Ultrafast Dynamic 3-dimensional Magnetic Resonance Imaging of the Vocal Fold Oscillation

• Applicants: Dr. Johannes Fischer; Dr. Louisa Traser
• Subject Area: Medical Physics, Biomedical Technology ; Otolaryngology, Phoniatrics and Audiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525074946

Laryngo-video-stroboscopy is the gold standard in the clinical assessment of the vocal fold (VF) oscillation. However, due to the top down view on the oscillating VFs, this technique is insensitive to their vertical movement as well as the configuration of the glottal channel and VFs medial surface. Motion below the VF plane is entirely hidden. Thus, a visualization of the mucosal wave formation in the coronal plane is still missing. Recently, we have developed a new magnetic resonance imaging (MRI) technique that offers the necessary high temporal resolution well below 1 ms to visualize the VF oscillation in a coronal plane. In the proposed project, we want to improve on our previous work and extend our acquisition scheme to three dimensions to enable full 3D studies of the wave formation for the first time. The 3D technique will be used in a volunteer study, where we want to image different oscillatory modes in professionally trained singers. Initially, the project will measure the relaxation times of VF tissue to optimize the contrast in the subsequent VF imaging studies. Then, a dynamic 3D imaging technique will be developed for volunteer studies using an additional frequency encoding along the slow axis of VF motion. Optimal sequence parameters will be gained from simulations of numerical VF phantoms and preliminary volunteer measurements. During the volunteer study we will use this technique to visualize the VF oscillation in 20 subjects and extract geometric features, such as the VF contact area or its vertical displacement in the oscillation cycle. At the same time, we work on improvements of the measurement setup. Currently, for dynamic VF imaging MR data is gated retrospectively using motion information obtained from electroglottography (EGG), which is acquired simultaneously. To reduce the complexity of the measurement setup, to reduce setup times and to improve patient comfort we aim to replace the EGG electrodes with a microphone that will record the volunteers’ voice during MRI. The fundamental frequency used in the imaging study is linked to the temporal resolution of the MRI technique. Thus, to allow for higher frequencies in future studies, we will also increase the temporal resolution, which currently is limited by peripheral nerve stimulation (PNS). Finally, we will investigate whether radial imaging is a viable alternative. Radial imaging techniques create less acoustic noise and PNS at the expense of temporal resolution. To assess the accuracy of the different measurement techniques we will also use an MR-compatible mechanical VF motion phantom. With the results of this technological development a set of 3D imaging methods for dynamic VF MRI will become available which will allow a fundamentally new in vivo analysis of VF oscillation and thus has the potential increase fundamental knowledge on voice production.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Michael Bock; Professor Dr. Matthias Echternach; Professor Dr. Bernhard Richter