Molecular focusing of high-intensity ultrasound: Time-reversal focusing applied to targeted ultrasound contrast agents

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 reemitted 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.