What test confirms sinusitis?

Diagnostic Tests for Confirming Sinusitis

CT scan without contrast is the gold standard imaging modality for confirming sinusitis when imaging is clinically indicated. 1

Clinical Diagnosis

• The diagnosis of acute sinusitis is primarily based on clinical history and physical examination, with imaging reserved for specific situations 2
• Presence of 2 or more symptoms (nasal obstruction, facial congestion/pressure, discolored nasal discharge, hyposmia) for >12 weeks is highly sensitive for chronic rhinosinusitis (CRS), but confirmation requires documentation of inflammation on endoscopy or imaging 2
• In most instances, the diagnosis of acute sinusitis is made presumptively based on symptoms and clinical examination, and treatment is initiated without imaging 2

When Imaging Is Indicated

• Imaging should be considered in cases of:
  • Persistent sinusitis (symptoms lasting >4 weeks) 1
  • Recurrent or chronic sinusitis 1
  • Suspected complications (orbital or intracranial) 1
  • Need for surgical planning 2
  • When symptoms are vague or physical findings are equivocal 2

Preferred Imaging Modalities

CT Scan

• Non-contrast CT is the preferred imaging modality for evaluating sinusitis 1, 2
• CT provides excellent bony detail and accurately depicts sinus anatomy and soft-tissue changes 1, 3
• CT can identify anatomic variants that may narrow sinus drainage pathways or increase risk during surgery 2
• Findings that confirm sinusitis include mucosal thickening, sinus opacification, polyps/retention cysts, and sclerosis/thickening of sinus walls 2
• CT with IV contrast should be reserved for cases with suspected complications and should include coverage of sinuses, orbits, and brain 1

Cone Beam CT (CBCT)

• CBCT has high accuracy for evaluating both odontogenic and non-odontogenic sinusitis 2
• Shows strong agreement with sinus endoscopy findings 2
• Limited in evaluation of soft-tissue structures compared to standard CT 2

MRI

• Not first-line for sinusitis diagnosis 1, 4
• Reserved for suspected intracranial complications, fungal sinusitis, or neoplasm 1, 4
• Better than CT for differentiating soft-tissue structures 3
• More accurate (97%) than CT (87%) in determining intracranial complications 5

Plain Radiography

• Limited role in sinusitis management 3
• Air-fluid levels and complete opacification of a sinus are specific for sinusitis but only seen in 60% of cases 3
• Five views are required to achieve 88% sensitivity for maxillary sinusitis 2
• Not recommended for routine diagnosis of sinusitis 3

Special Considerations

• In ICU patients, a high index of suspicion is needed for nosocomial sinusitis, and CT is the preferred diagnostic imaging 1
• For suspected ventilator-associated sinusitis, radiography of the maxillary sinuses should be performed first to detect fluid; if negative, proceed to CT 2
• When radiography or CT demonstrates fluid in the sinuses, antral puncture should be performed for definitive diagnosis and therapeutic drainage 2

Common Pitfalls

• Radiologic findings may not correlate with symptom severity 2, 6
• CT findings can be nonspecific; clinical correlation is needed to avoid overdiagnosis 3
• Patients with suspected "recurrent acute sinusitis" and normal CT between episodes rarely have abnormal CT findings during acute symptom exacerbations 6
• Unnecessary imaging for uncomplicated acute sinusitis should be avoided 1

By following these evidence-based guidelines for diagnostic testing, clinicians can accurately confirm sinusitis while avoiding unnecessary imaging studies.