What a CT Orbits Scan Shows
CT of the orbits is the most useful imaging modality for evaluating orbital trauma and is the most accurate method for detecting fractures, soft tissue injuries, hemorrhage, and intraocular foreign bodies. 1
Anatomical Structures Visualized on CT Orbits
Bony Structures
- Orbital walls (medial, lateral, floor, and roof)
- Orbital rims
- Orbital apex
- Optic canal
- Superior and inferior orbital fissures
- Adjacent paranasal sinuses
Soft Tissue Structures
- Globe integrity and internal structures
- Extraocular muscles (size, position, and enhancement)
- Optic nerve and sheath
- Orbital fat
- Lacrimal gland and apparatus
- Vascular structures (superior ophthalmic vein)
Clinical Applications of CT Orbits
Trauma Evaluation
- Fracture detection with 94.9% sensitivity 1
- Soft tissue injuries including globe damage 1
- Hemorrhage within the orbit 1
- Foreign body detection, especially metallic or glass (94.9% sensitivity) 1
- Muscle entrapment in orbital fractures 2
- Air in the orbit suggesting communication with adjacent air-filled structures 2
Non-Traumatic Conditions
- Orbital masses and lesions
- Inflammatory conditions (thyroid eye disease, orbital inflammatory syndrome)
- Orbital asymmetry and proptosis 1
- Vascular abnormalities
Technical Considerations
- Thin-section axial imaging with multiplanar reconstructions provides optimal evaluation 2
- Non-contrast CT is typically sufficient for trauma evaluation 1
- Contrast enhancement may be helpful for evaluating masses or inflammatory conditions 1
CT Orbits vs. Other Imaging Modalities
Advantages Over MRI
- Superior for fracture detection 1
- Better visualization of bony anatomy 1
- Faster acquisition time (critical in trauma)
- Detection of metallic foreign bodies 1
- No contraindications related to metallic implants
Limitations Compared to MRI
- Less detailed soft tissue characterization 1
- Limited evaluation of optic nerve pathology 1
- Radiation exposure
- Less sensitive for wooden foreign bodies (may be mistaken for air) 1
Common Pitfalls to Avoid
- Relying solely on radiographs for orbital trauma is insufficient 1, 2
- Missing subtle fractures or intracranial extension 2
- Overlooking small foreign bodies
- Failure to use a systematic approach when evaluating orbital trauma 3
CT orbits provides critical diagnostic information that guides clinical and surgical management decisions, particularly in trauma cases where rapid and accurate assessment is essential for preventing vision loss and preserving orbital function.