Purpose To enable a more comprehensive view of articulations during speech through near‐isotropic 3D dynamic MRI with high spatiotemporal resolution and large vocal‐tract coverage. Methods Using partial separability model‐based low‐rank reconstruction coupled with a sparse acquisition of both spatial and temporal models, we are able to achieve near‐isotropic resolution 3D imaging with a high frame rate. The total acquisition time of the speech acquisition is shortened by introducing a sparse temporal sampling that interleaves one temporal navigator with four randomized phase and slice‐encoded imaging samples. Memory and computation time are improved through compressing coils based on the region of interest for low‐rank constrained reconstruction with an edge‐preserving spatial penalty. Results The proposed method has been evaluated through experiments on several speech samples, including a standard reading passage. A near‐isotropic 1.875 × 1.875 × 2 mm3 spatial resolution, 64‐mm through‐plane coverage, and a 35.6‐fps temporal resolution are achieved. Investigations and analysis on specific speech samples support novel insights into nonsymmetric tongue movement, velum raising, and coarticulation events with adequate visualization of rapid articulatory movements. Conclusion Three‐dimensional dynamic images of the vocal tract structures during speech with high spatiotemporal resolution and axial coverage is capable of enhancing linguistic research, enabling visualization of soft tissue motions that are not possible with other modalities.

Magnetic resonance (MR) imaging is becoming an established tool in capturing articulatory and physiological motion of the structures and muscles throughout the vocal tract and enabling visual and quantitative assessment of real-time speech activities. Although motion capture speed has been regularly improved by the continual developments in high-speed MR technology, quantitative analysis of multi-subject group data remains challenging due to variations in speaking rate and imaging time among different subjects. In this paper, a workflow of post-processing methods that matches different MR image datasets within a study group is proposed. Each subject's recorded audio waveform during speech is used to extract temporal domain information and generate temporal alignment mappings from their matching pattern. The corresponding image data are resampled by deformable registration and interpolation of the deformation fields, achieving inter-subject temporal alignment between image sequences. A four-dimensional dynamic MR speech atlas is constructed using aligned volumes from four human subjects. Similarity tests between subject and target domains using the squared error, cross correlation, and mutual information measures all show an overall score increase after spatiotemporal alignment. The amount of image variability in atlas construction is reduced, indicating a quality increase in the multi-subject data for groupwise quantitative analysis.

Traditional imaging modalities used to assess velopharyngeal insufficiency (VPI) do not allow for direct visualization of underlying velopharyngeal (VP) structures and musculature which could impact surgical planning. This limitation can be overcome via structural magnetic resonance imaging (MRI), the only current imaging tool that provides direct visualization of salient VP structures. MRI has been used extensively in research; however, it has had limited clinical use. Factors that restrict clinical use of VP MRI include limited access to optimized VP MRI protocols and uncertainty regarding how to interpret VP MRI findings. The purpose of this paper is to outline a framework for establishing a novel VP MRI scan protocol and to detail the process of interpreting scans of the velopharynx at rest and during speech tasks. Additionally, this paper includes common scan parameters needed to allow for visualization of velopharynx and techniques for the elicitation of speech during scans.

We are able to push the spatial resolution of dynamic speech magnetic resonance imaging to 2-mm near-isotropic level with 64 mm coverage of 32 3D slice locations that are spaced 2-mm apart with 35 fps. We choose to analyze lingual differences of American English voiced lateral [l] and (central) [t]. Several analysing methods are utilized such as magnitude comparison, t-test and deformation map comparison. The results give us detailed observations of lingual articulatory differences such as tongue grooving, twisting and coarticulation. Through this high spatial and temporal resolution, we demonstrate that this method will show great potentials on linguistic research.

Objective To introduce a highly innovative imaging method to study the complex velopharyngeal (VP) system and introduce the potential future clinical applications of a VP atlas in cleft care. Design Four healthy adults participated in a 20-min dynamic magnetic resonance imaging scan that included a high-resolution T2-weighted turbo-spin-echo 3D structural scan and five custom dynamic speech imaging scans. Subjects repeated a variety of phrases when in the scanner as real-time audio was captured. Setting Multisite institution and clinical setting Participants Four adult subjects with normal anatomy were recruited for this study. Main Outcome Establishment of 4-D atlas constructed from dynamic VP MRI data. Results Three-dimensional dynamic magnetic resonance imaging was successfully used to obtain high quality dynamic speech scans in an adult population. Scans were able to be re-sliced in various imaging planes. Subject-specific MR data were then reconstructed and time-aligned to create a velopharyngeal atlas representing the averaged physiological movements across the four subjects. Conclusions The current preliminary study examined the feasibility of developing a VP atlas for potential clinical applications in cleft care. Our results indicate excellent potential for the development and use of a VP atlas for assessing VP physiology during speech.