Comparison of Tongue Hardness at Rest and When Holding Water in the Mouth Using Ultrasound Real-time Tissue Elastography

Abstract

　Sarcopenia, which is defined as loss of muscular mass, strength, and quality associated with aging, may also occur in the oral region of elderly people. In this study, ultrasound real-time tissue elastography（Noblus, Hitachi, Tokyo）was used to determine tongue hardness. However, to the best of our knowledge, there are no previous studies applying this method to the tongue. We applied the method to 10 healthy volunteers（5 men and 5 women）with a mean age of 26.1±1.1 years. We measured the hardness and thickness of the tongue with the subjects in a seated position at rest, and while holding 3 mL of water and thickened water in the mouth. The strain ratio（SR）from real-time tissue elastography was used to measure tongue hardness. Seven images were recorded for each subject under each test condition. The tongue thickness and hardness were measured, and the mean value was set as the representative value. Repeated measure one-way ANOVA and Spearmanʼs correlation were used for statistical analysis. The median SR values for the 10 subjects were 0.69 at rest, 0.48 when holding water, and 0.44 when holding thickened water. A significant difference was seen in tongue hardness at rest and that when holding water. The concavity of the tongue when holding water had a negative significant correlation with tongue hardness at rest and that when holding water. This suggests that strain elastography can be applied to external measurement of tongue hardness under certain conditions. Further research is needed on measurements of the tongue in elderly individuals using ultrasound elastography to investigate age-related changes, including conducting the test under other conditions.