A novel ultrasonic technique for differentiating cysts from solid lesions: preliminary results in the breast.

The feasibility of a new ultrasonic technique to distinguish cysts from solid lesions is explored. High intensity pulses are used to induce acoustic streaming in cyst fluid, and this motion is detected using Doppler techniques. Acoustic streaming cannot be generated in solid lesions, therefore, its detection would indicate a cyst. In six of seven breast cysts motion was clearly generated and detected in vivo. Ultrasonic pulses with intensities up to 4.4 W cm-2 (I(spta) in water) were focused on the cysts for 10 s. Lesion diameters ranged from 0.6 to 2.5 cm; induced flow velocities were less than 4.0 cm s-1.