Medical ultrasonography
Medical ultrasonography is an ultrasound-based imaging diagnostic technique used to visualize internal organs, their size, structure and their pathological lesions.
Ultrasonography is widely utilized in medicine, primarily in gastroenterology, cardiology, gynecology and obstetrics, urology and endocrinology. It is possible to perform diagnosis or therapeutic procedures with the guidance of ultrasonography (for instance biopsies).
Strengths of ultrasound imaging:
- It images muscle and soft tissue very well and is particularly useful for delineating the interfaces between solid and fluid-filled spaces.
- It renders "live" images, where the operator can dynamically select the most useful section for diagnosing and documenting changes, often enabling rapid diagnoses.
- It shows the structure as well as some aspects of the function of organs.
- It has no known long-term side effects and rarely causes any discomfort to the patient.
- Equipment is widely available and comparatively flexible; examinations can be performed at the bedside.
Weaknesses of ultrasound imaging:
- Ultrasound 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.
- Even in the absence of bone or air, the depth penetration of ultrasound is limited, making it difficult to image structures that are far removed from the body surface, especially in obese patients.
- The method is operator-dependent. A high level of skill and experience is needed to acquire good-quality images and make accurate diagnoses.
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 Malmö. On December 16 the same year, the method was used to generate an echo-encephalogram (ultrasonic probe of the brain). The first obstetric measurements were made in Scotland.
Echocardiography
Cardiologists can use ultrasound techniques to detect problems with the heart by recording echocardiograms. This is usually done through the chest wall (transthoracic) but can be done transesophageally (the transducer is inserted orally and passed into the esophagus). Transesophageal echocardiograms show better image quality because the ultrasound probe is closer to the heart.
The structure and movement of the heart valves can be imaged. The direction of the flow of blood can be displayed using Doppler techniques, allowing studies of flow through the heart valves.
Echocardiography was the first medical application of ultrasound.
Obstetric ultrasonography
In obstetrics, ultrasound is used to visualize the embryo or fetus in its mother's womb. In the hands of an experienced sonographer, embryos as small as 5mm in length can be visualized. In some countries, routine pregnancy ultrasound scans are performed to detect developmental defects before birth. The sex of the baby can sometimes also be identified.
All current evidence indicates that diagnostic ultrasound is safe for the unborn child, unlike radiographs, which employ ionizing radiation.
See also:
External Links
Referenced By
Animal Echolocation | Echolocation | Lund University | Medical equipment | Scan | Scanner | Scanning | Ultrasonic | Ultrasound | University of Lund
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