Background
Diagnostic sonography or ultrasonography (US) is an imaging technique that uses high-frequency sound waves to locate internal body structures such as muscles, tendons and joints. sonography has diagnostic applications in nearly all areas of clinical medicine. In hand surgery, US is used as a first-line imaging procedure to detect soft-tissue masses, traumatic injury to ligaments or tendons in the wrist and hand, and as needle guidance during ganglion aspiration and steroid injections.1,2
Historical Overview
French physicist Pierre Curie’s discovery of piezoelectricity in 1880 is considered the first discovery of US. In 1915, French physicist, Paul Langevin developed sonographic imaging by inventing the first transducer. Interestingly, with the sinking of the Titanic in 1912, scientists were interested in methods for detecting submerged objects, especially during times of war (eg, submarines). Austrian neurologist and psychiatrist, Karl Dussik was the first physician to use US in medical diagnosis of brain tumors 1942. In 1948, American internist, George Ludwig, was the first used US to detect gallstones. Perhaps the most commonly known use of US in obstetrics and gynecology was pioneered by Ian Donald in 1958.
Description
Most modern US equipment displays the dynamic information in real time, such that the images are obtained in any plane by moving the transducer (probe). The US sound wave is typically produced by a piezoelectric transducer. Strong, short electrical pulses from the US machine drive the transducer at the desired frequency (1–18 MHz). The application of a water-based gel between the skin and the probe ensures efficient transmission of the sound wave into the body. The sound wave is partially reflected anywhere there are acoustic impedance changes in the body; some of the waves are reflected back to the transducer. The transducer translates these vibrations into electrical pulses that are then processed and transformed into a digital image displayed on the screen. The most well-known type of image is B-mode, which displays the acoustic impedance of a two-dimensional cross-section of tissue. Other types of images can display blood flow, movement of tissue or the anatomy of a three-dimensional area.
