Swallowing Evaluation by Estimating Bolus Velocity Changes due to Different Viscosities

To prevent aspiration, which may lead to aspiration pneumonia, a thickener is conventionally used to increase the viscosity of swallowed liquids. However, there is no quantitative index of the viscosity of the liquids corresponding to the swallowing ability. Therefore, we propose a method for estimating the bolus velocity, which can act as such an index, using an ultrasound video captured during swallowing. We divide the video into four regions and estimate the bolus velocity for each region. The results show that liquids with higher viscosity tend to result in a smaller temporal change in the bolus velocity.