- The location, measurement, or delineation of deep structures by measuring the reflection or transmission of high frequency or ultrasonic waves. Computer calculation of the distance to the sound-reflecting or absorbing surface plus the known orientation of the sound beam gives a two-dimensional image. SEE ALSO: ultrasound. SYN: echography, sonography. [ultra- + L. sonus, sound, + G. grapho, to write]- Doppler u. application of the Doppler effect in ultrasound to detect movement of scatterers (usually red blood cells) by the analysis of the change in frequency of the returning echoes.In many settings, ultrasound has supplanted x-radiography as the imaging method of choice, because it poses no known risk to patients and is noninvasive and of moderate cost. Doppler-created ultrasound makes possible real-time viewing of tissues, blood flow, and organs that cannot be observed by any other method. It is particularly valuable in cardiology and obstetrics.- gray-scale u. the display of the ultrasound echo amplitude or signal intensity as different shades of gray, improving image quality compared to the obsolete black and white presentation.- real-time u. rapid serial ultrasound images produced using a phased array or scanning transducer; produces a video display of organ motion, such as heart valve or fetal motion.
* * *ul·tra·so·no·graph·ic -.sän-ə-'graf-ik, -.sō-nə- adj
* * *n.the use of ultrasound to produce images of structures in the human body. The ultrasound probe sends out a short pulse of high-frequency sound and detects the reflected waves (echoes) occurring at interfaces within the organs. The direction of the pulse can then be moved across the area of interest with each pulse to build up a complete image. Scans may produce a single stationary image similar to a photograph (static) or multiple sequential images similar to a video (real-time imaging). The ultrasound waves are transmitted from - and echoes detected by - piezoelectric crystals contained within the scanning probe (see transducer). As far as is known, there are no adverse effects from the use of ultrasound used at diagnostic energies. Ultrasound waves are blocked by gas, as in the lungs and bowel, which can obscure underlying structures. The detail seen increases with the frequency of the ultrasound but the depth of penetration decreases. Ultrasonography is extensively used in obstetrics (including the diagnosis of pregnancy, assessment of gestational age, diagnosis of malpresentations and hydatidiform moles, and detection of fetal abnormalities). It is also used to examine the abdominal organs, urinary tract, blood vessels, muscles, and tendons. More specialized techniques include echocardiography, transvaginal ultrasonography, transrectal ultrasonography (TRUS), intraoperative ultrasound (IOUS), endoscopic ultrasound, and transoesophageal echocardiography (TOE) examinations.
* * *ul·tra·so·nog·ra·phy (ul″trə-sə-nogґrə-fe) the visualization of deep structures of the body by recording the reflections of (echoes of) pulses of ultrasonic waves directed into the tissues. Diagnostic ultrasonography, as in echocardiography, uses a frequency range of 1 million to 10 million hertz (cycles per second), or 1 to 10 MHz. Such sound waves are transmissible only in liquids and solids. See also scan (def. 2). Called also echography and sonography. ultrasonographic adj
Medical dictionary. 2011.