Radiation force localization of HIFU therapeutic beams coupled with magnetic resonance-elastography treatment monitoring in vivo application to the rat brain

Magnetic resonance elastography is feasible in the brain and is a new way to non invasively control the stiffness of the tissue. The thermal HIFU necrosis of the brain results in an increase of its complex shear modulus. Furthermore, MR sequences can be very sensitive to motion and thus give a good tool to detect the acoustic radiation force in in-vivo. This target control can be very valuable in order to assess the quality of the aberration correction when a high power US signal is about to be sent trough the skull. In this context, ex-vivo and in-vivo experiments were conducted with and without an aberrating skull. They confirmed that both the MR localization of the US focal point and the measurement of the tissue stiffness pre and post HIFU, together with temperature control during HIFU are valuable and feasible techniques for the accurate monitoring of HIFU in the brain.