Ultrasound elastography

Ultrasound elastography, also called as sono-elastography, is a modern evolutionary method of sonographic imaging. Techniques include shear wave elastography (also known as transient elastography) and strain elastography (also known as static or compression elastography). These techniques utilize sound waves for assessing the mechanical properties of tissues such as stiffness and elasticity in response to mechanical pressure on tissue. They are used for detecting different pathologies in tissues by using the differences of their aforesaid mechanical properties.

Ultrasound elastography is increasingly used as a non-invasive method to assess the degree of liver fibrosis in chronic liver disease and grade it accordingly because of the prognostic value .

Physics

Tissue stiffness is calculated using a physical property of tissue called Young's modulus, or modulus of elasticity. Young's modulus is defined as stress (the force placed on a cross-sectional area) for a certain material, divided by strain (i.e. deformation; in this case, tissue deformation).

Applications

Sonographic elastography has multiple clinical applications and is used

• to assess the degree of hepatic fibrosis and characterization of liver lesions
• to assess diffuse renal parenchymal changes and characterization of renal lesions
• in breast mass diagnosis
• in prostate cancer detection 
• in thyroid lesion characterization 
• in tendon imaging