Could ultrasound replace radioactive dye for cancer staging?

This study tests if a special ultrasound using a contrast agent (Sonazoid) can find sentinel lymph nodes as accurately as the standard radioactive tracer method in people with melanoma, breast cancer, or head & neck cancer. About 91 adults will take part, and the goal is to see if the ultrasound method is sensitive enough to replace the radioactive approach. If successful, it could offer a safer, needle-free option for cancer staging.