmoid sinusitis.
Dacryocystitis
Is a inflammation and dilation of the lacrimal sac, located along the inner edge.
Although the diagnosis of dacryocystitis is based on clinical manifestations, images may
be requested to exclude orbital cellulitis.
The finding of typical images is a well circumscribed lesion round which is centered in
the lacrimal fossa and showing enhanced periphery. Fig. 8 on page 17
Panophtalmitis and endophtalmitis
Acute suppurative infection of the eye after trauma or surgery.
Panophthalmitis may cause the rupture of the eyeball and blindness.
TRAUMATIC ORBITAL PATHOLOGY.
Proposal of systematic reading
Bone: rule out fractures.
Eyeball.
Rest of the intraorbital structures: fat, muscles, lacrimal gland, optic nerve and ophthalmic
vein.
Foreign bodies: radiopaque / transparent, location (intraocular, intra / extraconal) journey.
Associated fractures: Fig. 9 on page 18
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Massive Facial Fractures Lefort.
Skull fractures and intracranial complications.
Dislocation of the lens
Luxation posterior is the most common, identifying free lens in the posterior segment.
Fig. 10 on page 18
Posterior subluxation: The lens is anchored in one of its margins and angled towards the
rear portion.
Dislocation-anterior subluxation: It is less common since the iris prevents complete
dislocation.
Differential diagnosis: non-traumatic dislocation of the lens, typical of connective tissue
diseases (Marfan syndrome, Ehlers-Danlos syndrome, homocystinuria). Suspect where
BILATERAL.
Blow out eye
In blunt trauma, rupture is more common in the muscle insertions where the sclera is
thinner. Fig. 11 on page 19
CT findings without CIV: ocular volume loss, changes in eye contour: sign of "flat tire",
discontinuities in the sclera, intraocular air, and foreign bodies.
Ocular evisceration
An evisceration is the removal of the eye`s contents, leaving the scleral shell and
extraocular muscles intact. The procedure is usually performed to reduce pain or improve
cosmetic in a blind eye, as in cases of endophthalmitis unresponsive to antibiotics. An
ocular prosthetic can be fitted over the eviscerated eye in order to improve cosmetic. Fig.
12 on page 20 ).
Foreign bodies
The MDCT is the imaging method of choice because of its high sensitivity. Fig. 13 on
page 21
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In the metal < 1mm foreign bodies. We must consider the differential diagnosis with
postoperative material.
In non-metallic foreign bodies, the diagnosis is more problematic, depending on the size
and density.
RETINAL DETACHMENT
Is a separation of sensory retina from the retinal pigment epithelium (subretinal space).
Vitreous step the subretinal space, acquiring typical "V" to retain the front and rear (vertex
on the optical disk) fasteners. Fig. 14 on page 22
Causes: Diabetic retinopathy, trauma, magna myopia, congenital cataract, congenital
glaucoma, surgery, sickle cell anemia, leukemia, SLE and metastasis.
INCIDENTAL FINDINGS (POTENTIAL ¨PITFALLS¨).
Postsurgical and posttreatment changes Fig. 15 on page 23
Ocular prosthesis.
Aphakia / intraocular lenses.
Metal / sealed with silicone for the treatment of retinal detachment bands.
Pneumatic retinopexy.
Enucleation.
Subperiosteal hematoma ttº anticoagulant.
Refractive errors
Increased ocular anterior-posterior diameter: myopia.
Increased cross-eye diameter: hyperopia. Fig. 16 on page 24
Degenerative changes
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Drusen: calcifications in the optic nerve.
Nonspecific calcifications in the insertions of the rectus muscles.
Calcifications in the trochlea of Obl.superior muscle.
Calcifications in the optic nerve.
Phthisis bulbi: atrophic eye, withdrawn, with dystrophic calcifications secondary to
trauma, surgery or infection. Fig. 17 on page 25
Cataract.
ORBITAL TUMORS/BONE WALLS.
Lymphoma
Location possible anywhere in orbit, having a primary or systemic origin
It is characteristic of the elderly, and periorbital edema presents with painless evolution
of latent and mild exophthalmos.
In imaging studies orbital lymphoma is a diffuse infiltrative mass, which can infiltrate the
extrinsic muscles or the lacrimal apparatus. Fig. 18 on page 26
Its main DD is inflammatory pseudotumor, being often impossible the distinction between
these two entities.
Meningioma sellar /orbital
The Meningiomas typically manifest CT as homogeneous, extra-axial lesions with
well-defined margins and usually hyperdense relative to the adjacent parenchyma on
unenhanced images. Fig. 19 on page 28
Usually present calcifications, which can be nodular, punctate or dense.
After administration of intravenous contrast, a marked and generally homogeneous
enhancement of broad base, which has been described as "dural tail" is shown.
This last sign is not specific to meningiomas, but can be identified in 65% of cases related
to thickening of the dura mater, reactive or neoplastic infiltration.
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INFLAMMATORY DISORDERS
Thyroid eye disease
In thyroid eye disease classically observed enlargement of the extraocular muscles,
sparing the tendon insertion. Fig. 20 on page 29
The inferior, medial, superior and lateral rectus muscles (listed in descending order of
frequency of involvement), may be involved.
Muscle thickness:
Medial rectus: 4.1 +/- 0.5mm.
Lateral rectus: 2.9 +/- 0.6mm.
Superior rectus: 3.8 +/- 0.7mm.
Inferior rectus: 4.9 +/- 0.8 mm.
Superior Oblique: 2.4 +/- 0.4mm.
VASCULAR MALFORMATIONS.
Orbital varices
Orbital varices, the most common cause of spontaneous orbital haemorrhage, are
congenital venous malformations with slow flow, characterized by the proliferation of
venous elements and massive dilation of one or more orbital veins.
The vast majority of orbital varices have great communication with the venous system,
resulting in distention of the veins and increasing proptosis during the Valsalva maneuver
or postural change.
The orbital varices that have small communication with the venous system are prone to
thrombosis and bleeding.
The imaging findings of orbital varices can be subtle and studies may be required during
Valsalva maneuvers for the characteristic appearance.
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The lesions are intensely enhanced after administration of contrast material. Fig. 21 on
page 29
Images for this section:
Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig. 5
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Fig. 6
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Fig. 7
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Fig. 8: Bilateral dacryocystitis
Fig. 9: Lefort fractures clasification
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Fig. 10: The lens is anchored in one of its margins and angled towards the rear portion
(posterior dislocation)
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Fig. 11: Blunt eye trauma
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Fig. 12: Ocular evisceration
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Fig. 13: Ocular metallic foreign bodie
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Fig. 14: Retinal detachment
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Fig. 15: Postsurgical changes
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Fig. 16: Hyperopia
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Fig. 17: Atrophic eye, withdrawn, with dystrophic calcifications secondary to trauma,
surgery or infection
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Fig. 18: Lymphoma
Fig. 19: Orbitary meningioma
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Fig. 20: Enlargement of the extraocular muscles, sparing the tendon insertion
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Fig. 21: Orbital varices
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Conclusion
Knowledge of the characteristics images of the various conditions and diseases
that may occur in urgent MDCT studies are necessary for rapid and accurate
diagnosis.
The ability to distinguish these important benign lesions, such as calcifications,
therapeutic devices, postsurgical changes, etc., allows an optimal management of
diagnosis, avoid additional tests and unnecessary follow.
Personal information
Juan Carlos Quintero Rivera
Complexo Hospitalario Universitario de Ourense (CHUO)
Radiology Department
Chief of department: Manuel Angel Trillo Lista
Spain
e-mail: [email protected]
References
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Naik M, Tourani K, Sekar Ch, and Honavar S. Interpretarion of computed tomography
imaging of the eye and orbit. A systematic approahc. Ophtalmology practice 2002;
50:339-353
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Tawfik H, Abdelhalim A, and Elkafrawy M. Computed tomography of the orbit. A review
and an update. Saudi Journal of Ophtalmology 2012; 26:409-418
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