Dynamic 3D MRI for vocal fold oscillation measurements.

The source of the human voice lies in the rapid oscillations of the vocal folds (VF) inside the larynx. Currently, VF diseases are diagnosed with an endoscope providing a superficial view of the VFs but no further 3D information of the underlying VF structures. With magnetic resonance imaging (MRI) the full 3D spatial information could be acquired, but MRI so far lacks the necessary temporal resolution. We propose a new MRI method based on zero echo time (ZTE)-MRI to encode the rapid periodic VF oscillation. Combined with projection navigators to compensate for laryngeal motion and simultaneous voice recordings we are able to reconstruct the VF oscillation with a temporal resolution of 819μs and a spatial resolution of 0.77 mm. Our technique allows the first dynamic and 3D visualization of the VF oscillations and enables quantification of contact area and vertical displacement throughout the oscillation cycle. From the dynamic data, laryngeal tissue geometries can be extracted, such as the vertical displacement (1.2 mm) or the change in contact area (25.9 mm²) over the oscillation cycle. This non-invasive technique offers a new diagnostic tool for clinicians and for voice production studies.