Multi resolution transverse oscillations for motion estimation in ultrasound images

In recent work, motion estimation in ultrasound (US) image sequences has been conducted thanks to a phase based motion estimator working with the so-called transverse oscillations (TO) images obtained using specific beamforming in reception. In this paper, the nonlinear behavior of the medium is considered and the TO images are created at the fundamental but also at the second-harmonic frequency. With such images, a multi resolution transverse oscillations (MRTO) approach has been designed in order to measure the motion in US images sequences. A first estimation is conducted on the TO fundamental image, which is then improved by the TO second-harmonic one. The resulting motion estimation, quantitatively assessed both in simulations and experimentally, is strongly improved, in terms of mean motion value and standard deviation, compared to the motion estimated only using the fundamental TO image. The resulting error is reduced from 35% to 7% for high displacement values.