Medical ultrasonography

Medical ultrasonography is an ultrasound-based imaging diagnostic technique used to visualize internal organs, their size, structure and their pathological lesions. It is particularly useful in delineating the interfaces between solid and cystic spaces.

Ultrasonography is widely utilized in medicine, primarily in gastroenterology, cardiology, gynecology and obstetrics, urology and endocrinology. It is possible to perform diagnostic or therapeutic procedures with guidance of ultrasonography display (for instance biopsy).

Ultrasound is good in scanning muscle and soft tissue. It cannot penetrate bone and performs poorly when there is air between the scanner and the organ of interest. For example, overlying gas in the gastrointestinal tract often makes ultrasound scanning of the pancreas difficult.

Table of contents

1 History
2 Echocardiography
3 Obstetric ultrasonography
4 Treatment
5 External Links

History

Medical ultrasonography was invented in 1953 at Lund University by cardiologist Inge Edler and Carl Hellmuth Hertz, the son of Gustav Ludwig Hertz, who was a graduate student at the department for nuclear physics.

Edler had asked Hertz if it was possible to use radar to look into the body, but Hertz said this was impossible. However, he said, it might be possible to use ultrasonography. Hertz was familiar with using ultrasonic reflectoscopes for nondestructive materials testing, and together they developed the idea of using this method in medicine.

The first successful measurement of heart activity was made on October 29, 1953 using a device lent from the ship construction company Kockums in Malm�. On December 16 the same year, the method was used for echo-encefalogram (ultrasonographic measurement into the brain). The first obstetric measurements were made in Scotland.

Echocardiography

Cardiologists can use ultrasound techniques to detect problems with the heart. This is known as an echocardiogram. This is usually done through the chest (transthoracic) but sometimes it is necessary to perform the echocardiogram transesophageally (detecting device is inserted orally and passed into the esophagus). Transesophageal echocardiograms deliver better images because the ultrasound probe is closer to the heart.

Movement of the heart valves, and any vegetations growing on them can be established. The direction of the flow of blood can be displayed using doppler techniques, allowing studies of flow through the heart valves.

This was the first way ultrasound echoes was used for medical purposes.

Obstetric ultrasonography

In obstetrics, ultrasound is used to visualise the baby in the womb. In the hands of an experienced sonographer, a fetus as small as 5mm in length can be visualised in the uterus. Routine pregnancy ultrasound scans are performed, usually 18-20 weeks into the pregnancy, to detect developmental defects in utero. The sex of the baby can sometimes also be identified. Ultrasound is believed to be harmless, unlike radiographs that use x-ray radiation.

Treatment

Ultrasound can also be used to treat patients. With gallstones, or kidney and bladder stones, the stone can not only be visualised, but high frequency sounds can be used to fragment and demolish it, so it can then pass out of the body naturally. This effect is achieved by focusing several ulstrasound transmitters on the stone, finding the resonance frequency of the stone and destroying it with and intense sound at this frequency. This is roughly the same effect that is observed when a high-pitched sound destroys a crystal glass by resonance.