Title: Review of ultrasound elastography techniques in the liver

Abstract

Liver fibrosis is a multifactorial chronic parenchymal disorder that can lead to cirrhosis with detrimental complications like portal hypertension and development of hepatocellular carcinoma. Until recently the gold standard for diagnosing liver cirrhosis and fibrosis has been liver biopsy. However associated complications are pain, bleeding, infection, and puncture of other organs. Another limitation is sampling error, that can lead to false negative results, and the potential need for sedative measures. Thus noninvasive imaging modalities have been investigated with the goal to replace invasive biopsy. Since hepatic fibrosis is associated with loss of elasticity (i.e. increased stiffness) of hepatic parenchyma, imaging and quantification methods for stiffness including magnetic resonance imaging elastography (FMRE) and ultrasound elastography (UE) have been developed, with the concept of measuring the degree of tissue stiffness as a surrogate marker for the stage of fibrosis. In this article we give an introduction to the various sonographic principles of ultrasound elastography, describe the advantages and limitations of the different techniques. We discuss how to set up and perform liver elastography in daily practice and how to apply the guidelines setup by various societies along with measures for quality assurance including training of sonographers and appropriate interpretation of images. Finally, the potential pitfalls and artifacts seen in liver UE are discussed as well.

Keywords

Liver fibrosis, chronic parenchymal disorder, cirrhosis, hepatocellular carcinoma, hepatic fibrosis, hepatic parenchyma