Quantifying Vocal Fold Vibration in the Coronal Plane Using Optical Coherence Tomography in Normal Human Subjects

Assessment of human vocal fold (VF) morphology and vibration is largely limited to surface visualization via laryngeal videostroboscopy. Using optical coherence tomography (OCT), this study aims to measure VF vibratory dynamics in the coronal plane of healthy volunteers to support a quantitative assessment of VF biomechanics.

Cross-sectional observational pilot study METHODS: Twelve healthy participants underwent awake, transoral imaging using a custom-built, hand-held rigid laryngoscope equipped with OCT technology. Phonation was captured during sustained vowel /i/ production at a modal pitch and loudness. A novel algorithm was utilized to reconstruct the phase-resolved VF vibratory cycle during phonation from the OCT data. Seven dynamic metrics were extracted from each video reconstruction, including closed quotient (CQ), angle at closure (AaC), divergent phase vertical thickness (DPVT), closed phase vertical span (CPVS), mucosal peak, amplitude of lateral excursion (amplitude), and vertical phase difference (VPD). Data were grouped by gender, and applicable metrics were stratified into right vocal fold and left vocal fold regions. Independent t-tests were performed to assess gender and laterality differences for each metric. Pairwise Bonferroni-adjusted Pearson correlations were performed between metrics.

Seven novel metrics were successfully extracted and measured from OCT data in all subjects. Significant gender differences were found for DPVT (p = 0.015), amplitude (p = 0.049), and VPD (p = 0.043). No significant laterality differences were observed except for DPVT in the female group. Correlation analyses showed a positive correlation between DPVT and CPVS (r = +0.89). CQ was negatively correlated with AaC (r = -0.74) and positively correlated with VPD (r = +0.83) CONCLUSION: OCT imaging of the VFs can be successfully performed in normal subjects during phonation to visualize sub-surface VF anatomy and vibration, enabling quantitative characterization of VF dynamics.