Imaging of focal liver lesions.

With a popular use of cross-sectional imaging, liver masses are often detected incidentally or seen on surveillance scans in high-risk or symptomatic patients. Noninvasive characterization of focal liver lesions is largely based on their enhancement patterns on contrast-enhanced imaging. Contrast-enhanced computed tomography (CT) or magnetic resonance (MR) imaging is most commonly used for the characterization of focal hepatic lesions. The recent use of microbubble contrast agents has significantly expanded the role of sonography in the diagnosis of focal liver lesions on the basis of their vascularity and specific enhancement features, with an advantage of a real-time imaging and strictly intravascular contrast agent. This article describes the features of commonly encountered benign and malignant liver lesions on sonography and contrast-enhanced dynamic imaging, including contrast-enhanced ultrasound (CEUS), CT, and MR imaging.