A four-dimensional motion field atlas of the tongue from tagged and cine magnetic resonance imaging

Abstract

Representation of human tongue motion using three-dimensional vector fields over time can be used to better understand tongue function during speech, swallowing, and other lingual behaviors. To characterize the inter-subject variability of the tongue’s shape and motion of a population carrying out one of these functions it is desirable to build a statistical model of the four-dimensional (4D) tongue. In this paper, we propose a method to construct a spatio-temporal atlas of tongue motion using magnetic resonance (MR) images acquired from fourteen healthy human subjects. First, cine MR images revealing the anatomical features of the tongue are used to construct a 4D intensity image atlas. Second, tagged MR images acquired to capture internal motion are used to compute a dense motion field at each time frame using a phase-based motion tracking method. Third, motion fields from each subject are pulled back to the cine atlas space using the deformation fields computed during the cine atlas construction. Finally, a spatio-temporal motion field atlas is created to show a sequence of mean motion fields and their inter-subject variation. The quality of the atlas was evaluated by deforming cine images in the atlas space. Comparison between deformed and original cine images showed high correspondence. The proposed method provides a quantitative representation to observe the commonality and variability of the tongue motion field for the first time, and shows potential in evaluation of common properties such as strains and other tensors based on motion fields.

Speech Map: a statistical multimodal atlas of 4D tongue motion during speech from tagged and cine MR images

“…Another strategy is to use similar processes applied to an Eulerian configuration rooted in the spatial coordinates, such as reported in [12]. Such a “moving atlas” allows for visualization of the moving tongue anatomy parallel to the cine-MRI in the form of changing motion fields during speech.…”

“…Several approaches have been proposed to construct such 4D atlases. Xing et al [12] proposed a 4D multimodal atlas of the tongue during speech within an Eulerian framework. In the present work, we also used both cine- and tagged-MRI, but adopted a Lagrangian framework, where the reference anatomic configuration remains fixed, while motion fields change in the course of speech.…”

“…This approach allows us to quantitatively assess differences in speech movements across speakers and speech-impaired populations. In contrast to the previous methods of tongue imaging in spatial coordinates [10, 12], our approach provides movies of the tongue in material coordinates. In addition, each subject’s tongue motion is transformed to the common anatomical configuration, thereby allowing us to objectively compare patients to the atlas and to each other.…”

Group characterization of impact-induced,in vivohuman brain kinematics

“…We constructed the average displacement field Ufalse¯false(X¯false) by calculating the mean displacement at each node. This is similar to statistical treatment of cardiac and speech data [39,40], but unlike these previous works we used an inertially weighted mean of the transformed nodal values, i.e.Ufalse¯false(X¯false)=1N∑i=1N⁡WiRiUi(Xfalse¯) ,where Ri and Wi were extracted using the description above. The measure of inter-participant variability (or spread) in the displacements is the standard deviation of the displacement δUfalse(X¯false), which was computed using Welford's algorithm to reduce memory usage due to the large number of mesh elements [41].…”

Strain map of the tongue in normal and ALS speech patterns from tagged and diffusion MRI

“…Since atlases of the tongue have been a useful tool in analyzing motion in subject-specific spaces [16] , they can be applied in various scenarios to provide missing information in a statistical way. In this work, although ALS patient-specific motion quantities are difficult to measure, we use a motion atlas to approximate their motion and strain during speech, while we use DTI to focus on revealing these patients’ structural change in their internal muscle fibers.…”