Ultrasound-based hepatic elastography: origins, limitations, and applications

A reliable, noninvasive marker to help clinicians evaluate hepatic fibrosis is urgently needed. The liver biopsy, an imperfect gold standard, has recognized limitations including sampling error and interobserver variability. Hepatic elastography (HE) is a novel sonographic method for assessing liver stiffness and has excellent accuracy in making the diagnosis of minimal fibrosis and cirrhosis. Several conditions intrinsic to the pathology of the liver compromise the positive predictive value of HE for fibrosis alone including acute hepatitis, obstructive cholestasis, and passive congestion. Technical considerations that hinder the performance of elastography include an advanced body mass index, the presence of ascites and narrow intercostal spaces. Despite these limitations, elastography has a role in staging fibrosis, prognosis of disease outcome, surveillance, and treatment decisions. HE is now being used in lieu of liver biopsy to investigate the natural history of chronic liver diseases. Additional studies are required to better define the appropriate role of HE in clinical practice.