The introduction of microbubble contrast agents and the development of contrast-specific scanning techniques have opened new prospects in ultrasound. The advent of second-generation agents that enable real-time contrast-enhanced imaging has been instrumental in improving the acceptance and the reproducibility of examinations. Contrast ultrasound substantially improves detection and characterization of focal liver lesions with respect to baseline studies, and has already been introduced in international guidelines for the diagnosis of liver tumors. The role of contrast agents in vascular ultrasound is also established, and several new clinical applications are emerging. This book, written by the leading experts in the field, provides an up-to-date overview on the clinical value of contrast agents in ultrasound. The volume moves from a background section on technique and methodology to the main sections on the clinical application of contrast ultrasound in the liver and in vascular diseases. A final section discusses results and prospects of contrast ultrasound modality in the other fields.