1From the Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Tex (D.T.F.); Departments of Medical Physics (I.M.R.M., T.J.H.) and Radiology (I.M.R.M.), University of Wisconsin, Institutes for Medical Research, 1111 Highland Ave, Room 1005, Madison, WI 53705; General Electric Healthcare, Milwaukee, Wis (M.W.); Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala (M.L.R.); Department of Radiology, Massachusetts General Hospital, Boston, Mass (A.O.); U.S. Food and Drug Administration, Silver Spring, Md (K.A.W.); Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY (J.O.); Department of Natural Sciences, Kettering University, Flint, Mich (T.A.S.); Departments of Biomedical Engineering and Radiology, University of Michigan, Ann Arbor, Mich (J.B.F.); RSNA Quantitative Imaging Biomarkers Alliance (T.J.H.); and Center for Ultrasound Research & Translation, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Mass (A.E.S.).
Excessive liver fat (steatosis) is now the most common cause of chronic liver disease worldwide and is an independent risk factor for cirrhosis and associated complications. Accurate and clinically useful diagnosis, risk stratification, prognostication, and therapy monitoring require accurate and reliable biomarker measurement at acceptable cost. This article describes a joint effort by the American Institute of Ultrasound in Medicine (AIUM) and the RSNA Quantitative Imaging Biomarkers Alliance (QIBA) to develop standards for clinical and technical validation of quantitative biomarkers for liver steatosis. The AIUM Liver Fat Quantification Task Force provides clinical guidance, while the RSNA QIBA Pulse-Echo Quantitative Ultrasound Biomarker Committee develops methods to measure biomarkers and reduce biomarker variability. In this article, the authors present the clinical need for quantitative imaging biomarkers of liver steatosis, review the current state of various imaging modalities, and describe the technical state of the art for three key liver steatosis pulse-echo quantitative US biomarkers: attenuation coefficient, backscatter coefficient, and speed of sound. Lastly, a perspective on current challenges and recommendations for clinical translation for each biomarker is offered.