The Clinical Feasibility of Functional 3-Dimensional Laryngeal CT as a New Technique: Preliminary Study in Unilateral Vocal Fold Paralysis

Jun, Beom Cho; Kim, Hyung Tae; Choe, Hyeog Gi; Kim, Hyun Su; Cho, Kwang Jae; Park, Young Hak; Kim, Min Sik; Cho, Seung Ho

Abstract

BACKGROUND AND OBJECTIVES
There are many clinical procedures that are related to the evaluation of kinematic events concerning vocal fold vibration. However, many of these procedures are hardly applicable for precise analyses of physiological and morphological changes in vocal folds with respect to the pitch control, and vocal fold volume changes from the phonatory aspect of larynx. The purpose of this study was to examine the clinical feasibility of a new 3 dimensional image method, the functional laryngeal CT, which can provide a clear sagittal image of the vocal fold in each of the anteroposterior directions during phonation and resting state. SUBJECTS AND METHOD: Functional laryngeal CT was performed in 4 normal control and 2 cases of unilateral vocal fold paralysis. The subjects were instructed at resting position to produce sustained vowel phonation of three different kinds of pitch. Three-dimensional endoscopic images were reconstructed through segmentation and surface-rendering algorithm on personal computer, using the DICOM (Digital Image and Communication in Medicine) file of axial images. RESULTS: The dynamic vocal fold 3D image that was reconstructed by serial section image during phonation showed that the vocal fold became thin and volume was decreased in relation to the increase in pitch. Typical subglottic shoulder formation and ventricular widening was noted in the high pitched tone. CONCLUSION: Functional 3D laryngeal CT (F3DLxCT) is an informative tool for visualizing the active changes in length, tension and mass of the vocal folds for pitch control. Furthermore, the volume defect and the level difference in the paralysed vocal fold are easily detectable with this new techinque.