Anatomic correlates of acoustic rhinometry as measured by rigid nasal endoscopy

Acoustic rhinometry (AR) evaluates the cross-sectional areas and volume of the nasal cavity through acoustic reflections. Successive valleys displayed on an AR graph are believed to correspond to anatomic landmarks. To assess the anatomic accuracy of AR, we performed AR and endoscopic measurements with a rigid endoscope in 85 normal human subjects after topical decongestion. Endoscopic measurements were recorded for distances between the midcolumella and the nasal valve, the anterior end of the inferior turbinate, the anterior end of the middle turbinate, the midportion of the middle turbinate, and the posterior nasopharynx. The first AR valley most closely corresponded with endoscopic measurements of the nasal valve. The second valley had a mean value that corresponded with the anterior end of the inferior turbinate. The third valley matched best with the values of the anterior end of the middle turbinate. Nasopharyngeal measurements by each modality yielded a good agreement. AR appears to correspond to nasal anatomic landmarks but not in an exact point-to-point manner.