How to Measure and Assess Liver Fibrosis: Endorsement of the Use of Vibration-Controlled Transient Elastography

Kurt J. Isselbacher


AccessMedicine from McGraw-Hill 

Hepatic fibrosis is the common result of injury to the liver from a variety of damaging mechanisms, and the accurate assessment of the degree of fibrosis is clinically important. For many years examination of hepatic histopathology has been considered the gold standard to assess liver fibrosis. However, liver biopsy is invasive and in many instances reluctantly used by physicians and patients. Now, after many years of evaluation, the noninvasive technique of vibration-controlled transient elastography (VCTE) appears to be the approach of choice and has been endorsed by the American Association for the Study of Liver Diseases.

Transient elastography is an ultrasound-based technology that involves acquisition of pulse-echo ultrasound signals to measure liver stiffness. It involves using the tip of an ultrasound transducer probe placed between the ribs over the right lobe of the liver. The probe transmits a lower-amplitude vibration and frequency signal to the liver, which in turn induces an electric shear wave that propagates throughout the liver tissue. The pulse-echo ultrasound allows measurement of wave velocity (in meters per second), which correlates with measurement of liver stiffness (in kilopascals). Normal liver stiffness is reported to be in the range of 4–6 kPa, whereas in cirrhosis the levels are generally >12–14 kPa (Rockey 2008).

There are five key features of VCTE:

  1. It is technically easy to perform and reproducible in >95% of patients;

  2. It is safe and relatively inexpensive (particularly when compared with liver biopsy);

  3. It correlates very well with the degree of hepatic fibrosis;

  4. It has utility in patients with hepatitis C and other liver diseases; and

  5. High levels of liver stiffness correlate well with subsequent clinical complications and even with the risk of developing hepatocellular carcinoma.

Thus, VCTE has the potential to revolutionize the care of patients with chronic liver disease by improving the management of their disease and lowering the cost of their care.