Probing the dynamics of tissue at low frequencies with the radiation force of ultrasound.

Over the past few years there has been an increasing interest in using the radiation force of ultrasound for evaluating, characterizing and imaging biological tissues. Of particular interest are those methods that measure the dynamic properties of tissue at low frequencies. In this paper we present dynamic radiation force methods for probing tissue as a new field, discuss the interrelationship of several methods within this field and compare their features. The techniques in this field can be categorized into three groups: transient methods, shear-wave measurement methods and a recently developed method called vibro-acoustography. The last method is the focus of this paper. After briefly describing the key concepts of the first two methods, we will present a detailed description of vibro-acoustography. Finally, we will compare the capabilities and limitations of these methods.