Diffuse liver disease is one of the major health problems in the world. It can result from many causes, including viral hepatitis (Hepatitis B or Hepatitis C), non-alcoholic or alcoholic fatty liver disease, autoimmune hepatitis, drug-induced liver injury, primary biliary cirrhosis, and several other less frequent etiologies.
It is estimated that 360 million and 180 million people worldwide are infected with viral hepatitis B and C respectively. Between 500,000 and 700,000 people die annually as a result of Hepatitis B virus infection, and more than 350,000 people are estimated to die each year from Hepatitis C-related liver disease. Chronic liver damage results in hepatic fibrosis, characterized by an increase in extracellular matrix material produced by fibroblast-like cells.
This process results in liver fibrosis that can progress to cirrhosis with distortion of normal liver architecture and portal hypertension. According to the Society of Radiologists in Ultrasound (SRU) consensus, in select patients, elastography may eliminate the need for liver biopsy for staging fibrosis.
Accurately staging the degree of liver fibrosis is extremely important to determine if antiviral therapy is appropriate, and to predict treatment outcome and malignant potential. With current drug therapy, early stage fibrosis may be reversible.
The histologic evaluation of liver biopsies is carried out using scoring systems that produce values for various categories of inflammation (grade), and fibrosis (stage). There are several scoring systems, all categorizing similar features. In the assessment of chronic Hepatitis C Virus (HCV), the most reproducible scoring system is the Metavir. On the Metavir scoring system, liver fibrosis is evaluated semi-quantitatively and staged on a five-point scale from 0 to 4 (F0: absent; F1: enlarged fibrotic portal tract; F2: peri-portal or initial portal-portal septa but intact architecture; F3: architectural distortion but no obvious cirrhosis; and F4: cirrhosis).
The gold standard for diagnosis and staging of liver fibrosis has been liver biopsy. In addition to being an invasive procedure with potential complications of bleeding and severe pain, biopsy sampling error is an intrinsic problem due to the small sample size in a heterogeneous process.