Objective:
Dynamic CT was used to quantify vocal fold motion characteristics, including cartilage movement and soft tissue changes during inspiration and phonation.
Method:
Dynamic CT scans were performed on five subjects who had verified normal voices by a trained voice doctor. CT scans were taken of the subjects' larynx during the inspiratory and phonation/i:/process to obtain 10 time phases during a 5 second scan. Cartilage and soft tissue laryngeal 3D models were segmented and reconstructed for each of the 10 time phases using Materialise Mimics software. The cartilage 3D models and the vocal fold 3D models were divided into the inspiratory phase and the phonatory phase, in which the rotation angles of the arytenoid cartilage on the cricoid cartilage, the anterior and posterior displacement of the arytenoid cartilage, and the length of the vocal fold were measured. Rotation about the longitudinal axis, sagittal axis, and horizontal axis were defined as roll, pitch, and yaw respectively.
Results:
The yaw angle of the arytenoid cartilage is statistically significant between the inspiratory phase and the phonation phase, there was no significant difference in the distance between the upper margin of the cricoid cartilage and arytenoid cartilage muscular process or in the distance between the upper margin of the cricoid cartilage and arytenoid cartilage muscular process, between the inspiratory and the phonation phases. However, there was significant difference in the length of the vocal folds between the inspiratory phase and the phonation phase.
Conclusion:
Dynamic CT with three-dimensional reconstruction has proven to be a successful method for noninvasively visualizing and quantifying a variety of dynamic characteristics of vocal fold motion.
