In vitro evaluation of the ringdown artifact with findings consistent with linear superposition of narrowband waves

In B-mode medical ultrasound, a ringdown artifact is a vertical, linear artifact composed of horizontal bands. In this study, in vitro ringdown artifact models are investigated. Frequency domain spectral analysis of the ringdown artifact shows narrowband peaks, with a difference frequency that matches the spacing of bands in the ringdown artifact. These data are consistent with linear superposition of narrowband waves. Reconstruction of individual focused pulse acquisitions visualizes a triangular ringdown artifact, indicating that the linear shape of the ringdown artifact may itself be an artifact of composite imaging.