Fig. 1

Basic physical principle of compression elastography (CE). The operator exerts compression on the tissue, generating a displacement (δ) that can be estimated by comparing the structure at rest and under compression. The strain (ε) is the ratio difference in displacement between two points to their distance pre-compression (L). The strain measurements are displayed as a colour map, called an elastogram, which is overlaid on the B-mode image. Typically, low strain (stiff tissue) is displayed in blue and high strain (soft tissue) is displayed in red