II. Epidemiology
- High False Positive Rate
- Upper Respiratory Infection: 85% with CT changes
- Asymptomatic adults: 40% with CT changes
- References
III. Advantages
- Much more sensitive than Sinus XRay
- Good Sinus Anatomy definition
- Views sphenoid and Ethmoid Sinuses well
- Defines osteomeatal complex well
IV. Indications
- Confusing presentation
- Evaluation before endoscopic surgery
-
Sinusitis refractory to maximal medical management
- Recurrent Acute Sinusitis
- Persistent Chronic Sinusitis Symptoms
- Suspected Osteomeatal complex Occlusion
- Suspected Allergic Fungal Sinusitis
- Suspected Fungal Sinusitis or other complicated Sinusitis (e.g. Immunocompromised patients)
- Sinusitis complications (e.g. Cavernous Sinus Thrombosis)
V. Technique
- Full Coronal non-contrast Sinus CT
- Standard view indicated in most cases
- Mucosal thickening >5mm is consistent with sinus infection
- Demonstrates fluid and mucosal edema, as well as bony destruction
- Fat stranding (increased density) may be present in para-sinus spaces
- Limited Sinus CT
- Consider as alternative to full Sinus CT
- Four non-contiguous 5 mm slices in coronal plane
- Frontal Sinus
- Anterior ethmoid and Maxillary Sinuses
- Posterior ethmoid and Maxillary Sinuses
- Sphenoid Sinus
- Advantages
- Less expensive
- Less radiation
- Disadvantage
- Unknown efficacy
- Contrast Sinus CT
- Indications
- Periorbital Cellulitis or abscess
- Vascular complications
- Cavernous Sinus Thrombosis
- Findings
- Necrotic tissue and fluid does not contrast enhance
- Inflamed, thickened mucosa contrast enhances
- Mucosa, fluid and soft tissue may be indistinguishable without contrast
- Consider IV contrast in complicated cases (e.g. vascular complications, Cavernous Sinus Thrombosis)
- Indications
VI. Timing
- Perform during maximal medical therapy
- Delay if URI present
VII. Contraindications: Relative
- Submaximal medical Management
- Upper Respiratory Infection
- Acute sinus infection
VIII. Interpretation
- Findings consistent with Rhinosinusitis
- Air-fluid levels
- Total opacification
- Mucosal thickening >5 mm
- Complications identified by Sinus CT
- Osteomeatal Complex Obstruction
- Allergic Fungal Sinusitis
IX. References
- Broder (2018) Crit Dec Emerg Med 32(10): 12-3
- Mukherji (1998) Radiology 207:417-22 [PubMed]
- Okuyemi (2002) Am Fam Physician 66:1882-6 [PubMed]