Probing the dynamics of tissue at low frequencies with the radiation forceof ultrasound

Over the past few years there has been an increasing interest in using the radiation force of ultrasound for evaluating, characterizing and imaging bi ological 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 held, discuss t he inter-relationship of several methods within this field and compare thei r features. The techniques in this field can be categorized into three grou ps: transient methods. shear-wave measurement methods and a recently develo ped 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.