What is the preferred CT sinus imaging with or without contrast for diagnosing worsening sinusitis?

CT Sinus Imaging for Worsening Sinusitis

CT of the paranasal sinuses without contrast is the preferred imaging modality for evaluating worsening sinusitis in most cases, while CT with contrast should be used when complications are suspected. 1

Standard Approach to Sinus Imaging

Non-contrast CT

• Non-contrast CT is considered the gold standard for routine evaluation of sinusitis due to its superior depiction of:

  • Sinus anatomy
  • Soft-tissue changes
  • Bony structures (particularly the osteomeatal complex)
  • Potential anatomical factors contributing to recurrent or chronic sinusitis 2, 1

• Indications for non-contrast CT include:

  • Recurrent acute sinusitis
  • Chronic sinusitis
  • Preoperative planning for functional endoscopic sinus surgery
  • Nasal polyposis
  • Persistent nasal congestion/obstruction
  • Facial pressure/headache unresponsive to medical therapy 2

Contrast-enhanced CT

• CT with IV contrast is indicated when complications of sinusitis are suspected, including:

  • Orbital complications (periorbital cellulitis, subperiosteal abscess)
  • Intracranial complications (epidural/subdural collections)
  • Sinonasal tumors 2

• The addition of contrast allows for:

  • Better visualization of orbital and intracranial complications
  • Some differentiation of soft tissue opacification
  • Detection of vascular complications 2

Special Considerations

Immunocompromised Patients

• In immunocompromised patients, particularly those with hematological malignancies at risk for invasive fungal sinusitis, CT with IV contrast is recommended 2
• Classic CT findings for fungal disease include:
  • Unilateral lesions of one or more sinuses
  • Nodular mucoperiosteal thickening
  • Focal areas of bone destruction
  • Dense intrasinus concretions 2

Suspected Vascular Complications

• When vascular complications are suspected:
  • CT venography (CTV) for suspected venous thrombosis
  • CT angiography (CTA) for suspected mycotic aneurysm
  • These should be complementary to standard head and sinus CT, not stand-alone studies 2

Role of MRI in Sinusitis

• MRI is not the first-line imaging for routine sinusitis evaluation but is valuable as a complementary study when:

  • Aggressive sinus infection with orbital/intracranial complications is suspected
  • Invasive fungal sinusitis is suspected in immunocompromised patients
  • Evaluating sinonasal masses 1, 3

• MRI advantages:

  • Superior for soft tissue differentiation
  • More sensitive for detecting intracranial complications (93% vs 63% for CT) 2
  • Better at differentiating inflammatory conditions from neoplastic processes 4

Important Pitfalls to Avoid

1. Unnecessary imaging for uncomplicated acute sinusitis - Most cases can be diagnosed clinically without imaging 3

2. Performing both non-contrast and contrast CT - This doubles radiation exposure without significant additional diagnostic yield 2

3. Relying solely on imaging findings - Sinusitis cannot be diagnosed on imaging findings alone; correlation with clinical and endoscopic findings is essential 3

4. Failing to use contrast when complications are suspected - Complications may be missed without contrast enhancement 2

5. Performing imaging too soon after treatment - Imaging should be performed more than 4 weeks after acute bacterial sinusitis and after medical management if evaluating chronic sinusitis 2

By following these evidence-based guidelines for CT sinus imaging, clinicians can optimize diagnostic accuracy while minimizing unnecessary radiation exposure and healthcare costs.