Variability in Ultrasound Measurement of Hyoid Bone Displacement and Submental Muscle Size Using 2 Methods of Data Acquisition.

OBJECTIVE: This study compares variability in measures of hyoid bone displacement and submental muscle size using 2 methods of ultrasound transducer placement: fixed and hand-held. PATIENTS AND METHODS: Twenty-four healthy participants (11 males, 13 females) aged between 51 and 84 years were scanned using both methods. Repeated measures were collected within and across 3 sessions. RESULTS: A nonlinear mixed effects model was used to estimate the effects of the method, trial, and session. The fixed transducer produced greater within- and across-session variability on several measures compared to the hand-held method. Fixed-transducer measurements of hyoid bone displacement were 9.4% smaller compared to hand-held measurements (F[1, 24.34] = 3.58, p = 0.07). CONCLUSION: Results suggest that using a fixed transducer does not necessarily improve measurement accuracy of swallowing outcomes in a healthy system. The wide variability in individual measures indicates that further research is required before ultrasound is used for outcome measurement in rehabilitation.