ultrasonography

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ultrasonography

 [ul″trah-sŏ-nog´rah-fe]
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.

ul·tra·so·nog·ra·phy

(ŭl'tră-sŏ-nog'ră-fē),
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.
Synonym(s): echography, sonography
[ultra- + L. sonus, sound, + G. graphō, to write]
Farlex Partner Medical Dictionary © Farlex 2012

ultrasonography

(ŭl′trə-sə-nŏg′rə-fē)
n.
The use of high-frequency sound waves to image internal body structures, a developing fetus, or objects and currents that are underwater. Also called echography.

ul′tra·so·nog′ra·pher n.
ul′tra·son′o·graph′ic (-sŏn′ə-grăf′ĭk, -sō′nə-) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

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
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

ul·tra·so·nog·ra·phy

(ŭl'tră-sŏ-nog'ră-fē)
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
Synonym(s): echography, sonography.
[ultra- + L. sonus, sound, + G. graphō, to write]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

ultrasonography

(ul?tra-so-nog'ra-fe) [ ultra- + sonography]
The use of ultrasound to produce an image or photograph of an organ or tissue. Synonym: sonographyultrasonographic (son?o-graf'ik), adjective

arterial duplex ultrasonography

A diagnostic procedure that helps to identify areas within arteries where blood flow is blocked or reduced.
See: LEAS
Enlarge picture
DOPPLER ULTRASONOGRAPHY: Doppler probe used on (A) dorsal pedis and (B) posterior tibial arteries

Doppler ultrasonography

The shift in frequency produced when an ultrasound wave is echoed from something in motion. The use of the Doppler effect permits measuring the velocity of that which is being studied, e.g., blood flow in a vessel. See: illustration

endobronchial ultrasonography

Abbreviation: EBUS
The fitting of a bronchoscope with an ultrasound transducer to identify masses adjacent to the bronchi. EBUS has been used to improve the diagnostic yield of transbronchial lung biopsies and needle aspiration in patients suspected of having lung cancer and sarcoidosis.

four-dimensional ultrasonography

An ultrasonic technique, often used during pregnancy, providing images of the fetus in three dimensions and in real time. Tthe technique is called four dimensional because there are three spatial variables plus time

gray-scale ultrasonography

Sonographic B-mode scanning that permits echoes to be displayed in shades of gray according to their amplitudes.

pelvic ultrasonography

Transvaginal ultrasonography.

three-dimensional ultrasonography

, three-dimensional ultrasound, 3D ultrasonography, 3D ultrasound
An ultrasonic technique, often used during pregnancy, providing images of the fetus in three dimensions.

transrectal ultrasonography of the prostate

The use of an ultrasonic detection device placed in the rectum in order to guide biopsy of the prostate.

transvaginal ultrasonography

An ultrasonic examination of the uterus, fallopian tubes, endometrium, and, in pregnant patients, the fetus, by placing a transducer inside the vagina.

Patient care

It may be used to diagnose ectopic pregnancy, determine multiple pregnancies, locate the placenta, identify ovarian cysts and pelvic cancers, and visualize tubo-ovarian abscesses. The patient prepares for the ultrasound by removing her clothing from the waist down and dressing in a clean gown. She is helped into a supine position on an examination table, and her knees are placed in approx. 90° of flexion with her feet supported in stirrups. The ultrasound transducer is covered with a condom or sterile glove coated with a lubricant gel. The patient is told that the probe will be inserted into her vagina, and that the gel may feel cold and slippery. The probe is then directed toward the internal organs, from which sound wave (echo) images are obtained, usually painlessly and without ionizing radiation exposure.

Synonym: endovaginal ultrasound; pelvic ultrasonography
Medical Dictionary, © 2009 Farlex and Partners

ultrasonography

The use of ultrasonic waves to image body structures for diagnostic purposes. See ULTRASOUND SCANNING.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

Ultrasonography

A process that uses the reflection of high-frequency sound waves to make an image of structures deep within the body. Ultrasonography is routinely used to detect fetal abnormalities.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

ultrasonography 

A technique utilizing high frequency ultrasound waves (greater than 18 000 Hz) emitted by a transducer placed near the eye. The silicone probe, which rests on the eye, is separated from the transducer by a water column to segregate the noise from the transducer. The technique is used to make biometric measurements such as the axial length of the eye, the depth of the anterior chamber, the thickness of the lens, the distance between the back of the lens and the retina, the thickness of the cornea and detect ocular pathology. The ultrasound wave is reflected back when it encounters a change in density (or elasticity) of the medium through which it is passing. The reflected vibration is called an echo. Echoes from the interfaces between the various media of the eye are converted into an electrical potential by a piezoelectrical crystal and can be displayed as deflections or spikes on a cathode-ray oscilloscope.There are two basic techniques used for examination: a contact system (often referred to as applanation) described above in which the probe is in contact with cornea and an immersion system in which the transducer and the cornea are separated by a water bath. This latter method eliminates the risk of indentation of the cornea and underestimation of the anterior chamber depth and axial length. Two types of ultrasonographic measurements are used: (1) The time-amplitude or A-scan which measures the time or distance from the transducer to the interface and back. Thus echoes from surfaces deeper within the eye take longer to return to the transducer for conversion into electrical potential and so they appear further along the time base on the oscilloscope display. The A-scan is useful for the study of the biometric measurements, as well as measurements of intraocular tumour size (e.g. choroidal melanoma) (Fig. U1). (2) The intensity-modulated or B-scan in which various scans are taken through the pupillary area and any change in acoustic impedance is shown as a dot on the oscilloscope screen, and these join up as the transducer moves across a meridian. The B-scan is useful to indicate the position of a retinal or vitreous detachment, or of an intraocular foreign body or a tumour, and for the examination of the orbit. The B-scan is especially useful in the examination of the posterior structures of the eye when opacities prevent ophthalmoscopic examination (e.g. cataract, corneal oedema). Syn. echography. See biometry of the eye; axial length of the eye.
Fig. U1 Histogram of ultrasound reflections (or echoes) in the eye. Echoes from the various boundaries are given against total time, i.e. the time interval from the cornea to the boundary and back to the cornea. The velocity of the ultrasound waves in the eye is approximately 1550 m/s (it is 1641 m/s in the lens and 1532 m/s in the humours). In the above diagram the total time between the cornea and the retina is 32 μs. The length is then equal to 32/2 ✕ 10 −6 ✕ 1550 ✕ 10 3 = 24enlarge picture
Fig. U1 Histogram of ultrasound reflections (or echoes) in the eye. Echoes from the various boundaries are given against total time, i.e. the time interval from the cornea to the boundary and back to the cornea. The velocity of the ultrasound waves in the eye is approximately 1550 m/s (it is 1641 m/s in the lens and 1532 m/s in the humours). In the above diagram the total time between the cornea and the retina is 32 μs. The length is then equal to 32/2 ✕ 10−6 ✕ 1550 ✕ 103 = 24
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann

ul·tra·so·nog·ra·phy

(ŭl'tră-sŏ-nog'ră-fē)
The location, measurement, or delineation of deep structures by measuring the reflection or transmission of high-frequency or ultrasonic waves.
Synonym(s): echography, sonography.
[ultra- + L. sonus, sound, + G. graphō, to write]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about ultrasonography

Q. Do doctors normally do ultrasounds to prove you have mis carried?? 2 weeks ago i found out i was pregnant, i started spottion so we went to the hospital where they toldl me i miscarried, but they did not do any alternative tests to prove it not even check my Hcg levels. Im wandering if i should get a second opinion to make sure.

A. Congratulations on the new pregnancy - that's wonderful news!

Q. what does it mean when an ultrasound shows an empty amniotic sac and no baby?

A. This exact thing happened with my friend who is now 22 weeks with her first baby. She had 2 additional sacs - both empty - and the doctor said that the pregnancy had probably started out as triplets but that only one of the embryos had actually established and continued to grow.

Her doctor said it is very common for a woman to have more than one egg fertilize but that in most cases the pregnancy continues as a singleton only. She told my friend that the empty sacs would just disappear through time (which they did) and that they posed no danger to her baby.

Q. what kind of uses the medicine do with computers related to ultra sound? how does the computer helps the doctors in the ultra sound? what do the compuers use for?

A. the computers help the doctors (in ultrasound cases) to interpret/convert the ultrasound waves into a specific imaging showed in the monitor. by that a doctor can find what is normal or not inside the patient's body.
for pregnancy purposes, it really helps patient in antenatal screening to find some abnormalities (if there's any) and to monitor the fetus' development along the 9-months pregnancy.

yesterday I wrote a short article about ultrasound update : http://doctoradhi.com/blog/?p=388

More discussions about ultrasonography
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References in periodicals archive ?
A-scan comparison of reflection from the defect (dotted line) and from the interface (solid line).
Clinical advantages of optical biometers over A-scans include: negating the need for topical anaesthesia as they are non-contact; avoiding the risk of corneal injury secondary to applanation; being less challenging for the patient; and having greater precision.
The PEC A-scan response can be obtained and then the peak amplitude can be extracted.
Figure 11 shows the a-scan of line 25 before the accelerated corrosion process.
Caption: Figure 5: The A-Scan and B-Scan simulation results of the models (a), (b), (c), and (d) and the homogeneous media with the amplitude threshold at 0.003.
The frequency domain image is one of several images made by transforming the A-scans. It has a higher resolution than the time domain image and demonstrates that, among the FDI images made of a flip chip, one or more will likely have superior resolution of fine details.
With current hardware implementation, about 2048 points in sagittal plane (A-scan) are digitalized in 10 [micro]s and a maximum of 200 points in 2 ms are allowed in the transverse plane (B-scan).
At a given spatial location ([[??].sub.i]) above the ground, the time domain response recorded by the GPR unit is called an A-scan and denoted by A([[??].sub.i], t).
After taking the Fourier transform of the received signal we obtain the A-scan of the sample.
In this paper, the novel features, statistical features, and frequency domain features extracted from A-Scan data combined with SVM classifiers for material identification are tested.
From the HD SDOCT volume scans, the depth location of the retinal pigment epithelium (RPE) was automatically identified by smoothing each A-scan using a moving average filter and then detecting the two highest intensity peaks in the A-scan that corresponded to the nerve fiber layer and RPE.
The A-Scan Mode allows direct analysis of the raw signal and the real-time B-Scan Mode provides a cross-sectional view perpendicular to the scanning surface.