Clinical approaches to echocardiographic tissue characterisation

Abstract

Ultrasonic tissue characterisation aims at gaining information about the physical properties of structures under examination rather than simply registering their position and motion. This additional information comes from determining characteristics of echoes beyond those related to the time at which they return to the transducer, in order to gain an idea as to how the ultrasound has been modified during its passage through the tissues. A number of such characteristics have been used, including those of individual echoes such as amplitude, phase, or frequency content, or those involving a statistical analysis of the distribution of some property over the image, a process referred to as texture analysis. Tissue characterisation thus depends to a much greater extent than simple image generation on quantification of ultrasound. In addition, if it is to be anything other than an empirical endeavour, the physical properties of the tissues, the nature of their interaction with ultrasound and the transfer function of the system used to generate and record the ultrasound must all be characterised. As will be seen, each of these stages give rise to conceptual and practical problems.