Elastography: ultrasonic estimation and imaging of the elastic properties of tissues

The basic principles of using sonographic techniques for imaging the elasti c properties of tissues are described, with particular emphasis on elastogr aphy. After some preliminaries that describe some basic tissue stiffness me asurements and some contrast transfer limitations of strain images are pres ented, four types of elastograms are described, which include axial strain, lateral strain, modulus and Poisson's ratio elastograms. The strain filter formalism and its utility in understanding the noise performance of the el astographic process is then given, as well as its use for various image imp rovements. After discussing some main classes of elastographic artefacts, t he paper concludes with recent results of tissue elastography in vitro and in vivo.