**2.2 Shear wave elastography for FLLs evaluation**

SWE assesses quantitative information regarding tissue stiffness by evaluating shear wave attenuation. These methods use dynamic ultrasound-induced force to generate shear waves by acoustic radiation force impulses [21]. Measuring the shear wave speed, we can obtain quantitative measurements of tissue elasticity. The stiffness value is provided by the shear wave velocity (SWV) in meters per second (m/sec) or by converting Young's modulus in kiloPascals (kPa) [21, 29]. The main three SWE techniques used in clinical practice are:


TE is validated for liver fibrosis assessment [30]. However, it is not feasible for FLL stiffness evaluation because this method is used without direct B-mode US image guidance and cannot accurately where the lesion is localized.
