Ultrasound uses high frequency sound waves and their echoes to scan organ structures in the body, offering safe, painless and quick diagnostic results without radiation. The technique is similar to the echolocation used by bats, whales and dolphins, as well as SONAR used by submarines. The ultrasound machine transmits high-frequency sound waves into the body. Then the machine displays the distances and intensities of the echoes it receives back on the screen, forming an image.
Ultrasound is also useful in helping physicians guide a biopsy to determine whether a breast abnormality is cancerous. Physicians use ultrasound during core and fine needle aspiration biopsies to determine where to place the needle. Ultrasound may also be used to prove whether a suspicious area is a lymph node. Lymph nodes have fatty centers which are often apparent on ultrasound images.