real-time ultrasonography

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Related to real-time ultrasonography: A-mode ultrasound


a radiologic technique in which deep structures of the body are visualized by recording the reflections (echoes) of ultrasonic waves directed into the tissues. adj., adj ultrasonograph´ic.
in the nursing interventions classification, a nursing intervention defined as performance of ultrasound exams to determine ovarian, uterine, or fetal status.  Frequencies in the range of 1 million to 10 million hertz are used in diagnostic ultrasonography. The lower frequencies provide a greater depth of penetration and are used to examine abdominal organs; those in the upper range provide less penetration and are used predominantly to examine more superficial structures such as the eye.

The basic principle of ultrasonography is the same as that of depth-sounding in oceanographic studies of the ocean floor. The ultrasonic waves are confined to a narrow beam that may be transmitted through or refracted, absorbed, or reflected by the medium toward which they are directed, depending on the nature of the surface they strike.

In diagnostic ultrasonography the ultrasonic waves are produced by electrically stimulating a crystal called a transducer. As the beam strikes an interface or boundary between tissues of varying density (e.g., muscle and blood) some of the sound waves are reflected back to the transducer as echoes. The echoes are then converted into electrical impulses that are displayed on an oscilloscope, presenting a “picture” of the tissues under examination.

Ultrasonography can be utilized in examination of the heart (echocardiography), in location of aneurysms of the aorta and other abnormalities of the major blood vessels, and in identifying size and structural changes in organs in the abdominopelvic cavity. It is, therefore, of value in identifying and distinguishing cancers and benign cysts. The technique also may be used to evaluate tumors and foreign bodies of the eye, and to demonstrate retinal detachment. Ultrasonography is not, however, of much value in examination of the lungs because ultrasound waves do not pass through structures that contain air.

A particularly important use of ultrasonography is in the field of obstetrics and gynecology, where ionizing radiation is to be avoided whenever possible. The technique can evaluate fetal size and maturity and fetal and placental position. It is a fast, relatively safe, and reliable technique for diagnosing multiple pregnancies. Uterine tumors and other pelvic masses, including abscesses, can be identified by ultrasonography.
A-mode ultrasonography that in which on the cathode-ray tube display one axis represents the time required for the return of the echo and the other corresponds to the strength of the echo.
B-mode ultrasonography that in which the position of a spot on the CRT display corresponds to the time elapsed (and thus to the position of the echogenic surface) and the brightness of the spot to the strength of the echo; movement of the transducer produces a sweep of the ultrasound beam and a tomographic scan of a cross section of the body.
Doppler ultrasonography that in which measurement and a visual record are made of the shift in frequency of a continuous ultrasonic wave proportional to the blood-flow velocity in underlying vessels; used in diagnosis of extracranial occlusive vascular disease. It is also used in detection of the fetal heart beat or of the velocity of movement of a structure, such as the beating heart.
Normal versus abnormal Doppler arterial waveform patterns. A, Normal waveform with triphasic pattern of sharp upstroke and downstroke and good amplitude: (1) systolic component, (2) diastolic component, and (3) elastic wall rebound. B, Abnormal waveform with monophasic pattern of low amplitude and flat waves. This pattern indicates severe arterial obstruction. From Malarkey and McMorrow, 2000.
gray-scale ultrasonography B-mode ultrasonography in which the strength of echoes is indicated by a proportional brightness of the displayed dots.
real-time ultrasonography B-mode ultrasonography using an array of detectors so that scans can be made electronically at a rate of 30 frames a second.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

real-·time ul·tra·so·nog·ra·phy

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.
Farlex Partner Medical Dictionary © Farlex 2012
References in periodicals archive ?
Stokes CA (1988) Real-time ultrasonography for determining pregnancy status and viable fetal numbers in ewes.
The use of real-time ultrasonography with high-frequency transducers can significantly improve the evaluation of patients with neck masses.
Transcutaneous ultrasonography (TUS) of the ovaries was performed by a real-time ultrasonography using a convex linear transducer 5MHz (Aloka[R] SSD 500, Aloka Co.
Real-time ultrasonography for early pregnancy detection in goats has been performed either transrectally or transabominally (Padilla-Rivas et al.
These results indicate that real-time ultrasonography provides a rapid and highly accurate method of pregnancy detection as early as 22 d.

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