Fig. 1

Classification of ultrasound techniques. From top to bottom, grayscale imaging modes provide information on organ anatomy. Doppler techniques assess flow and tissue motions (direction, velocity, and backscatter in power Doppler mode). Elastography methods provide information on mechanical properties of tissues. Quantitative ultrasound (QUS) detects sub-resolution acoustic properties to provide information on tissue microstructure. RF refers to radiofrequency data, I/Q to in-phase and quadrature data, whereas compression and shear waves refer to elastic waves used in ultrasound imaging