Recent advances in noninvasive assessment of liver steatosis

Due to the steatosis epidemic, noninvasive quantification of liver fat content is of great interest. Magnetic resonance (MR) techniques, including proton MR spectroscopy (MRS) and MR chemical shift imaging can quantify liver fat by measuring, directly or indirectly (the latter), the proton density fat fraction (PDFF). They have shown excellent diagnostic accuracy and are currently the reference standard for the noninvasive assessment of liver steatosis and are used in clinical trials for evaluating the change in liver fat over time. Using ultrasound (US), three different quantitative parameters can be obtained to estimate liver fat: attenuation coefficient, backscatter coefficient, and speed of sound. Controlled attenuation parameter (CAP), which estimates the attenuation of the US beam, was the first algorithm available and is performed with a non-imaging system. Currently, several other algorithms are available on B-mode imaging ultrasound systems, and they have shown an accuracy similar to or higher than the CAP. This article reports the current knowledge about their application in patients with metabolic dysfunction-associated steatotic liver disease.