Elasticity imaging techniques aim at the detection of tissue abnormalities following an external, internal or inherent mechanical stimulation. By taking advantage of the additional depth information provided by ultrasound imaging, the local tissue response (i.e., displacement, strain and/or vibration amplitude) that depends on its mechanical properties can be imaged. After introducing methods for 2D and 3D strain estimation, examples will be shown on imaging of normal and pathological myocardium in finite-element models and in vivo murine, canine and human subjects. Elasticity Imaging developed by our group also expands to Pulse Wave Imaging for the characterization of abdominal aortic aneurysms and atherosclerotic plaques in vivo, Electromechanical Wave Imaging for the assessment of the conduction properties of the myocardium and the radiation-force-based oscillatory technique of Harmonic Motion Imaging (HMI) for the characterization of breast and pancreatic tumors during tumor progression as well as after chemotherapeutic treatment.
In the second part of this lecture, therapeutic ultrasound techniques will be introduced together with application of elasticity imaging for simultaneous monitoring of the treatment procedures. Most precisely, Focused Ultrasound (FUS) for ablation of tumors substantially modifies the tissue stiffness by up to a ten-fold in order to annihilate their function. By monitoring this stiffness change, HMI can successfully detect the temperature rise and coagulation onset during treatment. An all ultrasound-based system providing simultaneous tumor detection and treatment application as well as monitoring will be described. Finally, brain applications for drug delivery through the opening of the blood-brain barrier (BBB) for brain drug delivery in conjunction with microbubbles will be shown as well as neuromodulation of both the peripheral and central nervous system.

Elisa Konofagou, Ph.D., is a Robert and Margaret Hariri Professor of Biomedical Engineering and Radiology at Columbia University.