Hepatocellular nodules in liver cirrhosis: contrast-enhanced ultrasound.

Contrast-enhanced ultrasound (CEUS) using microbubble contrast agents has expanded the role of US in the diagnosis of liver nodules in high risk patients for hepatocellular carcinoma (HCC). HCC is typically characterized by arterial hypervascularity and later washout (negative enhancement). Washout in the portal phase is often not obvious until late (>90 s). Benign nodules such as regenerative nodules or dysplastic nodules are usually isoechoic or slightly hypoechoic in the arterial and portal venous phases. However, there are occasional cases with overlap of imaging features between benign and malignant nodules, including hypovascular HCC and hypervascular HCC without washout. CEUS is helpful to characterize potential mimickers of HCC on imaging such as nontumorous arterioportal shunt or hemangioma. CEUS is also useful for a guidance of percutaneous local therapy of HCC and post-procedure monitoring of therapeutic response. CEUS can be effectively used in the diagnostic algorithm of small (1-2 cm) newly detected nodules during HCC surveillance.