Streaming detection: improvements in sensitivity

Streaming detection is a new ultrasonic technique proposed to distinguish fluid-filled lesions, or cysts, from solid lesions in the breast. In this technique, high intensity ultrasound pulses are used to induce acoustic streaming in cyst fluid, and this motion is detected using flow estimation methods. Results from a pilot clinical study were presented previously in which acoustic streaming was successfully induced and detected in six of seven known cystic lesions in vivo. However, the detected velocities were fairly slow (less than 4 cm/sec), and in some cases the velocities were only detected intermittently. We have conducted finite element simulations and phantom experiments with the goal of increasing the induced acoustic streaming velocity while minimizing patient exposure. Parameters that have been studied include: intensity, transmit aperture size and cyst diameter. We have also investigated the use of clutter filters with optimal slow flow detection capabilities. Results from these studies are presented along with their implications for future implementation of streaming detection.