Use of MRI in assessing structural and functional aspects of the velopharyngeal mechanism: evolution and current trends

The complex and dynamic nature of the velopharynx makes it a difficult area to assess, particularly during speech. The velopharynx, including the velum, lateral pharyngeal walls, and posterior pharyngeal walls are deep within the head and are surrounded by air spaces and tissues including muscle and bone .The primary muscle for velar elevation is the levator muscle. The location of the velopharyngeal mechanism, its underlying musculature like the levator muscle, and its surrounding tissue prove to be difficult in allowing certain types of scans and technology to obtain a clear image of the mechanism (Yamawaki et al., 1997). In previous years, nasoendoscopy and videofluoroscopy have both been used to study and view the velopharyngeal mechanism. Neither nasoendoscopy, videofluoroscopy, nor CT scans provide a visual of the underlying musculature of the velopharyngeal mechanism. MRI scans are the only form of technology that offers a view of the underlying musculature from multiple planes and enables in vivo visualization of the levator muscle without the use of ionizing radiation (Ettema et al., 2002). Varying subject populations, stimuli, and variables contribute to velopharyngeal mechanism data obtained through MRI scans. While MRI cannot replace certain aspects of nasoendoscopy and videofluoroscopy, it does provide a noninvasive, repeatable test that can be used as an alternative to the studies mentioned. The purpose of the paper is to analyze current trends and the evolution of the application of MRI in assessing the velopharyngeal mechanism