Dynamic B-mode ultrasound imaging of vocal fold vibration during phonation.

We used B-mode imaging to study the vibratory phenomena of the vocal folds. The presence of multilayered structures of the vocal folds in the B-mode image was verified by using freshly excised human larynges in vitro. To capture images of vocal fold vibration, a special treatment was used to reconstruct the aliasing B-mode motion pictures of vocal fold vibration. Echo-particle image velocimetry (Echo-PIV) analysis was then applied to trace the tissue particles in the motion pictures. The vibratory behavior of the body (vocal ligament and muscle) of the vocal folds was revealed. Further analysis showed a quasi-longitudinal wave along the body of the vocal folds in the coronal plane. This is, to the best of our knowledge, the first time that vocal fold vibration physiology has been studied using B-mode imaging and Echo-PIV.