Acoustic Radiation Force Impulse Imaging (ARFI) : a New Technique to Assess Liver Elasticity

Overview

Liver stiffness measurement (LSM) by non invasive methods is increasingly used to estimate liver fibrosis in patients with chronic liver diseases. However, there is growing evidence that fibrosis is not the only determinant of liver stiffness. Indeed inflammation, cholestasis, congestion could also interfere with stiffness measurements. Acoustic radiation force impulse imaging (ARFI) is a new technology to perform real time LSM. Using a standard ultrasonographic probe, it offers elastography with a flexible metering box at variable depth, allowing the examination of specific area.

There are many causes of chronic liver diseases such as hepatitis C infection, hepatitis B infection, alcohol, NAFLD (non-alcoholic fatty liver disease), drugs and auto-immune liver disease. Although the causes differ the pathological response to injury tends to be similar leading to fibrosis and cirrhosis. Liver biopsy is the current gold standard for the assessment of liver fibrosis but is poorly suited for active monitoring because of its expense and morbidity. Thus, development of alternatives that are safe, inexpensive, and reliable is a priority. Liver stiffness measurement (LSM) by non invasive method is increasingly used to estimate liver fibrosis in patient with chronic liver disease. Acoustic radiation force impulse imaging (ARFI) is a new technology to perform real time LSM. Using a standard ultrasonographic probe, it offers elastography with a flexible metering box at variable depth, allowing the examination of specific area. The purpose of this work was to evaluate by ARFI, the efficiency of this new technique, the reproducibility inter and intra observer, and the liver elasticity obtained by this method in different patient groups. The primary endpoint of this work is to evaluate by ARFI, the efficiency of the technique, the reproducibility inter and intra observer, and the elasticity of liver in 6 different patient groups and healthy volunteers. The different population groups are: * healthy volunteers Group A * patients with supposed disease free liver (normal hepatic and pancreatic biochemistry). Group B * patients with non cirrhotic hepatopathy. Group C * patients with cirrhosis. Group D * patients with liver tumour and surgery indication. Group E * patients with reversible liver diseases: * patients with acute left cardiac insufficiency. Group F * patients with biliary cholestasis. Group G ARFI measurements will be performed in a single liver ultrasound exam visit except for patients with reversible liver diseases who will have a second visit with ARFI measurement after clinical healing. The ARFI values are expressed as a speed in m/s.