CT Scan for Possible Orbital Fracture
Order a non-contrast thin-section CT of the orbits with multiplanar reconstructions as the first-line imaging study for suspected orbital fracture. 1, 2
Recommended CT Protocol
- Non-contrast CT orbits with thin sections (1-3mm) and multiplanar reconstructions is the gold standard for evaluating orbital trauma 1, 2
- Axial 1-mm slices and coronal 3-mm slices provide optimal anatomic detail 3
- Coronal reformations can be performed if the patient cannot tolerate prone positioning for direct coronal imaging 3
- Contrast is not needed in the acute trauma setting unless vascular complications are specifically suspected 2, 4
Why CT Orbits is the Optimal Choice
- Superior fracture detection: CT provides excellent visualization of the osseous orbit and is the most accurate method for detecting fractures of the orbital floor, medial wall, roof, and lateral wall 1, 2
- Soft tissue evaluation: CT effectively identifies muscle entrapment, hemorrhage, globe injury, and displaced fracture fragments 1, 3
- Foreign body detection: CT has 94.9% sensitivity for detecting intraorbital foreign bodies, particularly metallic or glass fragments 1, 2
- Rapid acquisition: CT can be performed quickly in the acute trauma setting, which is critical when evaluating potentially unstable patients 5
When to Add CT Head
Add non-contrast CT head to the CT orbits study when: 1, 4
- Intracranial injury is suspected based on mechanism or clinical presentation
- Orbital roof fracture is identified (concern for associated calvarial fracture or CSF leak)
- The patient has altered mental status or other signs of head trauma
Clinical Scenarios Requiring Urgent CT Orbits
Order CT orbits immediately for patients presenting with: 1, 2
- Periorbital soft tissue swelling or ecchymosis after trauma
- Diplopia or restricted ocular movement
- Vision loss or visual field defects
- Hyphema or subconjunctival hemorrhage
- Suspected muscle entrapment (especially with bradycardia, nausea, or oculocardiac reflex) 1
- Concern for open globe injury or intraorbital foreign body
Critical Pitfalls to Avoid
- Do not order plain radiographs: Plain films are insufficient for detecting orbital pathology and have been replaced by CT in current practice 1, 2
- Avoid MRI as initial imaging: MRI is contraindicated when metallic foreign bodies are suspected due to risk of object movement from the magnetic field 1, 4
- Do not delay imaging for soft tissue swelling: While edema may limit clinical examination, CT should be obtained promptly to identify fractures and muscle entrapment that require urgent intervention 1
- Recognize trap-door fractures in children: Pediatric patients may have minimal external signs ("white-eyed blowout fracture") but significant muscle entrapment requiring immediate surgical repair 1
When MRI May Be Complementary
MRI can be obtained after initial CT evaluation in specific circumstances: 1
- More detailed assessment of extraocular muscles and orbital soft tissues is needed for surgical planning
- Suspected wooden foreign body (appears hypoattenuating on CT and may be mistaken for air) 1
- Evaluation of the optic nerve when CT findings are equivocal
- Dynamic imaging is desired for complex strabismus evaluation