Should a patient with suspected sinus issues and potential history of kidney disease or allergies undergo a computed tomography (CT) scan of the sinuses with or without contrast?

CT Sinus Imaging: Contrast vs Non-Contrast

For most sinus imaging indications, you should obtain a CT of the sinuses WITHOUT contrast. 1

Standard Approach for Common Sinus Conditions

Uncomplicated Acute or Chronic Sinusitis

• Non-contrast CT is the standard and preferred imaging modality 1
• Provides optimal visualization of bone anatomy, sinus drainage pathways, and mucosal disease 1
• Sufficient for pre-surgical planning before functional endoscopic sinus surgery 1
• Contrast adds no diagnostic value and unnecessarily increases radiation exposure 1

Recurrent Acute Rhinosinusitis (RARS)

• Non-contrast CT is recommended prior to surgical intervention 1
• Best demonstrates anatomic variants and osteomeatal complex obstruction 1

When Contrast IS Indicated

Suspected Complications (High Morbidity/Mortality Scenarios)

You MUST use contrast when evaluating for:

Orbital Complications

• CT with IV contrast is required to detect orbital cellulitis, subperiosteal abscess, or orbital abscess 1
• Non-contrast CT inadequately visualizes these soft-tissue complications and may miss life-threatening pathology 1
• Accuracy for detecting orbital complications: 87-91% with contrast CT 1

Intracranial Complications

• CT with IV contrast is essential for epidural abscess, subdural empyema, meningitis, cerebritis, or brain abscess 1
• MRI with contrast is actually superior (97% accuracy vs 87% for CT), but contrast CT is acceptable when MRI is unavailable or contraindicated 1
• Non-contrast CT alone provides insufficient anatomical coverage and misses critical complications 1

Invasive Fungal Sinusitis

• Non-contrast CT is typically performed first for initial evaluation and surgical planning 1
• Add contrast when evaluating for orbital or intracranial extension, cavernous sinus thrombosis, or vascular complications 1
• This is a high-mortality condition (50-80% mortality) requiring aggressive imaging in immunocompromised patients 1

Suspected Sinonasal Mass

• Non-contrast CT best defines bone erosion and cartilaginous/bone matrix 1
• Add contrast only if MRI is unavailable or contraindicated 1
• MRI with and without contrast is actually the preferred modality for soft-tissue characterization 1

Critical Decision Algorithm

Use this stepwise approach:

1. Is this uncomplicated sinusitis (acute, chronic, or recurrent)?

   • YES → Non-contrast CT only 1

2. Are there signs of orbital involvement (proptosis, eye swelling, impaired eye movement, decreased visual acuity)?

   • YES → CT with IV contrast mandatory 1

3. Are there signs of intracranial involvement (severe headache, altered consciousness, seizures, focal neurologic deficits, cranial nerve palsy)?

   • YES → CT with IV contrast mandatory (consider MRI with contrast as superior alternative) 1

4. Is the patient immunocompromised (leukemia, poorly controlled diabetes, transplant on high-dose steroids) with fever and sinonasal symptoms?

   • YES → Start with non-contrast CT; add contrast if orbital/intracranial extension suspected 1

5. Is there a suspected mass (persistent pain, nasal obstruction, epistaxis)?

   • YES → Non-contrast CT for bone detail; MRI with contrast preferred for soft-tissue characterization 1

Important Caveats

Dual-Phase Imaging

• Never obtain both non-contrast AND contrast CT (dual-phase imaging) 1
• This doubles radiation exposure without additional diagnostic yield 1

Kidney Disease Considerations

• If significant renal impairment exists and contrast is indicated for complications, MRI with contrast is preferred over CT with contrast 1
• MRI provides superior soft-tissue resolution (93% vs 63% sensitivity for intracranial complications) 1

Allergy Considerations

• If true contrast allergy exists and imaging for complications is needed, MRI with contrast after appropriate premedication is preferred 1
• Alternatively, non-contrast CT can be performed but has significant limitations in detecting soft-tissue complications 1

Radiation Exposure

• Low-dose CT protocols reduce effective dose to approximately 3% of standard CT while maintaining diagnostic accuracy 2
• Cone beam CT offers 30-40% dose reduction compared to standard CT but has limited soft-tissue visualization 3