Evaluation of volume of airway using CBCT

·         The CBCT findings that will be analyzed includes the total length of the upper airway, the total airway volume of the oropharyngeal region, the average airway volume of the oropharyngeal region, and the smallest width and anteroposterior (AP) measurements.

·         The oropharynx region will be isolated and analyzed using manual segmentation of each axial slice

·         Using sagittal sections, the total length of the upper airway will be gathered by measuring the length between the lowest border of the C2 vertebra and the posterior nasal spine (PNS).

·         Total airway volume will be obtained through a 3-dimensional volumetric analysis of the upper respiratory tract obtained by tracing a curved line joining dots placed in the middle of the airway at each axial slice.

·         The average airway volume will be automatically generated by the software by dividing the total airway volume by the number of axial slice segmentations.

·         The narrowest area of the airway will be determined by dragging a cursor along the curved line to check the average area at each section.

·         The corresponding location will be viewed in an axial slice to obtain the upper airway’s smallest width and AP measurements.

Evaluation of soft palate using CBCT

·         The critical ratio between soft palate length (VL) and nasopharyngeal depth (PD), known as Need’s ratio (NR), is used to ascertain velopharyngeal incompetency (VPI)^.[13]

·         The VL will be measured as a linear distance from the posterior nasal spine (PNS) to the tip of the uvula of the resting soft palate.

·         The thickest section of velum is known as velar width (VW).

·         The PD was taken as a linear measurement from the PNS to the posterior pharyngeal wall along the palatal plane. The NR will be calculated for all the subjects by dividing the PD with VL