A New Method for Anterior Boundary Demarcation of the Nasopharynx in Three-Dimensional Analysis

Three-dimensional (3D) measurements of the upper airway have been extensively applied and researched, but the division of the airway is carried out in various ways, especially when demarcating the anterior boundary of the nasopharynx. The present study was to propose a new method based on the anatomical definition for the anterior boundary demarcation of the nasopharynx used in three-dimensional analysis. Twenty computed tomography scans (age 9.5 +/- 2.5 years, 11 males, and 9 females) of head and neck were randomly selected and transferred to Materialism's interactive medical image control system 19.0 for segmentation of the nasopharynx. Precise localization of the reference points that determining the nasopharyngeal anterior and inferior boundaries was managed by recording their coordinates in the interface of the software. The area of the anterior and the inferior boundaries, and the volume of the nasopharynx were measured and repeated with a 2-week interval for the consistency test. Both the interobserver reliability as well as the intra-observer reliability were very high (intraclass correlation coefficients, 0.985-0.997). Paired t test showed no significant difference between the first and the second examinations. This new simple method proposed for demarcation of the nasopharyngeal anterior boundary was based on the innate anatomical boundary, which was statistically reliable, technically convenient, and clinically reasonable.