Two dimensional shear wave elastography-Basic principles and current applications

Ultrasound-based elastography techniques are increasingly available on modern ultrasound systems. The application of elastography extends the utility of ultrasound, yielding new information about the impact of disease on tissue biomechanics. By modifying the B-mode imaging pulse, an Acoustic Radiation Force Impulse produces shear waves in selected tissue. Quantifying the speed of the resultant shear wave provides an indirect assessment of tissue stiffness, with stiffer tissue producing faster shear wave movement than softer tissue. Two main types of ultrasound shear wave elastography are currently in use. Point shear wave elastography uses one or two pulses to measure shear wave speeds over a small fixed area. Alternatively, two-dimensional shear-wave elastography provides a colour elastogram map over a larger area, allowing the operator to select specific regions of interest to measure shear wave speed. This article will discuss the essential physics principles, and clinical uses of two-dimensional shear wave elastography, aiming to provide sonographers with a basic understanding of the technology and current applications.