Real-time imaging of tissue vibration using a two-dimensional speckle tracking system

Tumors in soft tissues are often detected because of their higher stiffness relative to surrounding tissues. A number of groups have constructed systems which attempt to estimate stiffness by imaging the propagation of low frequency (<1 KHz) mechanical waves using modified one-dimensional flow measurement techniques. We have constructed a system which utilizes a two-dimensional speckle tracking technique to measure vibrations in soft tissues in real-time. The vibration source and speckle tracking system are completely synchronous, so phase information is preserved. We describe the system and present the results of initial calibration studies