Ultrasound is a very versatile imaging technique, useful for evaluating the organs and structures within the body, ligaments and tendons, superficial structures like the thyroid gland, hernias and lumps under the skin. Ultrasound is widely used to examine pregnant women (obstetrical ultrasound) and to examine the blood vessels (vascular ultrasound).
Ultrasound uses sound waves with frequencies higher than humans can hear. Ultrasound studies, also known as sonograms, are made by sending sound waves into tissues from a handheld probe. The sound waves bounce off the tissues of the body, and the echoes are sensed by the probe. The echoes are then formed into images by a computer. Ultrasound uses no X-rays.
Ultrasound is useful to help understand many conditions including:
Medical ultrasound uses the same principles to make images that bats use to find their way through the dark and to locate their food.
Dolphins, whales and sharks use ultrasound to navigate.
Studies show that sloths and gorillas use ultrasound to warn of danger.
House mice also use ultrasound to communicate.
The same principles are also integral to sonar, used to find fish, to map the bottom of the ocean for marine navigation and for military applications.
The first ultrasound images of humans were made in 1955 using repurposed machinery built to detect flaws in industrial metal.