Test-retest reliability of computed tomography in the assessment of chronic rhinosinusitis

Computed tomography (CT) of the paranasal sinuses has emerged as the standard test for the assessment of chronic rhinosinusitis, as evidenced by the emergence of several CT-based staging systems. Despite its central role in the diagnosis and treatment planning for chronic rhinosinusitis, the sinus CT represents a "snapshot in time." This study was conducted to determine the reliability of the CT scan for chronic sinus disease: are the CT findings in chronic rhinosinusitis stable over time?

A prospective series of patients scheduled for endoscopic sinus surgery was evaluated. A total of 45 patients received two CT scans: an initial scan obtained during routine diagnostic evaluation, and a second scan performed for use as part of an image-guided sinus surgery protocol. No surgical intervention occurred between scans. The patients' scans were staged according to the Lund system by a blinded observer. The correlation between scans for each patient was determined using the matched pairs t test and the Pearson correlation coefficient.

The mean time interval between scans was 122.6 days (range, 5364 d). The average Lund scores for the initial and second scans were 13.56 and 13.27, respectively. The Lund score for 5 patients remained the same, increased in 22 patients, and decreased in 18 patients. Overall, 75.6% of patients' second scans were within +/-2 points of the first scan Lund score. The mean change in score between scans of -0.29 was not significant (P = .606, paired samples t test). The Pearson correlation coefficient between scans was 0.796 (P < .0001).

CT scan assessment of chronic rhinosinusitis is a reliable test. The CT findings in patients with chronic rhinosinusitis remain consistent over time.