A new tissue harmonic imaging scheme with better fundamental frequency cancellation and higher signal-to-noise ratio

Abstract

Tissue Harmonic Imaging (THI) is a new ultrasound imaging technique, which uses the harmonic components generated by nonlinear acoustic propagation through human tissues to form an image. Several factors affect THI image quality. First, strong suppression of the fundamental signals is necessary to allow the full dynamic range of the harmonic signals to be seen. This will allow the full benefits of harmonic imaging to be seen. Second, since the harmonic components are much weaker (15-20 dB lower) than the fundamental, they must be enhanced as much as possible relative to noise. This will allow the maximum possible image penetration. This paper will compare the phase inversion technique with another data acquisition and processing scheme from the literature in terms of suppression of fundamental frequencies, and signal-to-noise ratio (SNR) improvement. The comparison will be both theoretical, using a very simple model, and experimental, using data acquired in vitro. The phase inversion technique appears to be a better choice to realize THI in an ultrasound imaging system. This technique gives better cancellation of the fundamental frequencies while simultaneously improving SNR.