Nasal airway geometry: comparison between acoustic reflections and magnetic resonance scanning

Abstract

To evaluate the accuracy of the acoustic reflection (AR) technique for determination of nasal cavity cross-sectional areas, the area-distance function of both sides of the nose was determined in 10 subjects and compared with magnetic resonance imaging (MRI). Interindividual variation for the correlation between MRI and AR was seen, but in general the areas from 1 to 6 cm into the nasal cavity measured by AR were larger than areas measured by MRI, especially where the surface was most convoluted. The total volume for this region was 6.47 +/- 1.83 (SD) cm3 for AR and 5.65 +/- 1.34 cm3 for MRI. It was demonstrated that this could be due to errors in calculation of the areas on the basis of MRI and AR. In the posterior part of the nasal cavity and the epipharynx, there was a convincingly higher correlation between acoustic measurements and a scan perpendicular to the assumed geometrical axis of the epipharynx than between acoustic measurements and coronal scanning. This indicates that the sound axis roughly follows the geometrical axis. In a model of two tubes (nasal cavities) joined in a larger tube (the epipharynx), closure of the posterior part of the latter revealed that the contralateral nasal cavity is likely to cause overestimation of the posterior part of the epipharynx during AR compared with MRI.

Acoustic rhinometry in dog and cat compared with a fluid-displacement method and magnetic resonance imaging

“…Terheyden et al (26) summarize several attempts to validate how precisely AR measures the nasal cavity in humans, including validation of AR by magnetic resonance (MR) imaging (2,8) and by a fluid-displacement method (FDM) (7). By comparing volumes determined by AR with volumes of nasal cavity casts, Kaise et al (12) found AR in guinea pigs to measure only 75% of nasal cavity volume.…”

Ultrafine and Fine Aerosol Deposition in the Nasal Airways of a 9-Month-Old Girl, a 5-Year-Old Boy and a 53-Year-Old Male

“…Other studies have highlighted the physical significance of transient breathing (Shi et al, 2006), inlet velocity profiles (Keyhani et al, 1995;Subramaniam et al, 1998), nasal wall motion (Fodil et al, 2005), nasal valve change (Bridger 1970;Bridger and Proctor 1970) and glottal aperture variation (Brancatisano et al, 1983;. Moreover, each nasal model in this study is based on images of one single subject and does not account for the intersubject variability (Hilberg et al, 1993;Pickering and Beardsmore 1999). Another limitation is the typical supine position of the subjects during data acquisition, which is different from normal breathing while awake.…”

Die optische Rhinometrie

“…Eine direkte Schwellungserfassung in der Nase ist ebenfalls mit der Computertomographie und der Magnetresonanztomographie [3,8,12] möglich. Hier kön-nen endonasale geometrische Verhältnis-se korrekt abgebildet werden.…”

“…Die Ankopplung des Ultraschalles erfolgt dabei durch Gel oder Flüssigkeit in der Nase. Bewegungsartefakte werden durch eine Bissschiene verhindert [24,25].Eine direkte Schwellungserfassung in der Nase ist ebenfalls mit der Computertomographie und der Magnetresonanztomographie [3,8,12] möglich. Hier kön-nen endonasale geometrische Verhältnis-se korrekt abgebildet werden.…”