**2. Fibrosis assessment in HCV patients using noninvasive elastographic methods: a classification**

Elastography-based imaging techniques quantify tissue stiffness, defined as the resistance of a material in response to an applied mechanical force [12]. Fibrosis modifies the elastic properties of liver tissue so that new techniques have been developed in the past two decades to grade liver fibrosis according to tissue stiffness.

Ultrasonographic (US) and magnetic resonance-based elastographic techniques are available, of which we will focus on US methods. Several guidelines classify elastographic techniques in two main categories: quantitative ("Shear Wave Elastography", SWE) and qualitative ("Strain Elastography) [13–15]. Regarding CHC, quantitative methods are most frequently used to evaluate liver stiffness (LS). Currently, three main quantitative techniques showed promising results in this pathology: Vibration Controlled Transient Elastography (VCTE; FibroScan®, Echosens, Paris, France) point-shear wave elastography (pSWE), and 2D- shear wave elastography (2DSWE). For integrative purposes, we decided to summarize the specific advantages and limitations of each technique in HCV patients.
