Effects of Polyurethane Absorber for Improving the Contrast between Fascia and Muscle in Diagnostic Ultrasound Images

Abstract

In ultrasound diagnostics, acoustic absorbers block unwanted acoustic energy or prevent the reception of echo signals from structures outside the target area. Non-metallic absorbers provide a low-echoic signal that is suitable for observing the anatomy of the area to which the absorber is attached. In this study, we aimed to evaluate the effect of a polyurethane film absorber (PU) on ultrasound diagnostic imaging and investigate its effectiveness in improving the image contrast between the fascia and muscle structures. Twenty-six healthy men in their twenties participated in this study. The experiment was performed with the participant in the supine position and with an ultrasound transducer probe placed at the center of the measurement area on the abdomen. Images of the rectus abdominis (RA; muscle) and rectus sheath, e.g., fascia including superficial fascia (SF) and deep fascia (DF), obtained after attaching a PU, were compared with those obtained without the absorber (No_PU). The thickness was measured using brightness mode ultrasound imaging. To analyze the quantitative differences in the fascia and muscle images depending on the presence of the absorber, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were derived from the signal intensities measured in the target areas. The thickness of the fascia and muscle was similar in all regions of interest, regardless of the absorber; therefore, the existing diagnostic value was maintained. Overall, the signal intensity decreased; however, the SNRs of the RA, SF, and DF differed significantly. The SNR of the RA decreased in the PU but increased for the SF and DF. The CNRs for SF-RA and DF-RA significantly increased with the PU. In this study, we demonstrated that the PU behaved similarly to previously used metallic absorbers, reducing the signal from the attachment site while accurately indicating the attachment site in the ultrasound images. Furthermore, the results showed that the PU efficiently distinguished fascia from surrounding tissues, which could support studies requiring increased signal contrast between fascia and muscle tissue and aid the clinical diagnosis of fascial diseases.