What is the recommended initial imaging modality for patients presenting with sinus symptoms?

Initial Imaging Modality for Patients with Sinus Symptoms

Non-contrast CT of the maxillofacial region is the recommended initial imaging modality for patients presenting with sinus symptoms when imaging is clinically indicated. 1

When Imaging is Indicated

Imaging should not be routinely ordered for uncomplicated cases of sinusitis. The following scenarios warrant imaging:

• Symptoms persisting without improvement for at least 10 days despite medical therapy
• "Double sickening" pattern (symptoms worsen within 10 days after initial improvement)
• Acute recurrent sinusitis
• Chronic rhinosinusitis (symptoms lasting >12 weeks)
• Sinonasal polyposis
• Suspected complications (orbital or intracranial)
• Pre-surgical planning

Imaging Modality Selection

First-Line Imaging: Non-contrast CT Maxillofacial

• Provides accurate depiction of sinus anatomy and soft-tissue changes
• Detailed visualization of the osteomeatal complex
• Allows multiplanar reconstruction
• Considered the gold standard for routine sinus evaluation 2, 1
• Essential for surgical planning if intervention becomes necessary

When to Use Contrast-Enhanced CT

Contrast should be added in specific scenarios:

• Suspected orbital complications
• Suspected intracranial extension
• Suspected cavernous sinus thrombosis
• Suspected invasive fungal sinusitis (particularly in immunocompromised patients)
• Suspected sinonasal mass or neoplasm 2, 1

Role of MRI

MRI is not first-line for routine sinusitis evaluation but is indicated for:

• Better differentiation of mucosal thickening from secretions
• Detection of intracranial complications (97% diagnostic accuracy vs. 87% for CT) 3
• Suspected fungal sinusitis
• Differentiating inflammatory disease from tumors 1, 4

Plain Radiography

• No longer recommended for routine sinus imaging
• Poor sensitivity (25-41% for most sinus groups, 80% for maxillary sinuses only) 2, 1
• Limited in evaluation of soft-tissue structures

Special Populations

Immunocompromised Patients

• Lower threshold for imaging due to risk of invasive fungal sinusitis
• Contrast-enhanced CT is recommended 2
• Consider MRI for early detection of fungal invasion 2

Pregnant Women

• Ultrasonography recommended to avoid radiation exposure 1

Children

• Lower-dose CT protocols preferred
• MRI may require sedation in young children 2

Common Pitfalls to Avoid

1. Overuse of imaging for uncomplicated sinusitis: Diagnosis should be based on clinical findings for uncomplicated cases
2. Performing both non-contrast and contrast CT: Doubles radiation exposure without significant additional diagnostic yield
3. Failing to use contrast when complications are suspected: May result in missed complications
4. Imaging too soon after treatment: Wait at least 4 weeks after acute bacterial sinusitis treatment
5. Relying on plain radiographs: Inadequate sensitivity and specificity

Imaging for Suspected Complications

For patients with suspected orbital or intracranial complications:

• Start with contrast-enhanced CT maxillofacial to include orbits and brain
• Follow with MRI if intracranial complications are suspected or not adequately visualized on CT
• Consider adding MR venography for suspected venous thrombosis 2

By following these evidence-based guidelines for sinus imaging, clinicians can ensure appropriate use of diagnostic resources while optimizing patient outcomes and minimizing unnecessary radiation exposure.