Improved Depiction of Tissue Boundaries in Vocal Tract Real-Time MRI Using Automatic Off-Resonance Correction

Real-time magnetic resonance imaging (RT-MRI) is a powerful tool to study the dynamics of vocal tract shaping during speech production. The dynamic articulators of interest include the surfaces of the lips, tongue, hard palate, soft palate, and pharyngeal airway. All of these are located at air-tissue interfaces and are vulnerable to MRI off-resonance effect due to magnetic susceptibility. In RT-MRI using spiral or radial scanning, this appears as a signal loss or blurring in images and may impair the analysis of dynamic speech data. We apply an automatic off-resonance artifact correction method to speech RT-MRI data in order to enhance the sharpness of air-tissue boundaries. We demonstrate the improvement qualitatively and using an image sharpness metric offering an improved tool for speech science research.