Echo Made Easy - Chapter 3 Flashcards
How does colour doppler turn returning frequencies into colour-coded images?
After a burst of ultrasound is reflected back along a single scan-line, as in pulsed-wave Doppler, it is analyzed by the autocorrelator of the echo-machine. The autocorrelator compares the frequency of the returning signal with the original frequency. It automatically assigns a color-code to the frequency difference.
Analysis of several sample volumes down each scan-line and of several such scan-lines using multigate Doppler, creates a color-encoded map of the area being interrogated.
What is the colour coding convention for colour Doppler?
When are green and yellow seen?
The colours assigned to blood flow towards the transducer are shades of red white colours assigned to flow away from the transducer are hues of blue.
This is in accordance with the BART convention: Blue Away Red Towards
When blood flow at high velocity becomes turbulent, it superimposes colour variance into the colour flow map. This is seen as a mosaic pattern with shades of aquamarine, green and yellow
