Comparison of sonography and computed tomography as imaging tools for assessment of airway structures

The aim of this study was to compare airway anatomic parameters as measured by sonography and computed tomography (CT).

Fifteen adult patients underwent CT followed by sonography of the anterior neck under standard conditions. A radiologist and an anesthesiologist with experience in airway imaging examined the scans and performed measurements of specific airway parameters: distance to the posterior surface of the tongue, thickness of the submental region, hyomental distance, depth of the epiglottis from skin (above and below the hyoid bone), thyrohyoid distance, depth of the arytenoid cartilage from skin, and fat pad thickness at the thyroid cartilage. After performing the measurements, they compared the images by the two modalities for descriptions of the structures. Means and SDs were calculated for the measurements, and a paired t test was performed to determine statistically significant differences in the measurements by sonography and CT.

The means of all parameters were closely related except hyomental distance (sonography, 5.23 ± 0.58 cm; CT, 3.50 ± 0.42 cm). The paired t test showed that the mean values for depth of the epiglottis below the hyoid (3.89 versus 4.17 cm; P = .31), thyrohyoid distance (1.03 versus 1.02 cm; P = .95), and depth of the arytenoid cartilage (2.90 versus 2.66 cm; P = .21) were not significantly different as measured by sonography and CT, respectively.

The study shows that sonography can reliably image all of the structures visualized by CT, and in general, infrahyoid parameters agree well between the two modalities, as opposed to suprahyoid parameters, which may be affected by unintentional head extension.