**3. Confounders: pathological changes influencing liver stiffness in HCV patients**

Several technical and biological factors affect the performance of elastographic techniques due to an increase in LS unrelated to fibrosis. The former includes shear wave frequencies, location and depth of measurements, and device dependencies. The latter include ingestion of food prior to the examination, inflammation, cholestasis, hepatic venous congestion, and amyloid deposits [16, 17]. Inflammation in acute hepatitis might increase LS up to mimicking cirrhosis, returning to normal

### *Noninvasive Assessment of HCV Patients Using Ultrasound Elastography DOI: http://dx.doi.org/10.5772/intechopen.102294*

simultaneously with the decrease of liver transaminases. A study of 112 CHC patients found a higher value for LS in the case of F3-F4 stages of fibrosis and necroinflammatory activity of at least A2 compared to A0-A1 (14.6 and 6.2 kPa, p = 0.04) [18]. Therefore, it is recommended to consider transaminases' value before interpreting LS in order to avoid overestimation [19]. If ALT levels are 3 times the normal value, there is a risk of overestimating the fibrosis stage and this should be mentioned with the results [20].

Concerning cholestasis and heart failure with hepatic congestion, LS decreases after proper treatment, hence the effect on shear wave propagation [21, 22]. Of note, a study suggests FibroScan as a potential tool to reveal heart decompensation [23]. In addition, waist circumference may lead to both technical failure and higher LS, but studies show various results and are mainly referring to body mass index (BMI). This is common because central obesity is associated with low-grade inflammation, insulin resistance, and liver steatosis, increasing LS. Furthermore, male gender, dyslipidemia and statins are debated in this regard, with different results (**Table 1**) [29].


#### **Table 1.**

*Advantages and disadvantages of noninvasive elastographic techniques.*
