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CT Maxillofacial (Sinus)

Non-contrast CT of the paranasal sinuses is the standard imaging test for chronic and recurrent rhinosinusitis and for mapping the surgical anatomy before functional endoscopic sinus surgery. Its high bony detail delineates the ostiomeatal complex, drainage pathways, septal and turbinate anatomy, and critical anatomical variants relevant to surgical safety. It also assesses facial fractures and screens for complications, with contrast reserved for suspected aggressive infection or neoplasm.

Indications

Chronic or recurrent rhinosinusitis refractory to medical therapy
Preoperative mapping of sinus anatomy before endoscopic sinus surgery
Nasal obstruction and evaluation of septal deviation or turbinate hypertrophy
Facial/midface trauma to assess sinus wall and orbital fractures
Suspected complications of sinusitis (orbital, intracranial) - often with contrast
Assessment of suspected sinonasal mass, mucocele, or fungal disease

Contraindications & Cautions

No absolute contraindication for the standard non-contrast study
Pregnancy: justify; the head is out of the primary pelvic beam but limit dose and use low-dose protocols
Radiation stewardship, particularly to the lens; use low-dose sinus CT protocols
Contrast (for suspected complications/tumor) requires renal function and allergy screening
Recent nasal surgery or acute epistaxis may alter mucosal appearances

Patient Preparation

No fasting for standard non-contrast sinus CT
Ideally image after a course of medical therapy so mucosal disease reflects true chronic change
Remove dentures, earrings, and other metallic objects from the field to reduce artifact
Position supine or prone; acquire volumetric data allowing multiplanar reformats
Explain breath-hold/stillness; sedation may be required in young children
Confirm the clinical question, surgical planning intent, and any prior imaging

Technique & Parameters

Thin-section (0.5-1.25 mm) volumetric non-contrast acquisition covering frontal sinus to hard palate
Reconstruct primary coronal, axial, and sagittal images in a bone (high-frequency) algorithm
Low-dose technique (reduced mAs) is standard given high inherent bone-air contrast
Review on bone (W2000-4000/L400-700) and soft-tissue windows
Coronal plane best demonstrates the ostiomeatal complex; sagittal aids frontal recess and sphenoethmoidal recess
Add IV contrast when orbital/intracranial complication or neoplasm is suspected

Systematic Review

Assess each sinus (maxillary, ethmoid, frontal, sphenoid) for mucosal thickening, opacification, and fluid levels
Evaluate the ostiomeatal complex and drainage pathways for obstruction
Examine the nasal septum for deviation/spurs and the turbinates for hypertrophy or concha bullosa
Identify surgically critical variants: Onodi (sphenoethmoidal) cell, Haller (infraorbital) cell, dehiscent lamina papyracea
Assess the skull base, cribriform plate, and fovea ethmoidalis height (Keros classification)
Review the orbits, optic canals, and carotid canals for dehiscence and proximity
Check bony walls for erosion, expansion, or fracture and inspect the dentition/alveolus

Key Findings & Significance

Mucosal thickening and ostiomeatal obstruction: chronic rhinosinusitis
Air-fluid level: acute sinusitis (or post-lavage/trauma)
Hyperdense sinus content with bony expansion/erosion and calcifications: fungal sinusitis
Expansile opacified sinus with wall remodeling: mucocele
Bony erosion with a soft-tissue mass: neoplasm (benign or malignant) - characterize further with contrast/MRI
Septal deviation, spurs, concha bullosa, and other variants contributing to obstruction
Sinus wall or orbital floor fracture with herniation or emphysema in trauma

Differential Considerations

Unilateral sinus opacification: fungal sinusitis vs neoplasm vs obstructing polyp/mucocele vs odontogenic source
Hyperdense sinus contents: inspissated secretions/fungal disease vs hemorrhage vs calcified mass
Expansile sinus lesion: mucocele vs polyp vs benign tumor (e.g., inverted papilloma) vs malignancy
Diffuse polypoid mucosal disease: chronic polyposis vs allergic fungal sinusitis vs cystic fibrosis
Bony sclerosis/thickening: chronic osteitis vs fibrous dysplasia vs osteoma
Opacified maxillary sinus with adjacent tooth: odontogenic sinusitis vs primary sinus disease

Pearls & Pitfalls

Always flag surgically dangerous variants (Onodi cell, dehiscent lamina papyracea/carotid, low skull base) for the surgeon
Report Keros classification of the olfactory fossa depth to alert to CSF-leak risk
Unilateral opacification, bone erosion, or calcification should prompt concern for fungal disease or neoplasm, not simple sinusitis
Image after medical therapy where possible; transient viral mucosal change overestimates chronic disease
Correlate maxillary sinus disease with the adjacent dentition to identify an odontogenic source
Assess the orbit and skull base carefully when infection is aggressive - complications change management

Structured Report

State technique (non-contrast low-dose sinus CT) and comparison
Report mucosal disease and drainage-pathway (ostiomeatal complex) patency per sinus
Describe septal and turbinate anatomy and any obstructing variants
List surgically relevant anatomical variants and skull-base/orbital relationships
Note bone erosion, expansion, fractures, and any features concerning for fungal disease or neoplasm
Impression: dominant diagnosis, surgical anatomy summary/caveats, and any recommendation for contrast MRI/biopsy

References

ACR Appropriateness Criteria: Sinonasal Disease
European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS)
ACR-ASNR-SPR Practice Parameter for the Performance of Sinonasal CT
Som & Curtin, Head and Neck Imaging

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CT Maxillofacial (Sinus)

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References