Elastografia epatica: metodiche a confronto

Background: The cirrhotic process of liver injury is the end-stage of hepatic fibrosis, which results from progressive accumulation of extracellular matrix during the wound-healing response of the liver to repeated injury.Mortality and morbidity rates increase exponentially once cirrhosis develops. Therefore, a prompt assessment of the degree of severity of fibrosis, an accurate and timely diagnosis of liver cirrhosis and management of complications are important in guiding therapy management in chronic liver disease. Liver biopsy is often required, but it is an invasive procedure, with a risk of severe complications (1/4000–10,000). In addition, its accuracy is prone to sampling error (6) and inter-and/or intra-observer diagnostic discrepancies occur in up to 10–20% of liver biopsies. For this reason, there is increasing interest in non-invasive methods for detecting liver fibrosis.Ultrasound-based transient elastography (TE) is one of the first non-invasive imaging methods to be used in common practice. The technique is based on low-frequency vibrations: shear waves produced by the ultrasound machine propagate through the tissue and produce an elastic deformation, with the premise that liver stiffness (LS) measurements reflect the degree of hepatic fibrosis. Displacement is reflected in the variation of the acquired echo signals. The Siemens-based ARFI system and Philips Elast PQTMuse conventional US to generate a shear wave directly within the liver tissues. This allows the sonographer to obtain both conventional US images and also specify a region of interest (ROI) for estimation of liver stiffness. The propagation velocity of the shear wave is reported in metres per second, and correlates with liver stiffness. The direct generation of shear wave within the liver tissue holds advantages over TE since it is not subject to chest/abdominal wall distortion of the waves.Results: 110 consecutive patients with liver disease underwent a liver biopsy and liver stiffness assessment by Philips EPIQ 7TMultrasound system, Siemens Acuson (ARFI) ultrasound system, 2 and Echosens FibroscanTM(currently the best-validated technique). The results of these three imaging techniques were compared with histological results.A direct, strong correlation was observed between LS values assessed by TE elastography by Elast PQ and Virtual Touch (p < 0.0001) and Metavir score.