NCCT Scan for Suspected Neck Foreign Body
For suspected foreign body in the neck, CT without IV contrast is the recommended imaging modality after initial radiographs, as it provides superior sensitivity (90-100%) for detecting both radiopaque and radiolucent foreign bodies compared to plain films alone. 1, 2
Initial Imaging Approach
Start with plain radiographs of the neck as the first-line screening modality, which can demonstrate radiopaque foreign bodies (metal, stone, glass), soft-tissue swelling, airway competency, and subcutaneous emphysema 1
Plain radiographs have significant limitations, with false-negative rates up to 47% for esophageal foreign bodies and up to 85% for food bolus, fish bones, chicken bones, and non-radiopaque objects like wood or plastic 2, 3
When to Proceed with CT Without Contrast
CT without IV contrast is rated as "usually appropriate" (rating 7/9) for suspected foreign body with negative radiographs 1
Key Advantages of NCCT:
Superior detection capability: CT is 5-15 times more sensitive than radiography for detecting foreign bodies, with overall sensitivity of 90-100% and specificity of 93.7-100% 1, 2, 4
Detects radiolucent materials: Wood, plastic, and rubber appear moderately hyperdense on CT despite being radiolucent on plain films 1
Precise localization: CT provides exact anatomic location and can identify material composition based on Hounsfield unit values 1
Evaluates complications: Detects cellulitis, abscess formation, soft tissue gas, vascular injury, and airway compromise 1, 2
Technical Considerations:
Use thin slice thickness (1 mm) to avoid missing small foreign bodies 1
Obtain both soft tissue and bone windows for comprehensive evaluation 4
Avoid IV contrast initially as it may obscure identification of the foreign body 1
Why Not Contrast-Enhanced CT First?
Contrast administration is rated as "may be appropriate" (rating 6/9) but is specifically noted to potentially obscure foreign body identification 1
Contrast is reserved for specific indications: Evaluating vascular complications, pseudoaneurysms, or when assessing extent of infection after foreign body is localized 1
Alternative Modalities and Their Limitations
Ultrasound:
- Rated as "usually appropriate" (rating 8/9) for radiolucent foreign bodies like wood or plastic 1
- Limited by: Overlying soft tissue injury, cervical collars, skin dressings, and poor evaluation of deep structures in zones I and III 1
MRI:
- Contraindicated as initial study due to concern for metallic foreign bodies causing heating, motion artifact, and potential patient harm 1
- Lower sensitivity than CT for detecting foreign bodies, though superior for soft tissue complications once foreign body is excluded or localized 1
Clinical Context Matters
For Penetrating Neck Injury:
If hemodynamically unstable with "hard signs" (active hemorrhage, expanding hematoma, airway compromise): proceed directly to surgery without imaging 1
If stable with "soft signs" (non-expanding hematoma, dysphagia, subcutaneous emphysema): CTA with IV contrast becomes first-line to evaluate vascular and aerodigestive injury 1
For Ingested/Impacted Foreign Bodies:
CT scan is essential when plain films are negative but symptoms persist, or when evaluating for perforation 2, 4
Emergent endoscopy (within 2-6 hours) is required for complete esophageal obstruction or sharp objects, regardless of imaging 2
Common Pitfalls to Avoid
Do not rely solely on patient-reported location of foreign body sensation, as correlation with actual location is poor (kappa 0.27) 5
Do not skip CT if clinical suspicion is high despite negative radiographs, especially for non-radiopaque materials 2, 4
Do not order MRI before excluding metallic foreign bodies with radiographs or CT 1
Do not use CT with and without contrast as this is rated "usually not appropriate" and provides no additional benefit for foreign body detection 1