Principle or ARFI quantitative measurement.
a) Schematic of principles of ARFI imaging in virtual touch quantification mode – b) Example of a SWV measurement of the right liver. Transmission of a longitudinal acoustic pulse leads to tissue displacement, resulting in shear wave propagation away from the region of excitation. The shear wave velocity is measured within a defined region of interest (ROI) using ultrasound tracking beams laterally adjacent to the single push beam. The shear velocity is estimated in a graphically displayed ROI measuring 1 × 0.5 cm. The shear wave propagation velocity is proportional to the square root of tissue elasticity.