Background: Acoustic rhinometry (AR) accuracy in the diagnosis and follow-up of nasal polyps is as yet unclear. Our objective was to study its accuracy compared with computed tomography (CT) in patients with nasal polyps.
Methods: We studied 29 patients diagnosed of nasal polyposis by nasal endoscopy. In all patients sinunasal CT-scan, AR and nasal nitric oxide (NO) were assessed. Nasal volumes between 0 and 5 (V(0-5)) and 5 and 9 (V(5-9)) centimetres from nasal inlet were measured with AR and CT-scan, by using Pearson and intraclass correlation coefficient tests.
Results: All patients (29,79% males, mean age 48.2 yr [range 34-61]) had nasal polyps (score 2-3 on Lildholdt classification, score 0-3). Measurements (right plus left sides) were: AR 8.9 +/- 0.8 cm(3) (V(0-5)) and 15.5 +/- 3.6 cm(3)(V(5-9)); CT 6.5 +/- 0.4 cm(3) (V(0-5)) and 6.3 +/- 0.8 cm(3) (V(5-9)). Pearson correlation was r = 0.67 (p < 0.01) for V(0-5) and r = 0.62 (p < 0.05) for V(5-9). Intraclass correlation coefficient test was 0.51 (V(0-5)) and 0.28 (V(5-9)) for consistency; and 0.43 (V(0-5)) and 0.23 (V(5-9)) for absolute agreement. Low levels of NO (312.3 +/- 43.8 ppb) were found and the correlation between NO levels and volumes (V(0-5) or V(0-9)) measured by AR was not statistically significant.
Conclusions: Compared to CT-scan, AR measurements accurately reflect the geometry of nasal cavity volumes in patients with nasal polyps, with a better assessment in the anterior part of the nasal cavity.