Contrast-Enhanced ultrasound of the liver is a method used for a more detailed analysis of focal changes in the liver. Focal changes can be tumors, cysts, parts of uninfected tissue, and some other conditions. In some cases, it is not possible to accurately determine the nature of observed changes only on the basis of a classic ultrasound examination, so additional processing is recommended. It can include a check-up of computerized tomography (CT), magnetic resonance (MR) with or without contrast, and contrast ultrasound. Based on the appearance of focal changes after intravenous contrast application, it is usually possible to clarify the nature of such a change and to avoid biopsy which is the ultimate method of diagnosing. Contrast ultrasound has diagnostic reliability similar to CT or MR, with the benefit of patient not being exposed to radiation, and the contrast applied (sulfur hexafluoride) has no harmful effect on the kidneys or liver. Contrast-Enhanced ultrasound is is considered a very safe method in general, with exceptionally rare and mild side effects to the contrast substance. It is not allowed to use contrast in patients with with known right-to-left shunt, severe pulmonary hypertension (pulmonary artery pressure> 90 mmHg), uncontrolled high blood pressure, and patients with respiratory distress syndrome. Also, contrast administration is not recommended in patients with unstable cardiovascular disease, pregnant women and nursing mothers.