This lecture will cover the basics of contrast enhanced ultrasound (CEUS), which is primarily used in assessing organ vascularity/perfusion after the IV administration of an ultrasound specific contrast medium (gas-filled microbubbles). The lecture will discuss how CEUS can be used in imaging liver nodules and masses in small animal patients. This will be a case-based presentation that will show examples of benign and malignant liver lesions and how CEUS may be used to distinguish between them via the different patterns of blood flow in benignancy vs. malignancy. It will discuss how CEUS may be incorporated into the work-up of patients with liver nodules/masses, including the most appropriate times to utilize CEUS in these cases.