Time-reversal focusing of therapeutic ultrasound on targeted microbubbles

Targeted microbubbles bind specifically to molecular markers of diseases and their unique acoustic signature is used to image cellular processes in vivo. The ability of time-reversal processing to focus waves through heterogeneities on such targeted microbubbles is demonstrated. For this purpose, microbubbles were deposited on a gelatin phantom and their specific signal was recorded by a high intensity ultrasonic array. The amplified time-reversed signal was re-emitted and shown to focus back in the region where the bound microbubbles were present. This proof of concept emphasizes that molecular-time-reversal focusing could guide energy deposition on early, diffuse, or metastatic disease.