BACKGROUND: Computed tomography (CT) of the sinuses is the standard assessment for sinus mucosal disease but is criticized for lack of specificity. Data regarding the correlation between sinus CT findings and histopathology are lacking. The objective of this study is to determine whether the degree of radiologic change noted on CT correlates to the severity of histopathologic changes in a robust, reproducible rabbit model of rhinosinusitis.
METHODS: Six (unilateral) sinuses in 6 rabbits were directly inoculated with Pseudomonas aeruginosa (n=3) or Staphylococcus aureus (n=3) for 1 week, and ostia blocked with a sponge. Contralateral sinuses served as internal controls. Sponges were removed at 1 week, and animals were evaluated 3 weeks later with CT scan (Kerschner’s grading system) and histopathology (epithelial (E)/submucosal (SM) thickness).
RESULTS: CT scores and E/SM thickness were significantly higher in the infected sinuses compared to the contralateral sinuses (CT: 6.96+/-1.3 vs 0.0+/-0.0, E thickness (µm): 37.77+/-5.87 vs 16.0+/-3.33, SM thickness (µm): 204.2+/-21.74 vs 78.75+/-14.73). CT scores and E/SM depth were strongly correlated (CT vs E depth: r=0.76, p<0.01, CT vs SM depth: r=0.92, p<0.0001). Regression analysis demonstrated that SM thickness significantly affected CT scores compared to E thickness (p < 0.0001). Inflammation in the epithelial layer was noted in the contralateral sinuses despite a lack of CT findings.
CONCLUSION: Findings suggest that the severity of sinus disease based upon CT correlates to the degree of histopathologic disease in this rabbit model of rhinosinusitis. CT findings likely represent changes to the submucosal layer of the inflamed sinus.