A normalization method for axial-shear strain elastography

The axial-shear strain distribution of soft tissue under load contains information useful for differentiating benign and malignant tumors. This paper describes a novel axial-shear strain normalization method. The algorithm builds on an existing normalization procedure for axial strain to map the shear strain values to the range [ -π/2, π/2]. The normalized shear data do not change sign with the direction of axial probe motion, and therefore can be time averaged without loss of information. Experiments in simulation, in vitro, and in vivo confirm the advantages of normalization. The proposed method is well suited to freehand strain imaging and enables the visualization of subtle slip patterns around inclusions.