Understanding the underlying neural pathways that govern the highly complex neuromuscular action of swallowing is considered crucial in the process of correctly identifying and treating swallowing disorders. The aim of the present investigation was to identify the neural activations of the different components of deglutition in healthy young adults using functional magnetic resonance imaging (fMRI). Ten right-handed young healthy individuals were scanned in a 3-Tesla Siemens Allegra MRI scanner. Participants were visually cued for both a "Swallow" task and for component/control tasks ("Prepare to swallow", "Tap your tongue", and "Clear your throat") in a randomized order (event-related design). Behavioral interleaved gradient (BIG) methodology was used to address movement-related artifacts. Areas activated during each of the three component tasks enabled a partial differentiation of the neural localization for various components of the swallow. Areas that were more activated during throat clearing than other components included the posterior insula and small portions of the post- and pre-central gyri bilaterally. Tongue tapping showed higher activation in portions of the primary sensorimotor and premotor cortices and the parietal lobules. Planning did not show any areas that were more activated than in the other component tasks. When swallowing was compared with all other tasks, there was significantly more activation in the cerebellum, thalamus, cingulate gyrus, and all areas of the primary sensorimotor cortex bilaterally.

Purpose: To evaluate the impact of magnetic field inhomogeneity correction on achievable imaging speeds for magnetic resonance imaging (MRI) of articulating oropharyngeal structures during speech and to determine if sufficient acquisition speed is available for visualizing speech structures with real-time MRI. Materials and Methods:We designed a spiral fast low angle shot (FLASH) sequence that combines several acquisition techniques with an advanced image reconstruction approach that includes magnetic field inhomogeneity correction. A simulation study was performed to examine the interaction between imaging speed, image quality, number of spiral shots, and field inhomogeneity correction. Six volunteer subjects were scanned to demonstrate adequate visualization of articulating structures during simple speech samples. Results:The simulation study confirmed that magnetic field inhomogeneity correction improves the available tradeoff between image quality and speed. Our optimized sequence co-acquires magnetic field maps for image correction and achieves a dynamic imaging rate of 21.4 frames per second, significantly faster than previous studies. Improved visualization of anatomical structures, such as the soft palate, was also seen from the field-corrected reconstructions in data acquired on volunteer subjects producing simple speech samples.Conclusion: Adequate temporal resolution of articulating oropharyngeal structures during speech can be obtained by combining outer volume suppression, multishot spiral imaging, and magnetic field corrected image reconstruction. Correcting for the large, dynamic magnetic field variation in the oropharyngeal cavity improves image quality and allows for higher temporal resolution. MAGNETIC RESONANCE IMAGING (MRI) has long been considered as a tool with great potential for examining soft tissue movements associated with speech. Neither x-ray video fluoroscopy nor nasoendoscopy are able to provide unobstructed visualization of the moving soft tissues, including underlying musculature, whereas MRI can provide dynamic images of soft tissues and underlying musculature in any arbitrary plane. The early applications of MRI to speech research were restricted by long image acquisitions that were not fast enough to capture the natural movements of vocal tract articulators (1-4). As a result, many researchers focused on sustained vowels and fricatives that keep the vocal tract still for up to several seconds to compensate for the low temporal resolution. Examples of early research include extraction of vocal tract transfer functions (5) and evaluation of velopharyngeal insufficiencies in patients with motor dysfunctions (3) or in patients who had surgery to repair cleft palate (6).In order to resolve faster articulatory movements during speech, later studies took advantage of MRI techniques that divide an image acquisition over as many as 128 repetitions of the motion of interest (7). These gated acquisitions acquire only part of k-space data for an image during a single repetition of a speec...

The present study successfully demonstrated the use of 3D MRI in quantifying major velopharyngeal structures and provided additional data on the anatomic variations that exist in healthy adult individuals.

Fast MRI combined with acoustic analysis was successfully applied to the investigation of acoustic-physiologic relationships of the velopharyngeal mechanism with the type of speech samples employed in the present study. Future applications are feasible to examine how anatomic and physiologic deviations of the velopharyngeal mechanism would be acoustically manifested in individuals with velopharyngeal incompetence.

Dynamic imaging with MRI holds great promise for visualizing soft tissue structures in the oropharyngeal region during speech and swallowing studies. However, MRI suffers from historically slow acquisition speed and sensitivity to significant magnetic susceptibility differences in this region. In this work, we describe our efforts in creating high temporal resolution, serial acquisitions of the muscles of the oropharyngeal region. We describe our imaging approach that leads to acquisition rates of up to 21 frames per second. Additionally, we compare the serial acquisition scheme to gated acquisitions that suffer from temporal blur due to limited repeatability of the dynamic action.