Endoscopic imaging of the human laryngeal complex in an experimental setting - methodology and clinical significance

Abstract

AIM: The human laryngeal complex has been an endoscopic sight since the late 19th century, however despite the technological advances little has changed in the standard observational methodology, with optical distortion of the image being a major setback in all endoscopic studies. The aim of this study is to evaluate different endoscopes and image correction algorithms in the endoscopic imaging of the laryngeal complex. METHODS AND MATERIALS: Conventional rigid 00, 300, 700 and 900 endoscopes and a flexible otorhinolaryngoscope with two-dimensional imaging capabilities, a digital camera and a direct laryngoscope were used together with an intubation mannequin to obtain endoscopic images of the laryngeal complex. Images of a custom made lens distortion grid were taken to compare the different optical systems and used as a benchmark for image correction. Both sets of images were superimposed in order to digitally correct for angle and lens distortion and to show the true size and proportions of the human laryngeal complex, so far seen only during an intubation or autopsy. RESULTS: After comparing the fiber optic and rigid endoscope obtained images, the rigid endoscopes proved to have better imaging qualities and therefore a better potential for future in depth study of laryngeal anatomy. The rigid 700 endoscope, compared to other rigid systems, allowed for an atraumatic perpendicular to the glottis view of the laryngeal complex, best suited for the study, despite the higher image distortion. CONCLUSION: Based on the collected data the 700 rigid otorhinolaryngoscope together with a standard software correction is an affordable, atraumatic and reliable method for anatomical and proportionate measuring of the human laryngeal complex in a model study.