Transient elastography (TE) using FibroScan (Echsens, Paris, France) is a non-invasive method

of determining liver fibrosis based on the measurement of liver stiffness.1 The technique uses an ultrasound transducer probe to determine the speed of a shear wave emitted from a vibrator. The velocity of the shear wave emitted from the vibrator is proportional to tissue stiffness. TE is rapid to carry out (5–10 min), painless, and because it assesses the liver stiffness from a volume of liver tissue 1 × 4 cm (100 times the size of a core liver biopsy), it is more representative of the hepatic parenchyma. Despite these relative advantages, it is important to recognize and understand the potential limitations of this technology. To obtain a reading, the ultrasound transducer is placed signaling pathway perpendicular to the skin in an intercostal space SB203580 in the mid-axillary line with the patient lying in the supine position. Currently, three probe types are available that differ in the depth at which they assess the velocity of the shear wave (S probe, 15–50 mm; M probe 25–65 mm; XL probe 35–75 mm). The liver stiffness is reported in kiloPascals (kPa) and can range from 2.5 to 75 kPa. The validity of a FibroScan assessment is dependent on obtaining a minimum

of 10 readings, having a success rate for reading acquisitions of at least 60% and an interquartile range (IQR) to median liver stiffness ratio of less than 30%. The evidence supporting the use of TE in clinical practice is strongest for the prediction of significant fibrosis and cirrhosis in selleck chemical the chronic hepatitis C population.2 Potential future applications of this technology might extend to a role in the assessment of portal hypertension and to stratify the risk of complications

of chronic liver disease, such as varices, decompensation and development of hepatocellular carcinoma. However, as the global experience with this technology increases, it has become apparent that TE is an ineffective tool for the assessment of hepatic fibrosis among certain patient subgroups. A prospective study of 2114 FibroScan examinations identified failure to measure liver stiffness in 96 cases (4.5%).3 Body mass index (BMI) greater than 28 was identified as the only variable associated with such technical failure of liver stiffness determination. Four years later, the same group reported their experience in a prospective review of 13 369 examinations.4 Almost 1 in 5 scans was uninterpretable and, more specifically, 3.1% were measurement failures (no valid readings obtained); an additional 15.8% of results were unreliable (< 10 valid readings, an (IQR/liver stiffness measurement [LSM] greater than 30%, or a success rate less than 60%).