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Look at Me Now! A Case
Based Review of Common
Emergent Orbital
Pathologies
Asha Bhatt, MD, PGY 5
Parul Patel, MD, Attending Radiologist
Rochester Radiology Associates
ASNR 2016
eEdE-123
Control#:1947
No Disclosures
Purpose
•
Review normal orbital anatomy using both computed tomography (CT) and
magnetic resonance (MR).
•
Case based review of common emergent pathologies of the orbits and
globes divided into two major categories:
– Trauma
• Globe
• Fractures
• Hemorrhage
– Infection
Anatomy
•
The orbital septum, typically not visualized, is a membranous structure which extends
from the orbital rim to the eyelids and serves as the anterior boundary of the orbit.
•
The globe is subdivided into anterior and posterior segments by the lens.
•
The extra-ocular muscles within the orbit form a “muscle-cone” to create three spaces
– Conal space or cone: Comprised of the extra ocular muscles and fascia
– Extraconal space: Comprised of fat and lacrimal gland (arrow)
– Intraconal space: Comprised of fat, cranial nerve II, superior ophthalmic vein, ophthalmic
artery
Anatomy
Coronal noncontrast CT demonstrates extraconal air (yellow arrow) within the
right orbit above the level of the superior rectus muscle.
Axial CT, on lung windows, the orbital septum (red arrows) is easily delineated
between the intraorbital (extra-conal) air anterior to the globe and periorbital soft
tissue emphysema.
Anatomy
Levator Palpebrae Superioris
Superior Rectus
Superior Ophthalmic Vein
Lateral Rectus
Muscle
Superior
Oblique
Muscle
Medial Rectus
Muscle
Globe
Inferior
Ophthalmic Vein
Inferior Rectus Muscle
Anatomy
Posterior Segment
Lens
Aqueous
Fluid
Superior Rectus Vitreous Fluid
Muscle
Anterior
Segment
Optic Nerve
Inferior Rectus
Muscle
MR Signal Characteristics of
Major Orbital Structures
Structure
T1
T2
Aqueous fluid,
Vitreous fluid and
CSF
Hypointense
Hyperintense
Lens
Hyperintense to vitreous
Hypointense to
vitreous
Scelera, choroid and
retina
Intermediate signal
Hypointense
Extraocular muscles
- Intermediate signal
- Enhance with contrast
Intermediate signal
Optic nerve
- Isointense to cerebral
white matter
- Normal optic nerve does
not enhance with contrast
Isointense to
cerebral white
matter
Orbital fat
Hyperintense
Intermediate
Lacrimal gland
Intermediate signal similar
to grey matter
Intermediate signal
similar to grey
matter
T2
T1
CT versus MRI in the Evaluation
of Orbital Pathologies
• CT
– Superior in delineation of calcifications within
lesions/masses
– Superior to evaluate bony erosions, and orbital fractures
– Modality of choice for evaluation of metallic foreign bodies
• MRI
– Exquisite contrast resolution makes MR superior to CT in
the evaluation of soft tissues structures
– Signal abnormalities in the optic nerves, muscles and
other soft tissues allows the radiologist to pick up
pathology on MRI that would be occult on CT
Globe Trauma
Diagnosis
Features
CT
MRI
Retinal
detachment
- Accumulation of blood or fluid in the subretinal space between two layers of retina
- Configuration of collection is typically
crescent or “V” shaped with apex at the
optic disc
“V” shaped hyperdense abnormality
in the globe
T1 “V” shaped hyperintense and T2 “V”
shaped isointense (to normal vitreous
body) abnormality in the globe
Choroidal
detachment
- Accumulation of blood or fluid in between
choroid and sclera
- Configuration of abnormality is lentiform
shaped along the medial and lateral walls
of globe
Lenitform shaped hyperdense
abnormality in the globe
Leniform shaped T1 hyperintense and T2
isointense (to normal vitreous body)
abnormality in the globe
Lens
Dislocation
- Subluxation or dislocation of the lens
from its normal position secondary to
dysfunction or disruption of zonular fibers
Lens displaced from its normal
location and typically seen in the
posterior chamber
Lens displaced from its normal location
and typically seen in the posterior
chamber
Globe Rupture
- Disruption of the outer membranes of the
globe by blunt or penetrating trauma
Globe deformity or wall irregularity,
destruction or dislocation of the
lens, intraocular hemorrhage,
intraocular foreign body, shallow
AC, and intraocular gas
-Not the study of choice to initially
evaluate globe rupture due to possible
metallic foreign bodies (contraindication),
time constraints, not widely accessible,
and poor definition of osseous structures
Foreign Body
(FB)
- Associated with orbital fractures and
globe injury
- Unlike metallic foreign bodies, organic
foreign bodies like wood are porous and
provide a good medium for microbial
agents which can result in cellulitis and
abscess
- CT demonstrates most foreign
bodies
- CT is safe for the evaluation for
metallic foreign bodies
- Metallic foreign bodies however
result in beam-hardening artifact
limiting evaluation of the globe and
adjacent structures at times
- May fail to detect organic foreign
bodies like wood
- T1 post contrast demonstrates
enhancement of inflammatory tissue
around organic foreign bodies
- STIR demonstrates increased signal
due to inflammatory response around an
organic foreign bodies
- Gradient Echo (GRE) demonstrates
susceptibility artifact
Lens Dislocation- Native Lens
There is a thin high density
curvilinear object in the posterior
chamber corresponding to a
dislocated right lens (red arrows).
Note the normal position of the left
lens (yellow arrow).
Lens Dislocation- Prosthetic
Lens
There is a thin high density
curvilinear object in the posterior
chamber of the right globe
corresponding to a dislocated
prosthetic right lens (red arrows).
Note the normal position of the left
prosthetic lens (yellow arrow).
Globe Rupture
There is irregularity of the left globe, with loss of the normal spherical shape
compatible with contained rupture. The lens is absent (red oval) and there is free
communication between the anterior and posterior segments (yellow arrow).
There is a curvilinear hyperdensity at the posterior aspect of the globe which may
represent blood products and/or the dislocated lens (blue arrow).
Globe Rupture
There is abnormal morphology (yellow arrow) and appearance of the left globe.
There is high density material replacing the normal hypodense fluid in the posterior
chamber (red arrow) along with significant left periorbital soft tissue edema.
Ophthalmology Exam- Total hyphema (blood within the anterior chamber), and a
hypotenous, shallow appearing anterior chamber
Patient underwent surgical repair for globe rupture.
Traumatic Iritis
There is a small amount of hyperdense material located inferior to the left
ocular lens (red arrow). This was felt to represent a small amount of vitreous
hemorrhage given the history of left eye pain after assault.
Ophthalmology evaluation demonstrated traumatic iritis (inflammation of the
uvea, iris, or both).
Foreign Body
There is an 2.4 cm metallic foreign body within the
anterior aspect of the left orbit (red arrow). There is
hyperdense material within the posterior aspect of the
left globe suggestive of hemorrhage (yellow arrow).
Vitreous Hemorrhage
There is an elliptical peripherally based hyperdensity at the posterior
aspect of the right globe (red arrow). Differential diagnosis includes
hemorrhage, retinal detachment or neoplasm.
Ophthalmology Exam- Likely vitreous hemorrhage but unable to rule
out retinal detachment.
Full Thickness Scleral
Laceration
The right globe has an irregular contour (yellow arrow) with increased soft tissue
density circumferentially about the central aspect of the globe (red arrow). Initial
report suggested possible contained globe rupture given the history of fall and
subsequent pain, redness, and blurriness in the right eye.
Surgical evaluation demonstrated no rupture, but a circumferential full thickness
scleral laceration.
Retinal Detachment
T2
There are V-shaped thin T2 hypointense lines arising from the optic disc
and extending anteriorly towards the ciliary bodies in the left globe.
Findings are consistent with retinal detachment (yellow arrow).
Trauma: Fractures
Diagnosis
Blow out
fracture
Features
CT
- Due to an increase in intraorbital pressure which forces
the intra-orbital fat inferiorly
through the roof of the maxillary
sinus.
- Entrapment is a clinical, not
radiographic diagnosis
- Simple or comminuted fracture of
orbital floor/medial wall
- May have herniation of orbital contents
such as fat and extraocular muscles
- May have associated injury to the
orbital soft tissues such as globe rupture
or retrobulbar hematoma
MRI
- Not the study of choice to
evaluate orbital fractures
Superior Wall Fracture
There is a fracture of the superior wall of the right orbit (red arrow) extending into
the extra-conal fat. Linear fracture fragment is located immediately adjacent to the
superior aspect of the right orbit (yellow arrow).
Inferior Orbital Wall Fracture
There is a comminuted displaced fracture of the right inferior orbital wall with
herniation of intraorbital fat into the maxillary sinus (red arrows). There is no
herniation of extraocular muscles. The inferior rectus muscle is in its normal
location (red oval). There is extratraconal air (purple arrow), as well as right
periorbital soft tissue emphysema and edema (yellow arrow). There is high
density layering fluid within the right maxillary sinus, consistent with
hemosinus (blue arrow).
Medial Orbital Wall Fracture
There is a medially displaced right medial orbital wall (lamina papyracea)
fracture with medial herniation of intraorbital fat (red arrow) and the medial
rectus muscle. The medial rectus muscle is slightly thickened and medially
displaced (yellow arrow). There are multiple tiny foci of intraconal and
extraconal air (purple arrow). Clinical correlation for entrapment should be
considered.
Medial Orbital Wall Fracture
There is a fracture of the medial wall (lamina papyracea) of the left orbit with
medial herniation of the intraorbital fat and medial rectus muscle into the left
ethmoid air cells (blue arrow) The left medial rectus muscle is enlarged and shows
mild hyperdensity, likely related to hemorrhage and edema (red arrow). Clinical
correlation for entrapment should be considered. There is high density
material/stranding within the intra-conal fat (yellow arrow) suggestive of
hemorrhage.
Fractures Continued
There are left lamina papyracea and inferior orbital wall fractures with inferior herniation
of extraconal fat (blue arrow). Additionally, there is medial bowing of the medial rectus
muscle suggesting muscle entrapment (red arrow). Clinical correlation for entrapment
should be considered. There is associated traumatic hemosinus (yellow arrow).
Acute-Orbital Blowout Fracture
STIR
T1
T1 FS +C
There is a right orbital blowout fracture involving the floor of the orbit with herniation of
intraorbital fat (yellow arrow) into the right maxillary sinus with elongation of the right
inferior rectus muscle (red arrow) that extends across the fracture. There is complex
fluid within the right maxillary sinus, likely hemorrhagic (blue arrow). There is mild
edema and corresponding enhancement surrounding the right optic nerve sheath, likely
related to posttraumatic edema (purple arrows).
The left globe is within normal limits. Left extra ocular muscles show normal size and
configuration with normal homogeneous enhancement on the postcontrast images. Left
optic nerve shows normal signal characteristics.
Chronic Orbital Floor Fracture
Coronal T2
There is deformity of the left orbital floor with herniation of orbital fat (red
arrow). Note the lack of edema and blood products in this case, as findings
are related to a remote prior injury. There is mild polypoid mucosal thickening
identified within both maxillary sinuses (blue arrows).
Chronic Orbital Floor Fracture
T1 FS +C
T2
There is a left orbital floor fracture with herniation of the orbital fat into the
left maxillary sinus (red arrow). The inferior rectus muscle is slightly inferior
in location when compared to the right side, however, without evidence for
entrapment (yellow arrow).
Trauma: Miscellaneous
Diagnosis
Features
CT
Carotid-Cavernous
fistula
- May be traumatic (direct, high flow)
or atraumatic/spontaneous (indirect,
low flow)
- Clinical symptoms: bruit, pulsating
exophthalmos, orbital
edema/erythema, decreased vision,
glaucoma, headache
- Dilated superior ophthalmic
vein (SOV) and ipsilateral
cavernous sinus (CS)
- Increased enhancement of
EOMs and small orbital vessels
Retrobulbar
hemorrhage
- Due to rupture of infraorbital
artery/branches following trauma or
surgery
- Irregular soft tissue mass
involving posterior globe surface
and distal portion of the
intraorbital portion of optic nerve
MRI
- T1-Dilated SOV and CS with
asymmetric enhancement
- May see tortuous collaterals
with cerebral drainage
- T2-Flow void in enlarged
SOV & cavernous sinus
Carotid-Cavernous Fistula
The right extraocular muscles are enlarged with assoicated proptosis and edema in
and around the right orbit. There is asymmetric enlargement of the right superior
ophthalmic vein (yellow arrows) and the right cavernous sinus. There is abnormal
enhancement within the right cavernous sinus (red arrow) in the arterial phase.
Findings are consistent with a right carotid-cavernous fistula.
Hemorrhage
Axial unenhanced CT images of the brain at the level of the orbits demonstrate
extraconal (red arrow) and intraconal (yellow arrows) hemorrhage within the left
orbit with moderate left proptosis. There is no evidence of a lens dislocation. There
is a fracture of left lamina papyracea with medial herniation of intraorbital contents
(blue arrow).
Soft Tissue Hematoma
There is a large right periorbital soft tissue hematoma (red arrow).
The globes are intact. There is no intraconal hemorrhage.
Infection
Disease
Location
Complications
CT
T1
T2
Pre-septal Orbital
Cellulitis
Disease limited to
periorbital soft tissues,
anterior to orbital
septum
Post-septal cellulitis
Infiltration of
periorbital fat
- Hypointense
infiltration of normal
fat
- Diffuse
heterogeneous
enhancement
Heterogeneous
hyperintensity
Post-septal Orbital
Cellulitis
Disease involving the
structures posterior to
the orbital septum:
- Intraconal
- Extraconal
- Periosteum
Abscess, empyema,
cerebritis, subdural
or epidural effusions
Infiltration of
periorbital
and
intraorbital fat
- Hypointense
infiltration of normal
intraorbital fat
- Diffuse
heterogeneous
enhancement
Heterogeneous
hyperintensity
Pre-Septal Orbital Cellulitis
There is mild to moderate right periorbital soft tissue thickening with
associated inflammatory stranding (yellow arrows). There is no post-septal
involvement. The intraconal fat is normal in appearance.
Note the thin curvilinear hyperdensity along the anterior surface of the right
globe (red arrow), from fluorescein used during slit lamp exam prior to CT.
Post-Septal Orbital Cellulitis
There is mild to moderate left periorbital soft tissue swelling and edema
with mild left proptosis (blue arrow). There are associated pre-septal
inflammatory changes along the inferior aspect of the orbit. There is a
subcentimeter subperiosteal rim enhancing focus along the medial orbital
wall, compatible with a small subperiosteal abscess (yellow arrow).
Post-Septal Orbital Cellulitis
Same case as prior slide.
Note the infiltrative
changes in the left
intraconal fat (yellow
arrow) in this patient with
left orbital post-septal
cellulitis. Note the normal
appearance of the
intraconal fat on the right
(red arrows).
Orbital Cellulits with Hyphema
There is an elliptical fluid
collection adjacent to the left
orbit with a punctate focus of
gas, which may represent an
abscess or effusion (red
arrows). There is also a soft
tissue density focus within the
anterior chamber of the left
globe (yellow arrow), and
thickening of the sclera.
Occular exam demontrated
100% hyphema (blood within the
anterior chamber)
Pathology demonstrated retinal
neovasuclarization with diffuse
vitrous hemorrage and
hyphema.
Conclusion
• CT and MRI are commonly used in the evaluation of the orbits and
globes.
• CT is optimal to evaluate bony structures and foreign bodies
whereas MRI has superior contrast resolution in the evaluation of
soft tissue structures.
• CT is the typically the imaging modality of choice in the evaluation of
acute orbital pathologies such as trauma and infection
• Familiarity with normal orbital anatomy and common acute orbital
pathologies is imperative for the radiologist who interprets such
exams.
References
•
Bord SP et al: Trauma to the globe and orbit. Emerg Med Clin North Am 2008;
26(1):97-123.
•
Grech R, Cornish KS, Galvin PL, et al. Imaging of Adult Ocular and Orbital Pathology
- a Pictorial Review. Journal of Radiology Case Reports 2014; 8(2):1-29.
•
Iinuma T, Hirota Y, Ishio K. Orbital wall fractures: Conventional views and CT.
Rhinology 1994; 32:81–83.
•
Kubal WS: Imaging of Orbital Trauma. Radiographics 2008; 28(6):1729-1739.
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Lee HJ, Jilani M, Frohman L, Baker S. CT of orbital trauma. Emerg Radiol
2004;10(4):168–172.
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Van Thong Ho, James F, McGuckin Jr, Smergel EM. Intraorbital Wooden Foreign
Body: CT and MR Appearance. Am J Neuro Surg 1996; 17:134–136.
•
Sung EK, Nadgir RN, Fujita A, et al. Injuries to the Globe: What can the Radiologist
Offer? Radiographics 2014; 34:764–776.