Investigating the three-dimensional morphology of the upper airway using computed tomography

Abstract

The human upper airway is an anatomical region of vital physiological and clinical import. It comprises the nose, paranasal sinuses, pharynx and laryngeal airspaces, which form a continuous and diverse array of geometries ranging from simple tubes to labyrinthine passages. While the upper airway’s general anatomy has long been understood, its morphological variation is less clear. This project aimed to investigate the morphological variation of the human upper airway, specifically of the nasal portion. An archive of 104 computed tomography scans of adult heads was reviewed and the upper airways digitally isolated out to produce three-dimensional models. Statistical shape modelling using principal component analysis was then undertaken on 25 of the airway models. The principal component analysis was limited to the nasal airway, i.e. from the anterior nares through to the nasopharynx, excluding the paranasal sinuses. The nasal airway was found to significantly vary in its morphology across 3 different modes. Firstly, in its general size, scaled in terms of the anterior-posterior and superiorinferior axes. Secondly, in its height, in terms of the superior-inferior axis only. Thirdly, in terms of its superior-inferior curvature. After these three modes the morphological variation of the airway was minimal and insignificant. This study confirms principal component analysis as a practicable method for investigation of three-dimensional anatomical shape variation and provides further insights into how upper airway morphology differs between individuals. Knowledge of this morphological variation may be useful clinically and have applications for future computational modelling or educational purposes.