CT-based distribution of paranasal sinus involvement in sinusitis: A retrospective single-centre study

Background Sinusitis is among the most common inflammatory conditions of the paranasal sinuses, and computed tomography (CT) is the reference modality for demonstrating sinus involvement. The maxillary sinus is generally reported as the most frequently affected, but local data from the Eastern Province of Saudi Arabia are limited. This study determined the distribution of CT detected paranasal-sinus involvement and its association with age, sex, and contrast-media hypersensitivity in patients imaged at King Abdulaziz Hospital. Methods In this retrospective cross-sectional study, consecutive patients who underwent paranasal-sinus CT in the Department of Radiology between 1 June 2023 and 1 December 2025 were recorded. Only the first CT per patient was included, yielding 293 patients aged 10-69 years. Sinusitis was defined as CT-reported inflammatory involvement (mucosal thickening, air-fluid level, or opacification) of one or more paranasal sinuses on the finalized radiology report, and the clinical indication for each scan was recorded. The proportion of patients with CT-detected sinus involvement and the sinus-level distribution were analysed separately. Associations were tested with the chi-square or Fisher exact test and the Welch t -test p < 0.05 was considered significant. Results CT-detected sinus involvement was present in 134 of 293 patients (45.7%). Among 219 involved sinuses, the maxillary sinus was most frequently affected (114, 52.1%), followed by the ethmoid (40, 18.3%), frontal (33, 15.1%), and sphenoid (32, 14.6%) sinuses, 78 patients had single-sinus and 55 had multi-sinus involvement. Patients with sinusitis were modestly older than those without (mean 39.0 vs 35.0 years, p = 0.015). No significant difference was found between genders (p = 0.26), and there was no association with contrast-media hypersensitivity (p = 0.56). Conclusion In this single-centre CT cohort, the maxillary sinus was the most commonly involved paranasal sinus. These frequencies reflect a hospital population referred for CT and should not be generalized.