Contrast-enhanced ultrasound approach to the diagnosis of focal liver lesions: the importance of washout Hyun Kyung Yang1, Peter N. Burns2, Hyun-Jung Jang1, Yuko Kono3, Korosh Khalili1, Stephanie R. Wilson4, Tae Kyoung Kim1 REVIEW ARTICLE 1Joint Department of Medical Imaging, University of Toronto, Toronto; 2Department of https://doi.org/10.14366/usg.19006 pISSN: 2288-5919 • eISSN: 2288-5943 Medical Biophysics, Sunnybrook Research Institute, University of Toronto, Toronto, Canada; Ultrasonography 2019;38:289-301 3Departments of Medicine and Radiology, University of California, San Diego, CA, USA; 4Diagnostic Imaging, Department of Radiology, University of Calgary, Calgary, Canada Received: January 15, 2019 Contrast-enhanced ultrasound (CEUS) is a powerful technique for differentiating focal liver Revised: March 13, 2019 lesions (FLLs) without the risks of potential nephrotoxicity or ionizing radiation. In the diagnostic Accepted: March 17, 2019 algorithm for FLLs on CEUS, washout is an important feature, as its presence is highly suggestive Correspondence to: Tae Kyoung Kim, MD, PhD, FRCPC, of malignancy and its characteristics are useful in distinguishing hepatocellular from non- Department of Medical Imaging, hepatocellular malignancies. Interpreting washout on CEUS requires an understanding that Toronto General Hospital, 585 University Avenue, Toronto, ON M5G microbubble contrast agents are strictly intravascular, unlike computed tomography or magnetic 2N2, Canada resonance imaging contrast agents. This review explains the definition and types of washout on Tel. +1-416-340-3372 CEUS in accordance with the 2017 version of the CEUS Liver Imaging Reporting and Data System Fax. +1-416-593-0502 E-mail:
[email protected] and presents their applications to differential diagnosis with illustrative examples.