ultrasound systems by combining anatomical 2-D imaging with proprietary real-time stimulation paradigms to image, detect, locate in 3-D, and classify micron-size target(s) - previously conceived to be outside of conventional ultrasound capabilities - based on their unique response signature(s). Quantason's technology is sensitive to tissue characteristics and material properties which are clinically associated with disease states, such as markers of breast premalignant lesions (clusters and grouped microcalcifications), which may not be visible in traditional ultrasonic and mammographic images.