Since its tentative beginnings, the diagnostic imaging technique of ultrasound—which uses sound waves to visualize the body's internal organs—has found its way into most areas of medicine. Early experiments were made by Dr. George Ludwig at the Naval Medical Research Institute in Bethesda, Maryland, in the late 1940s. Ludwig successfully.-used. ultrasonics to detect human gallstones implanted in a dog.
Inge Edier (1911-2001), a Swedish cardiologist, took the idea further. He was frustrated with the inadequacies of techniques then available to examine the heart. While making decisions on heart disease prior to surgery at University Hospital Lund, he found that cardiac catheterization and contrast X-rays did not tell clinicians enough about the heart's mitral valve. He asked Carl Hertz (1920-1990), who was working in nuclear physics at Lund University, if radar might be the answer. Hertz said it was not, but he suggested ultrasonography might work instead.
After borrowing an ultrasonic reflectoscope, the men managed to get some good echoes on a screen that moved in sync with a heartbeat on October 29, 1953. Six weeks later, they used the technique to generate an ultrasonic probe of the brain. Meanwhile, in Scotland, physician lan Donald of the Glasgow Maternity Hospital was also developing the use of ultrasound for obstetric applications.
Today, ultrasound uses probes with acoustic transducers that send pulses into an organ. It is good for imaging muscle and soft tissue, and has no known long-term side effects.
