MSc Defence: Monitoring Focused Ultrasound Thermal Therapy using Synthetic Aperture Ultrasound Imaging with Decorrelated Compounding

Student: Michael Nguyen

Supervisors: Dr. Jahan Tavakkoli and Dr. Yuan Xu

Abstract:

Decorrelated Compounding (DC) for synthetic aperture ultrasound reduces speckle variation in images, suggesting enhanced detectability of low-contrast thermal lesions produced by Focused Ultrasound (FUS). Ex vivo porcine tissue was imaged during FUS exposure to induce a low-contrast thermal lesion and localized heating. Image quality was assessed using the Contrast-to-Noise Ratio (CNR) and the speckle SNR (sSNR). DC imaging improves sSNR and CNR up to factors of 10 and 9 respectively, in comparison to other imaging methods. The feasibility of change in backscattered energy (CBE) thermometry with DC imaging was also investigated. Measured changes in signal and backscattered energy at the focal point were consistently more precise and follow temperature profiles more closely when measured using DC imaging. These suggest that the DC method can measure subtle, temperature dependent tissue changes and can be used to monitor FUS thermal therapy.