Acoustic rhinometry as method for evaluating paranasal sinuses--experimental studies

Abstract

The potential application of acoustic rhinometry for evaluating paranasal sinuses was evaluated experimentally. In order to assess the influence of paranasal sinus volume in acoustic rhinometry, three model studies were performed. A tube made of acryle (20 cm in length, 2 cm in diameter) with a side hole was used for the first experiment. In the experiment measuring this tube with acoustic rhinometry, a difference between cases with a side hole (ex. 2 mm in diameter) and these without a side hole was observed. In the former, a more posterior tube position gave rise to an increase in the acoustic curve. In the second experiment, a syringe was was fixed to the side hole of the tube, so as that no leakage of sound wave would occur. A change in the volume of the syringe could be detected by acoustic rhinometry, even with changes as small as 1 ml. In the third experiment, the relationship between the size of the side hole and the volume of the syringe was evaluated. When the volume was less than 20 ml, the value was almost equal to the theoretical value even if the diameter of the side hole was as small as 4 mm. A larger size hole was required when the volume was increased. It was concluded that acoustic rhinometry is of possible value in assessing the paranasal sinuses, if the nasal cavity communicates with the paranasal sinuses via a large opening (e.g. in post-operative cases).