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echography |
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echography /echog·ra·phy/ (ĕ-kog´rah-fe) ultrasonography.
echography. See ultrasonography. 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.
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 ✕ 103 = 24 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 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 Q. Can anyone suggest a treatment for plantar fasciitis, apart from ultrasound, physio, anti-inflammatory agents? My friend has had Plantar Fasciitis for more than 1 year and has persevered with all the ususal treatments above plus lots of rest from weight-bearing and elevation. A. Padded foot splints, silicone heels insert and special shoes (e.g. arch-supporting shoes) may also help. These are usually sold and fitted by a professional. Exercise is another important measure. Some patients benefit from avoiding walking barefoot or in sleepers but rather using shoes from the first step. Read more or ask a question about echographyMore advanced treatments include steroid-local anesthetics injections, botulinum toxin (similar to botox) injections and surgery. The prognosis is usually favorable, and most patients achieve relief of the pain. However, all of the above is just for general knowledge - if you have any specific question, you may want to consult a doctor. You may read more here: www.nlm.nih.gov/medlineplus/ency/article/007021.htm How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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The ultrasonic echography equipment traditionally used in medical examinations is prohibitively expensive and too large to be used by health care and beauty facilities or in the home. Urologic examination, including echography and prostate-specific antigen, showed no abnormalities except a prostatic adenoma (preexisting and known to the patient). Physical examination and abdominal echography showed hepatomegaly and a huge abscess (12 cm x 10 cm x 8 cm) over the right lobe of the liver. |
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