Sinus CT

Aka: Sinus CT, CT Sinus, CT of paranasal sinuses

1. See Also
   1. Sinusitis
   2. Sinus XRay
2. Epidemiology
   1. High False Positive Rate
      1. Upper Respiratory Infection: 85% with CT changes
      2. Asymptomatic adults: 40% with CT changes
   2. References
      1. Gwaltney (1994) N Engl J Med 330:25-30 [PubMed]
      2. Havas (1988) Arch Otolaryngol Head Neck Surg 114:856 [PubMed]
3. Advantages
   1. Much more sensitive than Sinus XRay
   2. Good Sinus Anatomy definition
      1. Views sphenoid and Ethmoid Sinuses well
      2. Defines osteomeatal complex well
4. Indications
   1. Confusing presentation
   2. Evaluation before endoscopic surgery
   3. Sinusitis refractory to maximal medical management
      1. Recurrent Acute Sinusitis
      2. Persistent Chronic Sinusitis Symptoms
      3. Suspected Osteomeatal complex Occlusion
      4. Suspected Allergic Fungal Sinusitis
      5. Suspected Fungal Sinusitis or other complicated Sinusitis (e.g. Immunocompromised patients)
      6. Sinusitis complications (e.g. Cavernous Sinus Thrombosis)
5. Technique
   1. Full Coronal non-contrast Sinus CT
      1. Standard view indicated in most cases
      2. Mucosal thickening >5mm is consistent with sinus infection
      3. Demonstrates fluid and mucosal edema, as well as bony destruction
      4. Fat stranding (increased density) may be present in para-sinus spaces
   2. Limited Sinus CT
      1. Consider as alternative to full Sinus CT
      2. Four non-contiguous 5 mm slices in coronal plane
         1. Frontal Sinus
         2. Anterior ethmoid and Maxillary Sinuses
         3. Posterior ethmoid and Maxillary Sinuses
         4. Sphenoid Sinus
      3. Advantages
         1. Less expensive
         2. Less radiation
      4. Disadvantage
         1. Unknown efficacy
   3. Contrast Sinus CT
      1. Indications
         1. Periorbital Cellulitis or abscess
         2. Vascular complications
         3. Cavernous Sinus Thrombosis
      2. Findings
         1. Necrotic tissue and fluid does not contrast enhance
         2. Inflamed, thickened mucosa contrast enhances
            1. Mucosa, fluid and soft tissue may be indistinguishable without contrast
         3. Consider IV contrast in complicated cases (e.g. vascular complications, Cavernous Sinus Thrombosis)
6. Timing
   1. Perform during maximal medical therapy
   2. Delay if URI present
7. Contraindications: Relative
   1. Submaximal medical Management
   2. Upper Respiratory Infection
   3. Acute sinus infection
8. Interpretation
   1. Findings consistent with Rhinosinusitis
      1. Air-fluid levels
      2. Total opacification
      3. Mucosal thickening >5 mm
   2. Complications identified by Sinus CT
      1. Osteomeatal Complex Obstruction
      2. Allergic Fungal Sinusitis
9. References
   1. Broder (2018) Crit Dec Emerg Med 32(10): 12-3
   2. Mukherji (1998) Radiology 207:417-22 [PubMed]
   3. Okuyemi (2002) Am Fam Physician 66:1882-6 [PubMed]