Quantitative Ultrasound and Ultrasound-Based Elastography for Chronic Liver Disease: Practical Guidance, From the AJR...

Quantitative ultrasound (QUS) and ultrasound-based elastography techniques are emerging as noninvasive, effective methods for assessing chronic liver disease. They are more accurate than B-mode ultrasound alone and more accessible than MRI as alternatives to liver biopsy. Early detection and monitoring of diffuse liver processes, such as steatosis, inflammation, and fibrosis, play an important role in guiding patient management. The most widely available and validated techniques are attenuation-based QUS techniques and shear-wave elastography techniques that measure shear-wave speed (SWS). Other techniques are supported by a growing body of evidence and are increasingly becoming commercially available. This Special Series Review explains the general physical concepts of QUS and ultrasound-based elastography techniques for evaluating chronic liver disease. The article first describes QUS techniques relying on attenuation, backscatter, and speed of sound. The article then discusses ultrasound-based elastography techniques analyzing SWS, shear-wave dispersion, and shear-wave attenuation. With an emphasis on clinical implementation, each technique's diagnostic performance along with thresholds for various clinical applications are summarized to provide guidance on analysis and reporting for radiologists. Measurement methods, advantages, and limitations are also discussed. Finally, the article explores developments in quantitative contrast-enhanced and vascular ultrasound that are relevant to the evaluation of chronic liver disease.