Learning objectives
To review imaging anatomy of the orbits.
To focus on extraconal pathologies including osseous orbital lesions.
To provide a pictorial review of extraconal and osseous orbital pathologies and put forward an algorithm for image interpretation.
Background
We ask what pathologies can be found at the periphery of the orbits in imaging and how can we achieve accurate diagnosis.First step to correct diagnosis of these entities is profound knowledge of orbital anatomy in CT and MRI.
Most helpful is the differentiation of four orbital compartments: ocular,
conal,
intra- and extraconal compartment.
Location of a lesion to the orbits,
followed by locating a lesion to its orbital compartment and clinical information will lead to the differential diagnosis.
However,
some lesions extend beyond these...
Imaging findings OR Procedure details
The following cases of our pictorial review show various pathologies affecting the extraconal space that we have recently seen in our day-to-day routine.
We have chosen to present them point by point covering:
1) trauma
2) infection
3) tumor and tumor-like lesions
In addition we will deal with pathologies originating from neighbouring structures that can affect the orbits.
Trauma
CT is the mainstay for evaluation of orbital trauma.
Orbital fractures can be isolated or be part of more complex facial fractures.
Bony fractures are evident...
Conclusion
Take-Home Imaging Algorithm
1. Locate lesion to orbit.
2. Locate lesion to orbital compartment.
3. Incorporate clinical information (trauma,
infection,
tumor or tumor-likelesion),
analyse imaging features in CT and MRI andprovide differential diagnosis.
KIS principle = keep it simple and practial.
4. For residents: Perform radiologic - pathologic correlations when histologic diagnosis is established.
References
Kubal W.
Imaging of orbital trauma.
RadioGraphics 2008; 28:1729-39.
LeBedis CA,
Sakai O.
Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting.
Radiographics 2008; 28:1741-53.
Goh PS,
Gi MT,
Charlton A et al.
Eur J Radiol 2008; 66:387-95.
Aviv RI,
Casselman J.
Orbital Imaging: Part 1.
Normal anatomy.
Clin Radiol 2005; 60:279-87.
Aviv RI,
Miszkiel K.
Orbital Imaging: Part 2.
Intraorbital Pathology.
Clin Radiol 2005; 60:288-307
