When Are Sinus X-Rays Indicated?
Sinus X-rays (plain radiography) are generally NOT indicated for the diagnosis or management of sinusitis in most clinical scenarios. 1, 2
Primary Recommendation: Avoid Plain Radiography
The American Academy of Otolaryngology-Head and Neck Surgery and the American College of Radiology explicitly state that radiographic imaging should NOT be performed for patients with clinically diagnosed acute rhinosinusitis unless a complication or alternative diagnosis is suspected. 1, 2, 3
Why Plain Films Are Not Recommended:
- Poor sensitivity and specificity: Plain radiographs have significant false-positive and false-negative results, with sensitivity as low as 25-41% for most sinus groups (except maxillary sinuses at 80%) 1, 2, 4
- Limited anatomic visualization: Plain films cannot adequately evaluate the ethmoid, frontal, or sphenoid sinuses, and provide no soft-tissue detail for assessing complications 1
- Clinical diagnosis is sufficient: Acute bacterial rhinosinusitis is diagnosed clinically when purulent nasal discharge plus nasal obstruction or facial pain/pressure persist ≥10 days without improvement, or worsen within 10 days after initial improvement 1, 2, 3
When Imaging IS Indicated (Use CT, Not X-rays)
If imaging becomes necessary, CT without contrast is the gold standard—NOT plain radiography. 1, 2
Specific Indications for CT Imaging:
For Acute Sinusitis:
- Suspected complications (orbital cellulitis, subperiosteal abscess, intracranial extension, cavernous sinus thrombosis) 1
- Immunocompromised patients with fever 1
- Severe symptoms with diagnostic uncertainty or alternative diagnosis suspected 1, 2
For Chronic/Recurrent Sinusitis:
- Chronic rhinosinusitis (symptoms >12 weeks) requiring confirmation of diagnosis 1
- Recurrent acute sinusitis (≥4 episodes per year) 1
- Pre-operative planning for functional endoscopic sinus surgery 1
- Nasal polyposis 1
- Persistent nasal congestion/obstruction unresponsive to medical therapy 1
- Suspected silent sinus syndrome or mucocele 1, 5
- Suspected fungal sinusitis 1
Critical Timing: All imaging should be performed >2 weeks after an upper respiratory infection and >4 weeks after acute bacterial sinusitis treatment to avoid false-positive findings from residual inflammation 1
Clinical Pitfalls to Avoid:
- Do not order imaging for uncomplicated acute sinusitis: The diagnosis is clinical, and imaging does not distinguish bacterial from viral etiology 1, 3
- Do not use plain films when CT is needed: If clinical severity requires diagnostic certainty (complications, surgical planning), proceed directly to CT rather than obtaining inadequate plain films first 4, 6
- Recognize that mucosal thickening on imaging is nonspecific: Up to 40% of asymptomatic adults show sinus abnormalities on CT, requiring clinical correlation 4, 7
When MRI Is Preferred Over CT:
Use MRI with contrast (not plain films or CT) for:
- Suspected sinonasal tumor or malignancy 1
- Skull base dehiscence with opacification 1
- Intracranial complications (meningitis, brain abscess, subdural empyema) where MRI has 97% diagnostic accuracy versus 87% for CT 1
- Differentiating tumor from retained secretions 1
- Suspected invasive fungal sinusitis 1, 7
Bottom line: Plain sinus X-rays have been supplanted by CT when imaging is necessary and should be considered obsolete for sinusitis evaluation. 1, 4