Tobias Frauenrath1, Andreas Goemmel2, Christoph Butenweg2, Mario Otten3, Thoralf Niendorf1,4
1Berlin Ultrahigh Field Facility, Max-Delbrueck Center for Molecular Medicine, Berlin, Germany; 2Chair of Structural Statics and Dynamics, RWTH, Aachen, Germany; 3Erich-Thienhaus-Institute, Hochschule fr Musik, Detmold, Germany; 4Experimental and Clinical Research Center (ECRC), Charit Campus Buch, Humboldt-University, Berlin, Germany
Even if some spatial insight can be obtained by stereoscopy imaging from classical optical methods or ex-vivo experiments, real 3D in-vivo measurements of vocal fold geometry are still elusive. Magnetic resonance imaging (MRI) is conceptually appealing for the pursuit of 3D imaging since it affords sub-millimeter spatial resolution and versatile tissue/muscle/cartilage image contrast. However, MRI comes with the penalty that it requires relatively long scan times. Hence, imaging of moving organs requires consideration of physiological motion. For the phonating vocal folds, periodic oscillation is superimposed by breathing movements (abduction and adduction). While for the first, synchronization cannot be obtained yet, the second can be handled by a customized explicit synchronization technique. The imaging protocol consisted of segmented 3D gradient-echo imaging and segmented 3D ultra-short TE. In vivo imaging on male and female subjects was conducted using a 3.0T in modal and head register. 3D MRI data were included into segmentation to derive boundary conditions for finite-element models of vocal fold oscillation. Thereby, the segmented air volume of the larynx is transformed in splines at different positions in the anterior-posterior axis of the vocal folds.