Which radiological finding on CT paranasal sinuses is diagnostic of chronic rhinosinusitis according to the Lund-Mackay staging system?

Explanation

## Lund-Mackay CT Staging System for Chronic Rhinosinusitis ### Definition and Diagnostic Criteria **Key Point:** The Lund-Mackay system is the gold standard CT scoring method for chronic rhinosinusitis (CRS). Opacification of at least one sinus cavity (partial or complete) is the core radiological finding that supports a diagnosis of CRS when combined with clinical symptoms lasting ≥12 weeks. ### Lund-Mackay Scoring System | Finding | Score | |---------|-------| | **Ostiomeatal complex** | 0 = patent; 2 = obstructed | | **Each maxillary sinus** | 0 = clear; 1 = partial opacification; 2 = complete opacification | | **Each anterior ethmoid** | 0 = clear; 1 = partial opacification; 2 = complete opacification | | **Each posterior ethmoid** | 0 = clear; 1 = partial opacification; 2 = complete opacification | | **Sphenoid sinus** | 0 = clear; 1 = partial opacification; 2 = complete opacification | | **Frontal sinus** | 0 = clear; 1 = partial opacification; 2 = complete opacification | | **Maximum total score** | 24 (bilateral) | ### Diagnostic Interpretation **High-Yield:** CRS is diagnosed when: 1. **Clinical criteria:** Symptoms (nasal obstruction, rhinorrhea, facial pain/pressure, anosmia) for ≥12 weeks, AND 2. **Radiological criteria:** CT evidence of sinus opacification (partial or complete) in at least one sinus cavity. **Clinical Pearl:** Mucosal thickening alone (<4 mm) is a non-specific finding and does not meet diagnostic criteria for CRS. Opacification (air replaced by fluid or soft tissue) is the key finding. ### What Each Score Means - **Score 0–5:** Mild CRS or incidental findings - **Score 6–12:** Moderate CRS - **Score 13–24:** Severe CRS (often warrants surgical consideration) **Mnemonic:** **OASES** — *Ostiomeatal complex, Anterior ethmoid, Sphenoid, Ethmoid (posterior), Sinuses (maxillary/frontal)* — the anatomical regions scored in Lund-Mackay.