Monitoring Focused Ultrasound Thermal Therapy Using Synthetic Aperture Ultrasound Imaging With Decorrelated Compounding

Decorrelated Compounding (DC) for synthetic aperture ultrasound reduces speckle 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 lowcontrast thermal lesion and localized heating. Image quality was assessed using the Contrast-toNoise Ratio (CNR) and the speckle SNR (sSNR). DC imaging improves both the CNR and sSNR up to a factor of 9 in comparison to B-mode imaging. 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 yielded lower uncertainties 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.