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Color Doppler
Michael R. Kramer, MD; Corinne Wessner, BS, RDMS, RVT; John Eisenbrey, PhD
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KEY FACTS

  • Terminology

    • Anatomy Imaging Issues

      • Physiology

        • Basic Imaging Considerations

          TERMINOLOGY

          • Synonyms

            • Color flow imaging (CFI)
          • Definitions

            • Aliasing
              • Ambiguity in Doppler shift frequency information when true Doppler shift exceeds 1/2 pulse repetition frequency (PRF)
            • Color Doppler US
              • Approximates mean velocity and direction of flow within vessel or tissue through color coding, superimposing this color onto vessels in grayscale image
            • Color coding represents direction of flow in relation to transducer
              • By default, blood flow coming toward transducer is red
              • By default, blood flow going away from transducer is blue
                • Important to remember that color coding can be changed by user
            • Doppler effect
              • Frequency change of reflected sound based on movement of source of sound relative to receiver
                • Frequency perceived by receiver will be higher if source moving toward receiver
                • Frequency perceived by receiver will be lower if source moving away from receiver
                • Differences in transmitted vs. perceived frequencies from blood scatters can be used to quantify direction, magnitude, or intensity of blood flow
            • Doppler shift: Difference between transmitting and reflected frequency emitted from transducer
              • Defined as ΔF = 2F₀V cos Ø/c
                • ΔF is Doppler shift
                • F₀ is transmit frequency
                • V is velocity of blood flow
                • Ø is angle of incidence between US beam and direction of blood flow
                • c is speed of sound in tissue
                • Notice that Doppler shift is highly dependent on angle of incidence and can be maximized with Ø = 0° or minimized with Ø = 90°
            • PRF
              • Number of pulses of US occurring in 1 second

          IMAGING ANATOMY

          • Anatomic Considerations

            • Vascular Variations Visible on Color Doppler

              • Physical Considerations

                CLINICAL IMPLICATIONS

                • Clinical Importance

                  • DIAGNOSTIC CHECKLIST

                    Selected References

                    1. Jenssen C et al: [Ultrasound artifacts and their diagnostic significance in internal medicine and gastroenterology - part 2: color and spectral Doppler artifacts.] Z Gastroenterol. 54(6):569-78, 2016
                    2. Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
                    3. Wells PN: Ultrasound imaging. Phys Med Biol. 51(13):R83-98, 2006
                    4. Szabo T. Diagnostic Ultrasound Imaging: Inside Out. 2nd ed. Oxford: Academic Press, 2014
                    5. Allan PL et al. Clinical Doppler Ultrasound. Philadelphia: Churchill Livingstone, 2000
                    6. Evans DH et al. Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. John Wiley & Sons Ltd., 2000
                    7. Wells PN: Ultrasonic colour flow imaging. Phys Med Biol. 39(12):2113-45, 1994
                    8. Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992
                    9. Kremkau FW: Doppler color imaging. Principles and instrumentation. Clin Diagn Ultrasound. 27:7-60, 1992
                    Related Anatomy
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                    References
                    Tables

                    Tables

                    KEY FACTS

                    • Terminology

                      • Anatomy Imaging Issues

                        • Physiology

                          • Basic Imaging Considerations

                            TERMINOLOGY

                            • Synonyms

                              • Color flow imaging (CFI)
                            • Definitions

                              • Aliasing
                                • Ambiguity in Doppler shift frequency information when true Doppler shift exceeds 1/2 pulse repetition frequency (PRF)
                              • Color Doppler US
                                • Approximates mean velocity and direction of flow within vessel or tissue through color coding, superimposing this color onto vessels in grayscale image
                              • Color coding represents direction of flow in relation to transducer
                                • By default, blood flow coming toward transducer is red
                                • By default, blood flow going away from transducer is blue
                                  • Important to remember that color coding can be changed by user
                              • Doppler effect
                                • Frequency change of reflected sound based on movement of source of sound relative to receiver
                                  • Frequency perceived by receiver will be higher if source moving toward receiver
                                  • Frequency perceived by receiver will be lower if source moving away from receiver
                                  • Differences in transmitted vs. perceived frequencies from blood scatters can be used to quantify direction, magnitude, or intensity of blood flow
                              • Doppler shift: Difference between transmitting and reflected frequency emitted from transducer
                                • Defined as ΔF = 2F₀V cos Ø/c
                                  • ΔF is Doppler shift
                                  • F₀ is transmit frequency
                                  • V is velocity of blood flow
                                  • Ø is angle of incidence between US beam and direction of blood flow
                                  • c is speed of sound in tissue
                                  • Notice that Doppler shift is highly dependent on angle of incidence and can be maximized with Ø = 0° or minimized with Ø = 90°
                              • PRF
                                • Number of pulses of US occurring in 1 second

                            IMAGING ANATOMY

                            • Anatomic Considerations

                              • Vascular Variations Visible on Color Doppler

                                • Physical Considerations

                                  CLINICAL IMPLICATIONS

                                  • Clinical Importance

                                    • DIAGNOSTIC CHECKLIST

                                      Selected References

                                      1. Jenssen C et al: [Ultrasound artifacts and their diagnostic significance in internal medicine and gastroenterology - part 2: color and spectral Doppler artifacts.] Z Gastroenterol. 54(6):569-78, 2016
                                      2. Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
                                      3. Wells PN: Ultrasound imaging. Phys Med Biol. 51(13):R83-98, 2006
                                      4. Szabo T. Diagnostic Ultrasound Imaging: Inside Out. 2nd ed. Oxford: Academic Press, 2014
                                      5. Allan PL et al. Clinical Doppler Ultrasound. Philadelphia: Churchill Livingstone, 2000
                                      6. Evans DH et al. Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. John Wiley & Sons Ltd., 2000
                                      7. Wells PN: Ultrasonic colour flow imaging. Phys Med Biol. 39(12):2113-45, 1994
                                      8. Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992
                                      9. Kremkau FW: Doppler color imaging. Principles and instrumentation. Clin Diagn Ultrasound. 27:7-60, 1992