Quantification of Respiratory Laryngeal Morphometry: Comparison of Laryngeal Lumen Angle Estimate Methods

Objectives: Evaluate the effects of (1) laryngeal configuration, (2) image barrel distortion, and (3) lens perspective on the accuracy of anterior and posterolateral laryngeal lumen angle morphometric estimates.
Study Design: Prospective, repeated-measures.
Methods: Twenty-four (24) excised canine larynges were manipulated across four different length-by-width configurations to evaluate the influence of laryngeal configuration on relative precision of three laryngeal morphometric angle estimate methods. Physical measurements of the laryngeal specimens were compared (statistically and descriptively) with corresponding unadjusted and barrel-distortion corrected laryngoscopic laryngeal images. Additional post hoc analysis involved systematic manipulation of camera lens-to-object perspective (shift, tilt, and distance) using a synthetic object representing the physical laryngeal specimen and simulated image of the laryngoscopic laryngeal images. Morphometric angle estimates between the synthetic object and the simulated images were compared across simulated lens-to-object perspective manipulations to evaluate influences of lens perspective artifacts on laryngeal morphometric estimate precision.
Results: Statistical analysis showed that laryngeal morphometric angle estimates were impervious to laryngeal configuration manipulations, but were influenced by image barrel-correction methods. Statistically significant differences were found between the unadjusted and barrel-corrected images within the anterior angle method. Simulated camera lens-to-object perspective manipulations showed that tilt and distance have substantial negative influence on laryngeal morphometric estimate precision.
Conclusions: Laryngeal lumen angles can be used to measure respiratory laryngeal morphometry. However, image-correction algorithms are necessary to correct images and quantify morphometric estimate error caused by camera lens distortion and lens-to-object perspective. Findings provide a platform for future research on quantifying laryngeal morphometry, especially for individuals with laryngeal breathing disorders.