Background: Chronic rhinosinusitis (CRS) may occur through heterogeneous disease processes. It is possible that more than 1 inflammatory process underlies CRS in any given patient. If so, heterogeneity in processes may be a function of the spatial organization of the paranasal sinuses. Density characteristics of sinus opacities on computed tomography (CT) scans offer insight into the nature of sinus opacities and disease, in general, and may thus be used to detect spatial heterogeneity of sinus disease within a given patient.
Methods: The study was a retrospective chart review of CRS patients with available sinus CT scans. Radiographic density profiles of sinus opacities were assessed by raw measures of densities (in Hounsfield units [HU]). Radiographic density profiles of the different affected sinuses were compared to each other, checked for correlation, and finally, checked for evidence of clustering using a principal component analysis.
Results: Frontal sinus opacities appear to be more heterogeneous, with both higher and lower density components than other sinuses. There was strong correlation between the radiographic density profiles of opacities in the frontal, anterior ethmoid, and sphenoid sinuses (p < 0.001). However, on principal component analysis the radiographic density characteristics of the opacities of the frontal and anterior ethmoid sinuses appeared to cluster together more than the other sinuses.
Conclusion: Radiographic properties of sinus opacities suggest the nature of sinus opacities are related not only to some common underlying pathology but also to factors related to the specific sinus as well as other spatially close affected sinuses. This suggests an anatomic orientation for sinus pathophysiology in CRS.
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