CT Neck Soft Tissue Without Contrast for Airway and Infection Assessment
CT neck without contrast is insufficient for evaluating suspected deep neck infections, as IV contrast is essential for distinguishing abscesses from cellulitis and detecting vascular complications; however, it may be adequate for basic airway anatomical assessment in select scenarios.
Infection Assessment: Contrast is Essential
Deep Neck Infections Require Contrast Enhancement
IV contrast is mandatory for detecting neck abscesses, particularly intramuscular abscesses, and is the gold standard for identifying the source of infection and life-threatening complications including internal jugular vein thrombosis 1, 2.
Contrast-enhanced CT achieved a 92% correlation between radiographic evidence of abscess and surgical confirmation in deep neck infections, whereas non-contrast imaging cannot reliably differentiate fluid collections from cellulitis 3, 4.
Clinical evaluation alone underestimates disease extent in 70% of patients with deep neck infections; contrast-enhanced CT is the most important method for correct evaluation of cervical spaces involved and proper surgical planning 5.
Why Non-Contrast CT Fails for Infection
Without IV contrast, you cannot distinguish drainable abscesses from cellulitis, which fundamentally changes management from surgical drainage to medical therapy alone 4.
Non-contrast CT cannot detect vascular complications such as internal jugular thrombophlebitis (Lemierre's syndrome), mediastinitis extension, or septic embolization—all potentially fatal complications requiring immediate recognition 2, 4, 6.
The overall positive predictive value for abscess detection with contrast-enhanced CT is 79.6%, but this diagnostic capability is lost without contrast enhancement 7.
Airway Assessment: Limited Utility Without Contrast
When Non-Contrast May Be Acceptable
CT neck without contrast can assess basic airway anatomy including tracheal caliber, deviation, and stenosis in select cases where infection is not suspected 8.
For evaluating tracheomalacia or structural airway abnormalities, non-contrast CT with inspiratory and expiratory phases may be appropriate 8.
Critical Limitations for Airway Assessment
The American College of Radiology notes disagreement about whether neck CT without contrast alone is appropriate for pre- or post-treatment assessment of tracheal stenosis, indicating this is a controversial and suboptimal choice 8.
The limited z-axis coverage of isolated neck CT (without extending to chest) risks exclusion of the full extent of tracheal disease; combined neck and chest CT is preferred for comprehensive airway evaluation 8, 1.
When infection complicates airway pathology, CT with IV contrast becomes essential for assessing suspected posttreatment complications such as infection or bleeding 8.
Clinical Algorithm for Decision-Making
Order CT Neck WITH Contrast If:
- Any clinical suspicion of deep neck infection (fever, neck pain, swelling, erythema, odynophagia) 1, 2, 5.
- Concern for abscess formation requiring surgical drainage 3, 4.
- Risk of vascular complications (thrombophlebitis, septic emboli) 2, 4.
- Airway compromise in the setting of suspected infection 6.
- Need to evaluate extent of disease across multiple neck spaces 5.
Consider CT Neck WITHOUT Contrast Only If:
- Isolated structural airway assessment without infection concern 8.
- Contraindications to IV contrast (severe renal impairment, true contrast allergy) exist—though MRI without contrast would be superior in this scenario 1.
- Confirming fat-containing lesions or identifying sialoliths (rare indications) 1.
Common Pitfalls and Caveats
Never order non-contrast CT when infection is in the differential diagnosis—this represents substandard care that may delay appropriate surgical intervention and increase mortality risk 5, 4, 6.
Mortality from deep neck infections is 11.2% overall, with higher rates when complicated by septic shock or mediastinitis; early accurate diagnosis with contrast-enhanced CT is critical 6.
The parapharyngeal and retropharyngeal spaces are most commonly involved in deep neck infections, and more than one space is compromised in 90% of cases—information that cannot be adequately assessed without contrast 5, 7.
In pediatric neck infections, contrast-enhanced CT remains an excellent tool with 92% correlation to surgical findings, whereas non-contrast imaging provides inadequate information for surgical decision-making 3.
Airway obstruction, mediastinitis, and intracranial extension are life-threatening complications that require contrast-enhanced CT for detection 4, 6.