Using three-dimensional magnetic resonance imaging for assessing velopharyngeal structures in adults with repaired cleft palate

Objective Using three dimensional magnetic resonance imaging to investigate the differences in velopharyngeal structures and motion between normal resonance adults with repaired cleft palate and without cleft palate, to guide the surgical method of cleft palate repair surgery. Methods Twelve male adults, including 6 adults with repaired cleft palate (cleft group: age 18-26 years old, average 21.8 years old) and 6 adults without cleft palate (noncleft group: age 19-28 years old, average 23.3 years old) were examined with dynamic and static 3D MRI in midsagittal. 32 velopharyngeal measures including soft palate length, effective soft palate length, pharynx ratio, palate height, levator veli palatini muscle length and thickness were obtained on midsagittal, coronal, and levator veli palatine image plane(oblique coronal image plane)and compared between groups. The correlation test of two times data were carried out by Pearson product-moment correlation coefficient to determine the error size of the measurement result. Two separate sample t-tests was used to compare the two sets of data. Results All the subjects had no speech abnormalities, and velopharyngeal competence. Two measurements of the r value is 0.789 to 0.925 (P<0.05), which is twice the measurement error is within the acceptable range. The noncleft group of levator veli palatini muscle form is more fluid, while the cleft group is irregular, the middle line can be observed discontinuous phenomenon, and the levator veli palatini muscle insertion soft palate angle is obviously different. Compared to those without cleft palate, participants with repaired cleft palate had a significantly bigger pharynx wide(23.83±3.48) mm, pharynx deep(29.94±3.52) mm, bone pharynx deep(39.68±3.63) mm, palate length ratio(1.18±0.16), pharynx ratio(0.87±0.91), PVU angle (movement)(105.68±20.54)°, the intravelar segment of the levator veli palatini muscle(13.13±1.00) mm, insertion spacing(13.13±1.00) mm. and the starting angle of the levator muscle(58.0±3.3)°. In contrast, the width of the hard palate(37.5±1.43) mm, soft thicknes(9.48±1.03) mm, soft palate relative extension length (/ts/)(1.09±0.05) mm, the thickness of the levator veli palatini muscle(4.07±0.25) mm, APV angle (movement)(180.51±8.55)° and the starting distance of the levator muscle(52.27±7.08) mm are larger in the normal group, The differences are statistically significant(P<0.05). Conclusions Measuring the pharyngeal structure with three-dimensional magnetic resonance is feasible, and there are significant differences in the pharynx structure, soft palate and levator veli palatini muscle morphological structure of the adults with repaired cleft palate and without cleft palate. Attention to the anatomical reset of the levator muscle, especially the protection and extension of the the extravelar segment of the levator veli palatini muscle, and the extension of the effective soft palate when the soft flap is separated, should be noted in the early repair of the cleft palate. Key words: Magnetic resonance imaging; Cleft palate; Velopharyngeal; Levator veli palatini muscle