Displacement and strain estimation based on numerical optimization method with powell algorithm and wavelet analysis in ultrasound elastography

Displacements estimated from two ultrasound echo signals acquired before and after applying quasi-static external forces can be utilized to generate strain images for ultrasound elastography. In this study, a displacement and strain estimation method based on numerical optimization method with Powell algorithm and wavelet analysis (NOMPA-WA) is proposed. Compared with the original numerical optimization method with Powell algorithm (NOMPA), the improvement of this method is that the setting of windows size is self-adaptive based on wavelet analysis of strains calculated from initial estimated displacements. Compared with original NOMPA, the proposed method produces fewer errors in the area with sharper transition by different tissues motion in the simulation experiment. Overall, it reduces strain estimation errors by 10.1% to 7.7% in this area.