Methods and Approaches in Ultrasound Elastography

Medical ultrasound is one of the most widely used medical imaging modalities. It allows real-time visualization of the morphology of soft tissues in the human body based on backscattered compression waves in the high-frequency (MHz) range. Special technologies are sensitive to organ functions such as blood flow and tissue strain. Over the past decades, ultrasound-based elastography (USE) has been developed and became widely applied in the clinic for the assessment of tissue stiffness in a variety of conditions including malignant tumors and liver fibrosis. The clinical benefit of USE has been overwhelmingly demonstrated in a large number of clinical studies and reviews. Unlike other sonographic methods, USE is not a single technique but rather a set of methodological concepts and approaches centered on the mechanical stimulation of soft tissues, deformation readout, and stiffness reconstruction. This chapter provides an overview of the key concepts of USE methods and their clinical applications. Many of the methods discussed are still experimental, while others have emerged as valuable clinical modalities implemented in a variety of commercial ultrasound scanners. The aim of this chapter is to guide readers through the pros and cons of individual concepts, thereby helping them to gain insight into the basic principles of USE.