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2264 pages added, reviewed or updated during the last month (last updated: 21/4/2021)


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doppler ultrasonography (assessment of carotid arteries)

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Doppler ultrasonography may be used to assess the patency of both intracranial and extracranial vessels.

Either a continuous wave or a pulsed system is used. The latter may be interfaced with B mode scanning to provide a duplex scan. This provides additional information to the continuous wave regarding plaque morphology. Colour coded doppler is also available; flow away from the transducer is blue, towards it it red, and flow velocity is proportional to colour saturation. It is especially useful in pseudo-occlusion for example, high grade carotid stenosis may be misinterpreted as total occlusion with standard methods.

Frequencies of 5-10 MHz are typical in extracranial ultrasonography. A lower frequency, 2 MHz, is more usual in intracranial ultrasound.

One major disadvantage of doppler ultrasonography as a whole is operator dependence. At least 6 months must be spent training before reliable data can be obtained.

Last reviewed 01/2018

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