Controlled Attenuation Parameter as a Noninvasive Method to Detect and Quantify Hepatic Steatosis in Chronic Liver Disease: What Is the Clinical Relevance

The gold standard for the diagnosis and quantification of hepatic steatosis has been liver biopsy. However, liver biopsy has accuracy issues due to the nonhomogeneous distribution of liver steatosis throughout the liver that imposes important sample errors. In addition, it is an invasive procedure, with an unneglectable risk of complications [5] . As such, the search for noninvasive methods to diagnose and quantify liver steatosis has been a matter of intense research in the last decade. Magnetic resonancederived techniques such as spectroscopy and measurement of proton density fat fraction are highly reliable methods, probably superior to liver histology, particularly proton density fat fraction, which allows quantification of hepatic steatosis throughout the liver [6] . However, those methods are expensive, time-consuming, and not widely available. Ultrasonography and tomography scan has similar accuracy, although the latter is more expensive and imposes exposure to radiation [7] . They have excellent accuracy for moderate-to-severe steatosis (85% sensitivity and 94% specificity). However, sensitivity decreases dramatically for steatosis <30% [8] . Ultrasonography allows subjective semiquantification of steatosis. Since recently, the elastography Fibroscan© probe can incorporate the measurement of the degree of ultrasound attenuation by hepatic fat, controlled attenuation parameter (CAP) allowing indirect quantification of liver ste