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Factors Affecting Color Flow Images

Learning the basics, such as determining blood flow direction, velocity, aliasing, and laminar vs. turbulent blood flow, is just the first step in understanding CFI. Next, you must understand other factors that change the color, sensitivity, and accuracy of the image you see. These factors include: Angle dependency, which affects the accuracy of the color velocity estimates. Packet size, which affects not only the accuracy of the color velocity estimate, but also the frame rate. Color sector width, which affects the color frame rate. Color line density, which affects not only the color frame rate but also the spatial resolution of the color image. Color maps, which highlight different blood flow characteristics. Color gain, which affects the amount of the color pattern you see. Clutter filters, PRF, and transducer frequency, which allow you to optimize the color flow image. Factors Affecting Color Flow Images: Angle Dependency As in conventional Doppler, the velocity estimates produced by CFI are most accurate when the transmitted beam of sound is parallel to the blood flow. As blood flow becomes more perpendicular to the beam of sound, the resulting velocity estimates are lower than they should be, shown with a color closer to the baseline. Angle dependency is the relationship between the ultrasound beam and the blood flow angle, and the resulting change in velocity estimates accuracy. This illustration demonstrates the concept of angle dependency within a tubular structure with flow from left to right.