Doppler Imaging

Published on 06/02/2015 by admin

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Last modified 06/02/2015

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8 Doppler Imaging

The Doppler shift is the change in frequency of sound when the sound wave strikes a moving object. This means the frequency of the transmitted and reflected sound waves is not the same. Doppler shifts in clinical imaging are in the audible range (±10 KHz). Red blood cells are the primary reflectors that produce Doppler shifts. Ultrasound machines can color-encode the mean velocity (color Doppler), variance within the sample volume (variance Doppler), and power spectrum of the frequency shift (power Doppler).1

The optimal spectral Doppler angle is 30 to 60 degrees. Doppler angles greater than 60 degrees result in small Doppler shifts. Doppler angles less than 30 degrees result in loss of signal due to refraction.

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