Recommended Imaging for Sinusitis

For uncomplicated acute sinusitis, no imaging is recommended—diagnosis should be based on clinical criteria alone. 1, 2

Clinical Scenarios and Imaging Recommendations

No imaging is indicated for straightforward acute sinusitis in both adults and children 1, 2
Plain radiographs, CT, and MRI are all inappropriate when clinical diagnosis is clear 1
This applies regardless of patient age, as the diagnosis relies entirely on clinical presentation 1

Non-contrast CT of the paranasal sinuses is the gold standard imaging modality when imaging becomes necessary 1, 2

Key advantages of CT include:

Accurately depicts sinus anatomy, soft-tissue changes, and the osteomeatal complex 1, 2
Essential for preoperative planning before functional endoscopic sinus surgery 1
Low-dose CT protocols deliver radiation equivalent to only two plain radiographic views 1
Multidetector CT allows axial acquisition with coronal and sagittal reconstructions, avoiding direct orbital radiation 1

Contrast administration is not needed when CT is performed solely to define anatomy or confirm chronic sinusitis 1

MRI is not first-line for sinusitis but has specific roles 1, 2:

Use MRI with contrast when:

Suspected intracranial complications (meningitis, epidural/subdural abscess, brain abscess) 1
Suspected orbital complications requiring soft-tissue differentiation 1
Evaluating for invasive fungal sinusitis in immunocompromised patients 1
Differentiating sinonasal mass from retained secretions or neoplasm 1
Skull base involvement or intracranial extension 1

Limitations of MRI:

Poor visualization of bony anatomy and osteomeatal complex 1
Less sensitive for bony erosions 1
May require sedation in young children 1
Cannot distinguish normal edematous mucosa from diseased tissue 1
Higher sensitivity (85-86%) than CT (57-69%) for invasive fungal sinusitis complications 1

CT with IV contrast covering sinuses, orbits, and brain is indicated when complications are suspected 1, 2

Warning signs requiring contrast-enhanced imaging:

MRI with contrast should complement CT in these scenarios, as it is more sensitive (93% vs 63%) for intracranial complications 1

Immunocompromised patients:

Lower threshold for imaging due to invasive fungal sinusitis risk 1, 2
CT may show periantral fat obliteration, bone erosion, and orbital/intracranial extension 1
MRI demonstrates lack of mucosal enhancement ("black turbinate sign") indicating necrosis 1
Combined CT and MRI often necessary for complete evaluation 1

Pediatric considerations:

Critical timing considerations:

Perform imaging >2 weeks after upper respiratory infection 1
Wait >4 weeks after acute bacterial sinusitis treatment before imaging for chronic disease 1
This prevents false-positive findings from residual inflammation 1

Avoid imaging uncomplicated acute sinusitis—it adds no diagnostic value and increases costs 1, 2
Do not use CT without contrast alone when complications are suspected—soft-tissue abnormalities may be missed 1
Do not rely on plain films—they miss significant pathology and have unacceptably high false-negative rates 1, 3
Remember clinical correlation is essential—CT shows incidental sinus abnormalities in 40% of asymptomatic adults 3
Avoid premature imaging—wait appropriate intervals after acute infection to prevent overdiagnosis 1