What are the advantages of using Computed Tomography (CT) scans in adult patients with Chronic Rhinosinusitis (CRS)?

Advantages of CT in Chronic Rhinosinusitis

CT imaging provides superior bone detail and soft-tissue visualization in a single multiplanar study, making it the gold standard for confirming CRS diagnosis, identifying anatomical variants that increase surgical risk, and guiding surgical planning when medical therapy fails. 1, 2

Diagnostic Confirmation and Accuracy

CT objectively confirms the diagnosis of CRS by demonstrating mucosal thickening, sinus opacification, polyps, retention cysts, and bony sclerosis—findings that correlate with true disease rather than symptom reporting alone. 3 This is critical because symptoms alone are highly nonspecific; patients with identical CRS symptoms may have completely normal sinus CT scans in up to 40% of cases. 4

• CT has proven test-retest reliability with a Pearson correlation coefficient of 0.796, meaning findings remain stable over time in true CRS (75.6% of repeat scans within ±2 points on Lund-Mackay scoring). 5
• CT is superior to nasal endoscopy for detecting ostiomeatal complex involvement, concha bullosa, paradoxical turbinate, and septal deviation—all critical anatomical factors. 6
• The Lund-Mackay scoring system quantifies disease extent objectively (maximum score 24), providing standardized documentation. 2

Surgical Planning and Risk Reduction

CT is critical for identifying anatomical variants that dramatically increase surgical risk, including structures that predispose to CSF leak, optic nerve injury, carotid artery injury, and orbital penetration. 3

• Multidetector CT without IV contrast identifies sphenoethmoidal (Onodi) cells that place optic nerves and carotid arteries at risk during surgery. 3
• CT delineates cribriform plates, lamina papyracea, and anterior ethmoidal artery canal—structures that must be avoided during functional endoscopic sinus surgery (FESS). 3
• Coronal CT provides excellent anatomic bony detail of the paranasal sinuses, either through thin-slice axial images with multiplanar reformations or direct coronal acquisition. 1
• Multidetector CT allows a single scan with reconstruction in all planes (coronal, sagittal), reducing total radiation exposure compared to older techniques. 1

Extent of Disease Assessment

CT reveals the full extent of disease throughout all sinus cavities, information that cannot be obtained through endoscopy alone, which only visualizes anterior structures. 2

• CT identifies polyps extending outside the nasal cavity, unilateral disease requiring exclusion of neoplasm, and atypical presentations. 2
• CT detects structural abnormalities, masses, and bony erosion that may indicate aggressive pathology mimicking CRS, such as osseous destruction and extrasinus extension. 3
• The radiological pattern on CT can predict atopy: a central "black halo" sign (centrally limited changes in all sinuses) predicts inhalant allergen sensitization with 90.82% specificity. 1

Treatment Decision-Making

CT findings directly alter management by distinguishing patients who need surgery from those requiring continued medical therapy or alternative diagnoses. 7

• Point-of-care CT at initial evaluation prevents unnecessary antibiotic prescriptions: in one study, 0% of CT-negative patients received antibiotics when scanned early, versus 12.5% when treated empirically. 7
• CT performed after failed medical therapy provides the anatomic roadmap necessary to guide FESS, which achieves symptom improvement and quality of life gains in over 75% of patients. 3
• The degree of neo-osteogenesis visible on CT (Kennedy osteitis score 0-3; Global osteitis scoring system 0-5) has important prognostic implications for surgical outcomes. 1

Technical Advantages Over Alternatives

CT has supplanted plain radiographs because conventional sinus radiographs are inaccurate in a high percentage of patients. 1

• Low-dose CT protocols reduce radiation exposure to 0.07 mSv—10 times lower than standard protocols—without compromising anatomical accuracy. 1
• CT is superior to MRI for delineating osseous thinning, infundibular obstruction, and uncinate process lateralization. 3
• Cone beam CT (CBCT) can be obtained in office settings with lower radiation, though it lacks soft-tissue resolution and is not preferred when extrasinus disease is suspected. 3
• IV contrast is generally not needed for CRS evaluation or surgical planning. 1, 3

Common Pitfalls to Avoid

Do not order CT for uncomplicated acute rhinosinusitis lasting less than 4 weeks without complications—this is explicitly not recommended. 1 CT is appropriate only when acute bacterial rhinosinusitis has associated complications including headache, facial swelling, orbital proptosis, or cranial nerve palsies. 1

Do not order CT based on symptoms alone without attempting appropriate medical therapy first, unless complications are suspected. 1 However, early CT may be more cost-effective than extended empiric antibiotic courses and is preferred by patients. 1

Do not assume CT findings correlate with symptom severity—they often do not, except possibly in patients with nasal polyps. 3 Paradoxically, patients with more severe facial pain and headache may have normal CT scans. 4

Obtain objective evidence before prolonged antibiotic therapy: the absence of mucopurulence on endoscopy has 100% specificity for ruling out CT-confirmed CRS, though sensitivity is only 24%. 4 Without CT or endoscopic confirmation, prolonged antibiotics may be inappropriate. 4