# Agreement Between Acoustic Rhinometry and Computed Tomography Nasal Cross-Sectional Areas Perpendicular to the Direction of the Airflow

## TL;DR

This study compares acoustic rhinometry with CT scans to measure nasal cross-sectional areas and finds that acoustic rhinometry underestimates nasal area by about 15%.

## Contribution

The study provides a detailed comparison of AR and CT measurements in nasal anatomy, identifying specific regions of agreement and discrepancy.

## Key findings

- Acoustic rhinometry underestimates nasal cross-sectional areas by approximately 15%.
- AR-MCA1 and AR-MCA2 correspond closely to CT-CSA at the nasal valve and incisive canal, respectively.
- Correlation between AR and CT measurements was moderate, with stronger agreement at the nasal valve than at the incisive canal.

## Abstract

Background/Objectives: To thoroughly compare acoustic rhinometry (AR) with computed tomography (CT) cross-sectional areas that are approximately perpendicular to the direction of the nasal airflow (CT-CSA). Methods: We retrospectively examined subjects scheduled for functional nasal surgery, along with preoperative CT and AR. CT-CSAs were assessed in several nasal planes in the first 5 cm of the nasal airway. Area sizes and distances of the CT-CSAs from the columella served to create a CT curve analogous to the AR curve. AR curves were digitized. We examined the correlation and agreement (using the Bland–Altman method) between CT curves and digitized AR curves, as well as between selected CT-CSAs and the first two-encountered AR minimal cross-sectional areas (AR-MCA1 and AR-MCA2). Correlation was investigated by univariate analysis of variance and Pearson’s correlation. Agreement was examined by the Bland–Altman method. Results: In 33 subjects, the correlation of digitized AR with CT was moderate (r = 0.76; p < 0.001). AR, in general, underestimated the actual nasal area by 15%. AR-MCA1 and AR-MCA2 were closest to the CT-CSA of the nasal valve and the incisive canal, respectively. We noted a mainly moderate correlation between the CT-CSA of the nasal valve and AR-MCA1 (all r > 0.59; all p < 0.001) in contrast to the weaker correlations between the CT-CSA of the incisive canal and AR-MCA2. Conclusions: AR may underestimate the actual nasal area by 15%. AR-MCA1 and AR-MCA2 were closest to the CT-CSA of the nasal valve and the incisive canal, respectively.