2019 Volume 58 Issue 2 Pages 79-85
Objectives: Video fluoroscopy （VF） is the most commonly used imaging method for evaluating swallowing motions. Other methods include video endoscopy （VE） and ultrasonography （US）. While VF provides clear images of the entire swallowing process, it involves exposure to X-rays and captures 3D movements on 2D images. VE is primarily used for imaging the pharyngeal phase of swallowing, and it is not suitable for evaluating the oral phase. On the other hand, US does not involve radiation exposure and can be used for both 3D and 4D imaging. Some studies have demonstrated that US systems can be used to evaluate swallowing functions in 3D and 4D, which is not possible with conventional VF. However, the image quality of US is affected by the image acquisition settings, the function and shape of the probe, and the texture of the food being swallowed during the examination. In the present study, we aimed to determine the efficacy of US for evaluating tongue movement. Specifically, we sought to determine the optimal image acquisition settings and types of food for evaluating tongue and bolus movements. We also examined the utility of novel software, which was specifically designed for analyzing tongue movement. Methods: The Voluson 730 US system （GE Healthcare Japan） and RABA4-8L 3D/4D convex US probe were used. One healthy volunteer was imaged using various image acquisition settings to assess image quality. In addition, the following types of food, which were considered safe and convenient for the purposes of swallowing examinations, were tested: liquids: tea or carbonated water; jelly: agar, agar＋baking soda, or agar＋soft drink; solids: a steamed bun, a pie, udon noodles, a cracker, or Mousse-UpⓇ＋soft drink）. The images were evaluated visually by an oral radiologist. Selected images that were of sufficient quality were saved in BMP format and analyzed using an analytical platform （Ratoc System Engineering Co., Ltd.）, comprised of an existing 4D fast image viewer and 3D image analysis software, and novel software （“Tongue Movement MOVIE software”）, which was specifically designed for delineating tongue and bolus movements. Results and Discussion: We demonstrated that use of the 3D/4D US system and novel analytical software designed for analyzing tongue movements was effective at delineating tongue movements and bolus movements at the back of the tongue. The images were of higher quality than the original images, and could be acquired in any direction. Although further evaluations are required to allow this method to be used in routine clinical practice, our findings suggest that it was useful for assessing tongue and bolus movements during the oral phase of swallowing. This study received a Grant-in-Aid for Scientific Research （25462931）.