Monitoring formation of high intensity focused ultrasound (HIFU) induced lesions using backscattered ultrasound

Backscattered radio frequency (RF) data collected in a series of in vitro experiments, in which HIFU lesions were created in bovine liver tissue, were analyzed using two signal processing approaches to visualize temporal evolution of lesion formation. Change in round-trip travel time provides information related to temperature change during and after therapy. Changes in the RF spectrum related to changes in scattering properties of the heated region were observed before visible changes appeared on B-mode images. Effect of increased attenuation in the necrosed tissue region was also observed. Results demonstrate potential for these two techniques in image-guided HIFU therapy.