What is Color Doppler Flow Imaging?
Color Doppler flow imaging (CDFI), also known as two-dimensional Doppler, uses phase detection, autocorrelation processing, and color grayscale coding to average The blood flow velocity data are displayed in color and combined and superimposed on the B-mode grayscale image. It displays blood flow more intuitively, and can display the properties of blood flow and the distribution of flow velocity in the heart and blood vessels faster and more intuitively than pulse Doppler. It has unique advantages in the display of left-to-right shunt blood flow and valve regurgitation blood flow. But the quantification of blood flow is not as good as pulse wave and continuous wave Doppler.
Color Doppler flowmeter, like pulse wave and continuous wave Doppler, also uses the Doppler effect between red blood cells and ultrasound to achieve imaging. Color Doppler flowmeter includes two-dimensional ultrasound imaging system, pulse Doppler (one-dimensional Doppler) blood flow analysis system, continuous wave Doppler blood flow measurement system and color Doppler (two-dimensional Doppler) ) blood flow imaging system. The oscillator generates two quadrature signals with a difference of π/2, which are respectively multiplied by the Doppler blood flow signal. , after removing the low-frequency components generated by the vessel wall or valve, etc., it is sent to the autocorrelator for autocorrelation detection. Since each sampling contains the Doppler blood flow information produced by many red blood cells, the obtained signal is a mixed signal of multiple blood flow velocities after autocorrelation detection. The autocorrelation detection results are sent to the velocity calculator and the variance calculator to obtain the average velocity, which is stored in the digital scan converter (DSC) together with the blood flow spectrum information and two-dimensional image information after FFT processing. Finally, according to the direction and velocity of blood flow, the color processor encodes the blood flow data as pseudo-color and sends it to a color monitor for display, thereby completing color Doppler blood flow imaging.
The source of echo information obtained by color Doppler flow imaging is consistent with spectral Doppler, the distribution and direction of blood flow are displayed in two dimensions, and different velocities are distinguished by different colors. Duplex Doppler ultrasound system, which is a B-mode ultrasound image showing the location of blood vessels. Doppler measures blood flow, and this combination of B-mode and Doppler systems can more precisely locate any given blood vessel.
