In the last decade, methods to noninvasively quantify liver fibrosis have been developed. The first available method was transient elastography (TE).It is a single-element ultrasound transducer operating at 5 MHz built on the axis of a piston like vibrator. By pushing a button, low-frequency (50 Hz) transient vibrations are transmitted, and the generated elastic shear waves propagate through underlying tissues. Pulse-echo ultrasound acquisitions are used to follow the propagation of the shear wave and to measure its velocity .