Acoustic rhinometry and paranasal cavities: a systematic study in box models

Acoustic rhinometry (AR) is a well-established diagnostic tool in rhinology. The aim of the study was to test the hypothesis that the paranasal sinuses are a main cause for inaccuracy of AR in the posterior part of the nose.

Experimental study to evaluate the influence of simulated paranasal sinus volume and of the contralateral side of the nose on AR measurements in "box models."

Models were measured with paranasal sinus volume simulated between 0 and 25 mL and with the junction between the models and the paranasal sinuses varying in length and diameter.

Moderate but distinct modification of the posterior area-distance curve was found within the models after changing size of the paranasal sinuses and its junction to the cavity. The apparent cross-sectional area (CSA) measured in the posterior cavum decreased with the volume of the paranasal sinuses. This effect was limited by the length and the diameter of the paranasal junction, as well as by the concha. No influence of the contralateral side on AR measurements was seen.

Acoustic rhinometry reveals reproducible measurements up to 4 cm from the nostril that correspond with the actual model CSA. Simulated paranasal sinuses appear to partially contribute to the inaccuracy in the posterior part of the area-distance curve.