Shear wave elastography based on noise correlation and time reversal: From 1d to 3d shear elasticity imaging

Shear wave elastography (SWE) relies on the generation and tracking of coherent shear waves to image soft tissue’s shear elasticity. However, coherent shear wave tracking is not always possible due to scattered or interfering waves that arise from inhomogeneities, muscular activity, heart beating, or external sources. To overcome this limitation, we developed an alternative approach using a complex elastic wave-field. Based on the analogy between time reversal and seismic noise correlation, this complex field is “transformed” into a coherent converging-diverging time-reversal field using spatial-temporal cross-correlations [1]. Using the computed time reversal field, there are different ways to image the shear elasticity: tracking the coherent shear wave as it focuses, measuring the focus size (Rayleigh criteria) or evaluating the vibration amplitude at the focus [2]. One advantage of this approach is its compatibility with low imaging rates, which led to innovative applications in SWE. Thus, the goal of this talk is to review the major developments in wave-physics for 1D and 2D elasticity imaging using noise correlation of shear waves and to present its latest applications involving passive elastography and 3D elasticity imaging using row-column arrays. [1] Catheline, Phys. Rev. Lett. (2008); Brum, JASA (2008); Benech, IEEE-TUFFC (2009). [2] Brum, Front. Phys. (2021).