Integrated Multipoint-Laser Endoscopic Airway Measurements by Transoral Approach

Estimation of Nasal Airway Cross-sectional Area From Endoscopy Using Depth Maps: A Proof-of-Concept Study

OBJECTIVE

Endoscopy is routinely used to diagnose obstructive airway diseases. Currently, endoscopy is only a visualization technique and does not allow quantification of airspace cross-sectional areas (CSAs). This pilot study tested the hypothesis that CSAs can be accurately estimated from depth maps created from virtual endoscopy videos.

STUDY DESIGN

Cross-sectional.

SETTING

Academic tertiary medical center.

METHODS

Virtual endoscopy and depth map videos of the nasal cavity were digitally created based on anatomically accurate three-dimensional (3D) models built from computed tomography scans of 30 subjects. A software tool was developed to outline the airway perimeter and estimate the airspace CSA from the depth maps. Two otolaryngologists used the software tool to estimate the nasopharynx CSA and the nasal valve minimal CSA (mCSA) in the left and right nasal cavities. Model validation statistics were performed.

RESULTS

Nasopharynx CSA had a median percent error of 3.7% to 4.6% when compared to the true values measured in the 3D models. Nasal valve mCSA had a median percent error of 22.7% to 33.6% relative to the true values. Raters successfully used the software tool to identify subjects with nasal valve stenosis (ie, mCSA < 0.20 cm2) with a sensitivity of 83.3%, specificity ≥ 90.7%, and classification accuracy ≥ 90.0%. Interrater and intrarater agreements were high.

CONCLUSION

This study demonstrates that airway CSAs in 3D models can be accurately estimated from depth maps. The development of artificial intelligence algorithms to compute depth maps may soon allow the quantification of airspace CSAs from clinical endoscopies.

Quantitative Measurements in Otological Surgery: Use of an Endoscopic Integrated Multipoint Laser System

OBJECTIVES

Assess the clinical utility of an Endoscopic Integrated Multipoint Laser System (EMLS) to otology. This is an emerging technology from automotive engineering that may offer the ability to accurately measure anatomy and pathology using an endoscope while undertaking ear surgery.

PATIENTS

Simulated otology patients were used incorporating the Phacon Temporal Bone synthetic models and Kyoto Kagaku Ear Examination Simulator models to allow assessment of the EMLS technology in evaluating external ear and middle ear pathology, e.g., perforation or prosthesis sizing.

INTERVENTION

Eight otolaryngology resident and fellows at a tertiary university teaching hospital were given training in EMLS and reviewed simulated anatomy and pathology within the models including tympanic membrane perforation, ossicular discontinuity, and a cochleostomy.

MAIN OUTCOME MEASURE

Variance in measurement was assessed in relation to those made manually by an independent surgeon using surgical calipers (0.1 mm).

RESULTS

The 8 participants produced 47 mean measurements. The mean difference from independently made manual measurement was 0.294 mm (standard error of the mean 0.033). Maximum variance was 0.98 mm and minimum 0.01 mm.

CONCLUSION

Use of an integrated endoscopic laser measurement tool allows reliable, easy-to-obtain measurements to be obtained within a simulated otological surgical environment. Translation of the technology to a thinner delivery system through a rigid endoscope offers further promise for routine use in a clinical setting.

A Simple Endoscopic Technique for Measuring the Cross-Sectional Area of the Upper Airway in a Rabbit Model

OBJECTIVE

Validate an accurate and reproducible method of measuring the cross-sectional area (CSA) of the upper airway.

SUBJECTS AND METHODS

This is a prospective animal study done at a tertiary care medical treatment facility. Control images were obtained using endotracheal tubes of varying sizes. In vivo images were obtained from various timepoints of a concurrent study on subglottic stenosis. Using a 0° rod telescope, an instrument was placed at the level of interest, and a photo was obtained. Three independent and blinded raters then measured the CSA of the narrowest portion of the airway using open source image analysis software.

RESULTS

Each blinded rater measured the CSA of 79 photos. The t testing to assess for accuracy showed no difference between measured and known CSAs of the control images ( P = .86), with an average error of 1.5% (SD = 5.5%). All intraclass correlation (ICC) values for intrarater agreement showed excellent agreement (ICC > .75). Interrater reliability among all raters in control (ICC = .975; 95% CI, .817-.995) and in vivo (ICC = .846;, 95% CI, .780-.896) images showed excellent agreement.

CONCLUSIONS

We validate a simple, accurate, and reproducible method of measuring the CSA of the airway that can be used in a clinical or research setting.

The larynx ruler to measure height and profile of vocal folds: a proof of concept

INTRODUCTION

Glottic leakage during phonation is a direct consequence of unilateral vocal fold (VF) paralysis. This air leakage can be in the horizontal plane and in the vertical plane. Presently, there is no easily applicable medical device allowing noninvasive, office-based measurement of the relative vertical position of the VFs. The larynx ruler (LR) is a laser-based measuring device that could meet the previously stated need, using a flexible endoscope. This study represents a proof of concept regarding the use of the LR in assessing VF relative positions in the vertical plane.

MATERIALS AND METHODS

One fresh male human cadaver larynx, free of neurologic and anatomic disease, was explored with the LR system through the operative channel of a flexible gastroenterology video-endoscope. The tip of the video-endoscope was located in the laryngeal vestibule. The right crico-arytenoid joint was posteriorly disarticulated. Tilting of the VF was obtained by pulling or pushing the arytenoid cartilage with a mosquito forceps fixed to the stump of the previously sectioned superior tip of the posterior crico-arytenoid muscle allowing anterior and posterior tilting of the arytenoid cartilage in order to induce an elevation or a depression of the VF process. Ten "push" and ten "pull" sessions were performed. The distance from the tip of the video-endoscope to each illuminated pixel of the laser beam was recorded. The level difference between the left and right VFs was measured for each recording.

RESULTS

Data provided by the LR were consistently in accordance with the movements applied on the VFs. The accuracy of 0.2 mm of the LR is compatible with the envisioned applications for the human larynx.

CONCLUSION

The LR system represents a feasible technique to evaluate respective vertical position of VFs in the human larynx. Technical limitations were identified that will require improvements before experimental use on human beings.