CT analysis of the anterior nasal airway based on the direction of nasal airflow in patients with nasal obstruction and trauma controls

Purpose The anterior nose is the nasal segment with the highest resistance to airflow. In a hospital-based case–control study, we compared cross-sectional areas of the nasal cavities anterior to the piriform aperture determined by computed tomography (CT-CSA) in patients with nasal obstruction (cases) and unselected patients with trauma unrelated to the head and face (controls). Methods CT-CSA could be reproducibly identified at angles of 0 o , 30°, 60°, and 90° to the nasal floor approximately perpendicular to the arcuate direction of nasal airflow using bony landmarks. CT-CSA were manually segmented and compared in cases and controls. In cases, we compared CT-CSA at 30° (CT-CSA 30-narrow ) with the minimum cross-sectional area determined by acoustic rhinometry (AR-MCA 1-narrow ), each on the narrower side. Results CT-CSA ranged from 7 to 250 mm 2 with an average of 100 mm 2 per nasal side. Side differences of the nasal airways indicating asymmetry of the nasal airways were greater in 40 cases than in 44 controls ( p < 0.003). Moreover, bilateral CT-CSA were significantly smaller in cases than in controls ( p < 0.001). CT-CSA 30-narrow did not significantly correlate with AR-MCA 1-narrow ( r = 0.33; p = 0.07) and on average was 58% smaller than AR-MCA 1-narrow . Conclusions Cross-sectional areas of the anterior nose perpendicular to the direction of nasal airflow, which is considered relevant in terms of flow physics, can be reliably measured using CT. Anterior nasal cavities in patients with nasal obstruction were more asymmetric and, as a whole, narrower than in controls, the latter of which is not corrected by routine septoplasty.