Ultrasound color doppler, also known as color ultrasound, is a medical device used for ultrasound examination of organs in various parts of the body, especially for diagnoses of the heart, limb blood vessels, superficial organs, abdominal cavity, obstetrics and gynecology.
Ultrasound color doppler works by introducing color Doppler technology on the basis of high-definition black and white B-mode ultrasound. The colour flow doppler ultrasound can form color Doppler ultrasound blood flow images, which have the advantages of two-dimensional ultrasound structural images while providing rich information on hemodynamics, and are known as "non-invasive vascular angiography" in clinical practice.
The color Doppler flow imaging technology displays blood flow signals in colors, with pseudocolor encoding composed of red, blue and green basic colors. The red color is set to represent the blood flow towards the probe and the blue color represents the blood flow away from the probe. The blood flow velocity is related to the color brightness, with high velocities having bright colors and low velocities having weak colors. For example, when the blood flow velocity towards the probe is low, the signal is dark red, and when the blood flow velocity away from the probe is low, the signal is dark blue. When the blood flow velocity is very low, the brightness of the color signal is weak, making it difficult to distinguish from the screen. In this case, a color enhancer is added to improve the brightness of the color signal for low-speed blood flow.
For accurate and rapid expression of blood flow velocity, sometimes three colors are used to represent the speed, with a gradually brighter red signal that represents the blood flow towards the probe. If the blood flow is faster, it changes from red to yellow, and then to green, and three colors coexist to represent different flow velocities. Cyan and green are used to represent the faster blood flow away from the probe.
Ultrasound color doppler instruments, such as the handheld vascular doppler ultrasound, have two color modes: one is used for blood flow detection outside the cardiovascular system, with only red, yellow, blue and cyan colors; the other is used for blood flow detection within the cardiovascular system, with two to three colors in each direction.
Ultrasound machine has only one probe and can generally only examine abdominal organs, while color ultrasound has three probes and can also examine the heart, skin surface, blood vessels, tumors and others besides the abdomen.
The main technical indicators of color Doppler ultrasound are much higher than those of B-mode ultrasound (such as the number of probe crystals, imaging channel numbers, imaging dynamic range, host processing power and speed, etc.), which can significantly improve image resolution, detect smaller lesions at an earlier stage, and increase the early diagnosis rate of diseases, as well as show the details of changes in lesions around and inside.
Ultrasound colour doppler has the ability of color Doppler blood flow imaging, which can display the changes in the anatomical structure, blood flow direction, blood flow velocity and blood flow state of the lesion area, greatly improving the ability to differentiate diseases and the accuracy of diagnosis.
Ultrasound colour doppler has the function of tissue harmonic imaging, which can significantly reduce the interference of obesity, gas and other artifacts, and improve image clarity.
Ultrasound colour doppler has the function of contrast harmonic imaging, which can perform acoustic imaging and conduct more in-depth examination and research on lesions.