Best Imaging Study for Periorbital Fracture
CT of the orbits without IV contrast is the most appropriate initial imaging study for evaluating periorbital fractures. 1, 2, 3
Rationale for CT Orbits as First-Line Imaging
- Non-contrast thin-section orbital CT with multiplanar reconstructions provides excellent anatomic definition of orbital structures and is considered the gold standard for evaluating orbital trauma 1, 4
- CT has superior capability for identifying the integrity of the osseous orbit and skull base, and is particularly useful in detecting fractures and displaced fracture fragments 1, 4
- CT provides detailed imaging of both bony structures and soft tissues, allowing comprehensive assessment of injury extent 4
- CT has 94.9% sensitivity for detection of intraorbital foreign bodies, especially metallic ones, which may be present in traumatic injuries 2, 3
CT Protocol Recommendations
- Thin-section axial scans with multiplanar reformatted images should be obtained 5
- Contrast is typically not needed in the trauma setting 1, 2
- Spiral CT technique may be beneficial in acutely injured patients due to its rapid scan time and ability to provide smooth data sets for three-dimensional reformations 6
Clinical Scenarios Requiring CT Orbit
- Patients with periorbital soft tissue swelling, ecchymosis, hyphema, subconjunctival hemorrhage, diplopia, restriction of ocular movement, or vision loss 1
- When there is suspicion of orbital wall fractures (floor, medial wall, roof, or lateral wall) 1, 7
- When there is concern for entrapment of extraocular muscles, particularly in children who are prone to "trap door" orbital fractures 1
Important CT Parameters for Treatment Decision-Making
- Fracture size and location 7
- Orbital volume changes 7
- Soft tissue involvement, including muscle entrapment 7
- Craniocaudal dimension of the fracture 7
Complementary Imaging Considerations
- CT of the head without IV contrast may have a complementary role when obtained along with CT orbits in cases where intracranial abnormality or calvarial fracture is suspected 1
- MRI is contraindicated when metallic foreign bodies are suspected due to potential movement of the object caused by the magnetic field 2, 3
- CT angiography (CTA) may be indicated if vascular injury is suspected, but is not typically the initial imaging test for orbital trauma 1
Pitfalls to Avoid
- Plain radiographs are insufficient for detecting orbital pathology and have been largely replaced by CT 1, 5
- Wooden foreign bodies may appear hypoattenuating on CT and can be mistaken for air; MRI may be useful as a supplementary imaging modality in these specific cases, but only after metallic foreign bodies have been ruled out 2
- Contrast-enhanced CT is generally unnecessary for initial evaluation of orbital fractures unless vascular complications are suspected 1, 6