CT Neck with IV Contrast
For a patient with an abscessed tooth requiring evaluation to rule out Ludwig's angina, order a contrast-enhanced CT scan of the neck (soft tissue neck CT with IV contrast). 1
Imaging Protocol Specifics
Intravenous contrast is essential for detecting neck abscesses, especially those that are intramuscular, and for evaluating the extent of deep neck inflammation 1. The ACR Appropriateness Criteria explicitly state that CT can help identify a dental source of infection in the febrile patient and may be superior to ultrasound for evaluating the extent of deep neck inflammation 1.
Key Technical Points:
- Single-phase contrast-enhanced CT is sufficient - dual-phase imaging (with and without contrast) is not usually necessary 1, 2
- Standard coverage: skull base to thoracic inlet to adequately capture all structures 2
- Contrast helps distinguish vessels from lymph nodes and maps lesion borders 2
- CT provides superior spatial resolution and is more readily available than MRI 2
Clinical Rationale
Ludwig's angina is a rapidly progressive, potentially fatal cellulitis of the submandibular, sublingual, and submental spaces 3, 4. The infection can spread along fascial planes and lead to life-threatening complications including:
- Airway compromise (the greatest concern) 3, 5
- Mediastinitis 4, 5, 6
- Pleural empyema 5
- Pericarditis and pericardial tamponade 5
CT imaging is critical for:
- Confirming the diagnosis
- Determining the extent of infection spread
- Identifying drainable fluid collections/abscesses
- Detecting mediastinal involvement
- Guiding surgical planning 4, 6
Important Caveats
Patient must be stable enough to tolerate:
- Leaving the emergency department
- Lying supine during the scan 3
If the patient cannot safely leave the ED or tolerate supine positioning due to airway concerns, point-of-care ultrasound can serve as a useful adjunct 3. However, this does not replace CT for definitive evaluation.
Contrast Contraindications
Modify the protocol only if there is:
- Contrast allergy
- Renal insufficiency
- Pregnancy 2
In these situations, non-contrast CT may provide some information, though it is significantly less useful for characterizing abscesses and inflammation 1.
Why Not MRI?
While MRI offers superior soft tissue contrast 2, 4, CT is preferred in this acute setting because:
- Faster acquisition time (<5 minutes vs >30 minutes) 2
- Better patient tolerance
- More readily available
- Adequate for detecting abscesses and extent of infection
- Less susceptible to motion artifact from breathing 2
MRI may be considered if CT shows extensive disease requiring better soft tissue delineation, but it is not the initial study of choice 4.