Research progress in evaluating velopharyngeal structures and functions by magnetic resonance imaging

Normal development of the velopharyngeal structures is key to obtaining good velopharyngeal closure. In the assessment of velopharyngeal closure and normal pronunciation, a variety of instruments can be used to detect and assist in the diagnosis of velopharyngeal dysfunction. In the past, the assessment of velopharyngeal closure often used two⁃dimensional imaging or relied solely on the subjective assessment of the phonetician. With the development of sci⁃ ence and technology, magnetic resonance imaging (MRI) has become widely used in the evaluation of velopharyngeal structures and functions as an ideal examination method. This article reviews the current capabilities and limitations in evaluating velopharyngeal closure, as well as recent research on the structures and functions of the velopharyngeal using static MRI, dynamic MRI, three⁃dimensional MRI reconstructions and diffusion tensor imaging (DTI) techniques; in ad⁃ dition, this work explores the role and significance of MRI technology in evaluating the structures and functions of the velopharyngeal. A review of the literature shows that static MRI is simple in terms of the scanning mode, has easily ad⁃ justable parameters, and clearly shows the anatomical structures of palatopharyngeal in resting or transient vocal states. Dynamic MRI can capture the anatomical changes of the palatopharyngeal in a more complex pronunciation state and obtain accurate dynamic images of the velopharyngeal closure process for the study of speech pathology. Three⁃dimen⁃sional MRI reconstructions are usually used in fine scanning of the velopharyngeal structures in a resting state; although this method takes a long time, the images obtained are clear and reliable. This approach can be used for three⁃dimen⁃ sional reconstruction analysis and three⁃dimensional finite element analysis, and it can be used to help plan an opera⁃ tion and evaluate the effect of the surgery. DTI is a new method for observing the contractile function of muscles by ob⁃ serving the locus of water molecules in muscles. DTI can be used to analyze and study many muscles involved in velo⁃ pharyngeal closure