The role of CEUS in the characterization of hepatocellular nodules detected during the US surveillance program--current practices in Europe.

The basic pathological feature for the differential diagnosis between hepatocellular carcinoma (HCC) and non-malignant hepatocellular nodules in cirrhotic patients detected during ultrasound (US) is the vascular supply to the nodule. Computed tomography (CT) and magnetic resonance imaging (MRI) are considered reference imaging techniques for depicting hepatocellular nodule vascularity in the noninvasive diagnosis of HCC. Contrast-enhanced US (CEUS) improves the diagnostic performance of unenhanced US in the diagnosis of HCC, giving an overall diagnostic accuracy that is similar to that of CT, even for nodules smaller than 2 cm. An additional diagnostic feature of CEUS relative to CT is the possibility to visualize contrast wash-in to hepatic nodules during the arterial phase and contrast washout during the portal venous and late phases. Sensitivity for the diagnosis of HCC with combined assessment of CEUS and CT is higher than for separate assessments of CEUS and CT due to the reduction of false-negative findings. CEUS represents a competitive imaging method from an economic point of view, and is an effective imaging tool for assessing the therapeutic outcome after surgery, ablation therapy, and transarterial chemoembolization (TACE).