State of the Art: LI-RADS for Contrast-enhanced US

Abstract

Contrast material-enhanced (CE) US is a recognized imaging tool in the characterization of focal liver lesions and uses microbubble contrast agents to increase signal backscattering from the blood. The European Federation of Societies for Ultrasound in Medicine and Biology and the World Federation for Ultrasound in Medicine and Biology strongly recommend the use of CE US in the characterization of hepatocellular nodules in individuals with liver cirrhosis. CE US was recently approved by the Food and Drug Administration for liver indications in adult and pediatric patients. CE US Liver Imaging Reporting and Data System (LI-RADS) criteria were recently proposed by the American College of Radiology and include eight distinct diagnostic categories: LR-1 (definitely benign), LR-2 (probably benign), LR-3 (intermediate malignancy probability), LR-4 (probably hepatocellular carcinoma [HCC]), LR-5 (definitely HCC), LR-NC (cannot be categorized due to image degradation), LR-TIV (tumor in vein), and LR-M (probably or definitely malignant but not HCC specific). CE US LI-RADS criteria can be used to produce a structured report for HCC diagnosis. However, the variability of US equipment in terms of sensitivity to microbubble signal, interreader variability, large number of HCC nodules classified as LR-3, and wide washout temporal range for LR-M observations are limitations.