duplex ultrasonography

duplex ultrasonography,

a combination of real-time and Doppler ultrasonography. See also duplex scanner.

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ultrasonography

Ultrasound Imaging The generation of diagnostic images–sonograms–based on differences in the acoustic impedance of tissues. See Aortic ultrasonography–US, Breast US, Carotid US, Doppler US, Duplex Doppler US, Endoscopic US, Hydrocolonic US, HIFU, Ocular US, Pancreatic US, Pelvic US, Prostate US, Transcranial US Obstetrics A noninvasive technique for visualizing the gestational sac or fetus in utero.

Ultrasonography types

A-mode ultrasonography An ultrasonographic modality that provides simple displays that are plotted as a series of peaks, the height of which represents the depth of the echoing structure from the transducer

B-mode ultrasonography Brightness-modulated display Ultrasonography with a wide range of applications including imaging of a fetus, kidneys, liver, gallbladder, uterus, cardiovascular structures, breast, prostate, early ovarian CA, liver transplant recipients preoperatively–a narrow or thrombosed portal vein precludes transplant, and postoperatively to assess various complications–rejection, infection, thrombosis and patency of biliary tracts and identifying gallbladder calculi; the most common clinical use of BMU is to evaluate fetal status, providing real-time 2-D evaluation of the fetus, presenting the images in rapid succession on a monitor, and likened to a motion picture; the 'biophysical profile' has a B-mode display, and measures the head–cephalometry, thorax, abdomen, estimates fetal maturation and identifies growth retardation and major congenital anomalies, including anencephaly, hydrocephaly, meningocele, congenital heart disease, dextrocardia, fetal tumors, diaphragmatic hernia, gastroschisis, omphalocele, polycystic kidneys, hydrops fetalis, GI obstruction and death; BMU helps localize the amniocentesis needle and is of use in identifying placental anomalies including hydatidiform mole or anomalous implantation, eg placenta previa. Side effects Minimal–the energy levels for diagnostic imaging are too low to produce tissue destruction; WBCs subjected to ultrasound may mutate, ? significance

Duplex ultrasonography Ultrasonography that combines the standard real-time B-mode display with pulsed Doppler signals, allowing analysis of frequency shifts in an ultrasonographic signal, reflecting motion within a tissue, eg blood flow; DU is thus useful in evaluating ASHD of the carotid arteries, AV malformations and circulatory disturbances in the neonatal brain

M-mode ultrasonography Time-motion display A modality in which the echo signal is recorded on a continuously moving strip of paper, with the transducer is held in a fixed position over the aortic or mitral valves; each dot corresponding to a moving structure has a sinewy path, while stationary structures are represented as straight lines; M-mode was the first display used and continues to be useful for precise timing of cardiac valve opening and correlating valve motion with EKG, phonocardiography and Doppler echocardiography