echography


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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.

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]

echography

/echog·ra·phy/ (ĕ-kog´rah-fe) ultrasonography.

echography

(ĕ-kŏg′rə-fē)

echography

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]

ultrasonography

; echography location/measurement/image creation/delineation of deep structures by ultrasound wave deflection/transmission

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

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]

echography

ultrasonography; the use of ultrasound as a diagnostic aid. Ultrasound waves are directed at the tissues, and a record is made, as on an oscilloscope, of the waves reflected back through the tissues, which indicate interfaces of different acoustic densities and thus differentiate between solid and cystic structures.

Patient discussion about echography

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 echography
References in periodicals archive ?
Echography showed a statistically significant improvement in skin thickness in treated skin.
Ovarian atrophy can be found on abdominal echography.
Signal processing is used in telecommunications, in the transmission and analysis of satellite images, and in medical imaging (electrocardiography, electroencephalography, echography, tomography, etc.
Chest radiography and abdominal echography were normal.
Last week's echography showed nothing but a beating heart.
All participants underwent bilateral vascular echography of their femoral and carotid arteries.
A case of porocephalosis disclosed by echography during evaluation of hepatic amebiasis.
Gene duplication in 1 allele was later confirmed by the finding that 17-OH progesterone concentrations were within the reference interval in the amniotic fluid and by fetal echography showing ordinary female external genitalia.
Demonstration of nodules in the normal thyroid by echography.
and echography practitioner Greenberg note that the technique of ophthalmic ultrasound, although an important new tool in tissue evaluation and such conditions as thyroid eye disease and diagnosis of an orbital mass, is extremely operator-dependent.