Elastography is a special ultrasound method in which stiffness or strain image of soft tissue are used to detect or classify tumors. Malignant tumors can be 5-28 times stiffer than the background of normal soft tissue. When a mechanical compression or vibration is applied, the tumor deforms less than the surrounding tissue. i.e. the strain in the tumor is less than the surrounding tissue.

This information can be use to produce a strain image for differentiation of lesions.