Is FibroScan FDA Approved?
FibroScan was first introduced in the European market in 2003, China in 2008, Canada in 2009, Brazil in 2010 and Japan in 2011. Yes, FibroScan is very much US FDA (Food and Drug Administration) approved. It received its clearance from FDA on April 5, 2013. It is now available in 70+ countries. The manufacturers of FibroScan are Echosens in Paris, France.
FibroScan is a simple, rapid, non-invasive, reliable and painless diagnostic tool for assessment of severity and staging of liver fibrosis in various chronic liver diseases (fatty liver disease, hepatitis B and hepatitis C). It is used to measure tissue elastography (tissue stiffness) with the help of low-frequency ultrasound. Liver biopsy, which is an expensive, painful and invasive means for the evaluation of fibrosis and staging, has been used historically. FibroScan, using transient elastography is a safe technique that takes only about 5 to 10 minutes to complete. The patient is asked to fast for 2 to 3 hours before the procedure as there is a greater chance of increased liver stiffness due to blood flow postprandially.
FibroScan is done by placing an ultrasound transducer probe between the intercostal spaces on the right liver lobe. A low frequency (50 Hz) mild vibration is transmitted through liver tissue, which initiates an elastic shear wave. The velocity of this propagated elastic shear wave is measured through a pulse-echo ultrasound, which directly correlates to tissue stiffness and liver fibrosis. In addition to fibrosis diagnosis, FibroScan is also used for screening in liver cirrhosis, non-alcoholic steatohepatitis, hepatitis C, patient at a risk for hepatocellular carcinoma and monitoring patients who receive hepatotoxic chemotherapy.
What Are The Limitations Of FibroScan?
FibroScan that utilizes transient elastography has its own limitations. There are greater chances of failure rates and unreliable results in overweight/obese patients, children, thin patients in which different probes are used than standard probes. Liver stiffness values also differ in the cases of alanine aminotransferase elevation and acute liver inflammation. Other limitations include age, BMI, metabolic syndrome, sinusoidal congestion, steatosis, and extra hepatic cholestasis. Like any other ultrasound based technique, it is highly dependent on operator.
What Is Fibrosis And Different Stages of Liver Fibrosis?
The staging of liver fibrosis is imperative to appropriate treatment of liver disease patients. Staging is also useful in addressing patient’s response to different treatment modalities. Liver fibrosis is excessive liver scarring due to progressive liver inflammation and liver cell death in chronic liver diseases. Liver fibrosis occurs when liver tries to repair its damaged cells through deposition of new collagen fibers. This deposition of repaired tissue results in scarred tissue or fibrous tissue formation. This exaggerated wound healing response interferes with normal liver function. Liver fibrosis is caused due to various insults to liver such as hepatitis B, hepatitis C, alcohol, non-alcoholic fatty liver disease, certain drugs and toxins, trauma and biliary obstruction.
The staging of liver fibrosis determines the degree of damage afflicted to the liver. The activity or the prediction of how fibrosis is progressing is based on a popular scoring system called METAVIR scoring system. The activity grade ranges from A0 to A3: with A0 having no activity, A1 showing mild activity, A2 showing moderate activity and A3 showing severe activity.
The fibrosis staging consists of five stages fibrosis scoring system ranging from F0 to F4. F0 includes no evidence of fibrosis, F1 stage includes portal fibrosis without septa formation, F2 stage has portal fibrosis along with few septa formation, F3 staging consists of various septa without any cirrhosis, and F4 staging consists of liver fibrosis. F3 and F4 are considered the most advanced stages of liver fibrosis. Typically, FibroScan is not used for the production of exact staging; it only distinguishes mild fibrosis from more severe fibrosis.
FibroScan is a possible alternative to liver biopsy as a diagnostic tool and with other serological tests it provides a viable information and appropriate diagnosis regarding chronic liver disease and its progression and has by far reduced the requirement of invasive liver biopsies, which carries with it various complications.