Examination of Image Processing Method and Image Selection Method for Region of Interest Extraction in an Ultrasound Moving Image for Swallowing Evaluation

Abstract

Pneumonia is the main cause of death in Japan, with many deaths relate to aspiration pneumonia. However, there are no quantitative indicators for a noninvasive swallowing assessment. Typically, pharyngeal ultrasoundvideos (B-mode) are used as a noninvasive examination method. However, because determining an appropriate probe angle is difficult, the probe angle has typically been evaluated manually and empirically. In this study, a novel moving-image-processing method is evaluated for use in determining the probe angle. In each frame of both the moving and reference images, the similarity in discrete wavelet transform are calculated and discriminated. Results show that because the method analyzes similarity between the reference and original moving image, the Level 2 or 3 y-direction wavelet spaces are superior. As such, it is possible to determine an appropriate probe angle. Finally, to deal with individual differences, a matrix is created to determine the probe angle from the reference and moving images created from multiple subjects, and the reference images are selected.