Ultrasound elastomicroscopy using water beam indentation: Preliminary study

This study is aimed towards developing a novel noncontact ultrasonic indentation system for measuring or imaging quantitative mechanical properties of soft tissues, which are increasingly important for tissue assessment and characterization. The key idea of this method is to use a water beam as an indenter to stimulate the soft tissue. The water beam also serves as a medium for an ultrasound beam propagating through. The application of water beam benefits the system to use focused high-frequency ultrasound without any additional attenuation. The indentation deformation was estimated from the ultrasound echoes using cross-correlation algorithm and the indentation force was calculated from the measured pressure and an overall force. Experiments were performed on tissue-mimicking phantoms whose Young's moduli and Poisson's ratio were measured using uniaxial compression and the indentation pressure/deformation curves were obtained. This system shows good ability in measuring the phantoms with different stiffness. It is expected that this novel water beam indentation method can be used to construct an ultrasound elastomicroscopy for imaging tissue's elasticity in a high resolution.