Transient Elastography (Fibroscan®): A New Look of Liver Fibrosis and Beyond

Abstract

It is now indispensable to assess the severity of liver fibrosis in essentially all chronic liver diseases in order to determine the prognosis, the need of treatment, as well as monitor disease progression and response to treatment. Liver biopsy is limited by its invasiveness and patient acceptability. Transient elastography (TE, Fibroscan ®) is a noninvasive tool with satisfactory accuracy and reproducibility to estimate liver fibrosis. TE has been well validated in all major liver diseases namely chronic hepatitis B (CHB) and C, nonalcoholic fatty liver disease (NAFLD), alcoholic liver disease, primary biliary cirrhosis and primary sclerosing cholangitis. As alanine aminotransferase (ALT) is one of the major confounding factors of liver stiffness in CHB, an ALT-based algorithm has been developed and higher liver stiffness measurements (LSM) cutoff values for different stages of liver fibrosis should be used in patients with elevated ALT levels. Falsely high LSM results well within cirrhotic range may occur during ALT flare, such that TE should not be used in patients with serum ALT level above five times of the upper limit of normal. TE is also useful in predicting patient prognosis such as development of hepatocellular carcinoma (HCC), portal hypertension, postoperative complications in HCC patients, and also survival. Unfortunately, failed acquisition of TE is common in obese patients. The new XL probe, a larger probe with lower ultrasound frequency and deeper penetration, increases the success rate of TE in obese patients. The median LSM value with XL probe was found to be lower than that by the conventional M probe, hence lower LSM cutoff values may be warranted. On the other hand, a novel ultrasonic controlled attenuation parameter (CAP) of the machine is currently under the evaluation and it is a potentially useful parameter as a noninvasive and objective method to detect and quantify hepatic steatosis.