Paranasal sinus opacification-to-pneumatization ratio applied as a rapid and validated clinician assessment

The utility of clinician-applied instruments, particularly the Lund-Mackay score, in the assessment of paranasal sinus computed tomography (CT) in chronic rhinosinusitis (CRS) remains incompletely defined. The purpose of this study was to determine if a new approach to the evaluation of sinus CT could accurately predict the extent of opacification while remaining simple for clinician use.

Twenty-four sinus CT scans were measured for the percent of sinus opacification using three-dimensional (3D) volumetric analyses. The same scans were also evaluated using the Lund-Mackay score to measure opacification and the Assessment of Pneumatization of the Paranasal Sinuses (APPS) score to measure total sinus volume (TSV). Correlation analysis was performed for the Lund-Mackay to APPS score ratio as a predictor of percent opacification. Validation analysis was also performed to determine the optimal orientation for Lund-Mackay scoring, which has not previously been described.

The Lund-Mackay to APPS score ratio was very strongly correlated with the percentage of sinus opacification measured by 3D volumetric analysis (r = 0.862, r² = 0.743, p < 0.001). Lund-Mackay scoring was not statistically different between axial-only, coronal-only, or triplanar groups for interrater (p = 0.379) and intrarater reliability (p = 0.312).

The Lund-Mackay score is validated for rater reliability in multiple orientations. Using the APPS score as a measure of TSV, the Lund-Mackay-to-APPS ratio very strongly correlates with the percentage of sinus opacification by 3D volumetric analysis. Further study will be required to determine if this ratio is predictive of symptom severity.