Effectiveness of Ultrasound in Liver Stiffness and Fat Quantification

Elastography and fat quantification techniques are imaging methods integrated into the normal B-mode ultrasound. These techniques are extremely safe, with no additional risk compared to a normal ultrasound study. The advantage of using liver elastography/fat techniques to assess the degree of liver fibrosis/fatty change is that the techniques are non-invasive (no needles or biopsies) with higher patient acceptance and compliance. Shear wave elastography is a non-invasive technique that can quantify liver stiffness by measuring the speed of shear waves in the tissue of interest. Early studies have shown that the speed of the shear wave is closely associated with different stages of liver fibrosis. It has also been shown that the measurements can be reproduced by different investigators. Fatty changes, assessed by measurements called TAI, TSI, and EzHRI, are in the early stages of investigation and are proving to be robust. Early studies are mostly performed using elastography have been investigated using Fibroscan (vibration shear wave generator) techniques, and to a lesser extent using point and 2-D shearwave elastography. Fat quantification is also undertaken on the Fibroscan system, producing a Controlled Attenuation Parameter (CAP) measurement which can be correlated both to the fat quantification methods and biopsy result. The investigators have, through a previous project, demonstrated that liver stiffness, using point shear wave, on other machines can accurately identify different stages of liver fibrosis. The investigators would like to extend the study to include a further commercially available machine, namely Samsung RS85 Prestige, to study its diagnostic accuracy of point and 2-D elastography and the fat quantification techniques. As more machines with similar capabilities for stiffness and fat assessment become available, data would be collected from these also. In addition, this study will enrich scientific evidence in terms of how accurate elastography/fat assessment is as a method of measuring liver stiffness/fatty change and hopefully reduce the need to perform liver biopsy in the future.