Assessing Soft Palate Movement at 15 Frames per Second Using Real-Time MRI

Introduction: Velopharyngeal insufficiency (VPI) is a condition in which the soft palate fails to block airflow into the nose in up to 28% of patients with cleft palate. Hypernasal speech is common in patients with VPI, where most consonant sounds are generated by inappropriate airflow through the nose. Current clinical measurements to assess speech are invasive, uncomfortable, or involve exposure to radiation. Advances in MRI technology and image reconstruction have led to fast image acquisition with high in-plane resolution. This emerging technology, so called real-time MRI, provides continuous imaging of moving structures, which allows functional, noninvasive assessment of internal organs. In this study, we developed a real-time MRI sequence to provide non-invasive, dynamic visualization of the soft palate in subjects while speaking.

Methods: All studies were conducted at a 3T MRI Philips scanner following IRB approval. Subjects were examined in a supine position. High-resolution MR-images were acquired using a head MRI coil to visualize and plan the MR images. Real-time MRI studies were acquired at 15 frames per second using highly under-sampled RF spoiled radial FLASH MRI sequence (TR=2.22ms, TE= 1.44ms, flip angle 5°, spokes 25, slice thickness 10 mm). Participants were asked to performed different speech assignments to assess the soft palate dynamic function. Image reconstruction by regularized nonlinear inversion was performed using algorithms written in MATLAB.

Results: We developed a real-time MRI sequence that provided high image quality at a scan rate of 15 frames/sec. Besides the clinical demonstration of the feasibility of real time MRI in evaluating speech, the primary result provided detailed information regarding the soft palate and the posterior pharyngeal wall in motion while speaking.

Conclusion: Real-time MRI provides non-invasive, dynamic visualization of palatal movement during speech that can assess the soft palate function in patients who underwent cleft palate repair.