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Power Doppler
Corinne Wessner, BS, RDMS, RVT; John Eisenbrey, PhD; Andrej Lyshchik, MD, PhD
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KEY FACTS

  • Terminology

    • Power Doppler Imaging Principles

      • Basic Imaging Considerations

        TERMINOLOGY

        • Abbreviations

          • Power Doppler imaging (PDI)
          • Power color Doppler imaging (PCDI)
        • Synonyms

          • Color Doppler energy imaging
          • Ultrasound power angiography
        • Definitions

          • Doppler effect: Frequency change from transmitting and reflected sound waves based on source relative to receiver
            • Positive frequency shift: When reflector is moving toward ultrasound beam
            • Negative frequency shift: When reflector is moving away from ultrasound beam
          • 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
              • Note that Doppler shift is highly dependent on angle of incidence and can be maximized with Ø = 0⁰ or minimized with = 90⁰
          • PDI: 1 of 3 commonly used Doppler techniques
            • Measured by strength of Doppler signal
            • Unlike color Doppler imaging (CDI), PDI is independent of velocity and direction of blood flow
            • Since there is no velocity or direction, aliasing is eliminated
            • Less dependent on angle of insonation than CDI
          • Amplitude: Strength of returning signal is dependent on density of red blood cells, sample volume, attenuation of surrounding tissue, and blood vessel in relation to sample volume size
            • Greater density of red blood cells within sample volume results in greater amplitude
          • Rouleaux effect: Cluster of red blood cells within blood vessel
            • Increased thickness (density) or cluster of red blood cells results in more reflective power Doppler signal
            • This effect is visualized mostly in central, larger vessels due to plug flow
            • Plug flow has less turbulence to disrupt clumping of red blood cell or Rouleaux flow
          • Depth: With increasing depth and attenuation, return of ultrasound signal is weaker
            • Important to use appropriate depth to optimize PDI

        IMAGING ANATOMY

        • Anatomic Considerations

          • Technical Considerations

            CLINICAL IMPLICATIONS

            • Diagnostic Checklist

              Selected References

              1. Evans DH: Colour flow and motion imaging. Proc Inst Mech Eng H. 224(2):241-53, 2010
              2. Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
              3. Evans DH et al: Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. Wiley Publishing, 2000
              4. Allan PL et al: Clinical Doppler Ultrasound Philadelphia: Churchill Livingstone, 2000
              5. Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992
              Related Anatomy
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              Related Differential Diagnoses
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              References
              Tables

              Tables

              KEY FACTS

              • Terminology

                • Power Doppler Imaging Principles

                  • Basic Imaging Considerations

                    TERMINOLOGY

                    • Abbreviations

                      • Power Doppler imaging (PDI)
                      • Power color Doppler imaging (PCDI)
                    • Synonyms

                      • Color Doppler energy imaging
                      • Ultrasound power angiography
                    • Definitions

                      • Doppler effect: Frequency change from transmitting and reflected sound waves based on source relative to receiver
                        • Positive frequency shift: When reflector is moving toward ultrasound beam
                        • Negative frequency shift: When reflector is moving away from ultrasound beam
                      • 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
                          • Note that Doppler shift is highly dependent on angle of incidence and can be maximized with Ø = 0⁰ or minimized with = 90⁰
                      • PDI: 1 of 3 commonly used Doppler techniques
                        • Measured by strength of Doppler signal
                        • Unlike color Doppler imaging (CDI), PDI is independent of velocity and direction of blood flow
                        • Since there is no velocity or direction, aliasing is eliminated
                        • Less dependent on angle of insonation than CDI
                      • Amplitude: Strength of returning signal is dependent on density of red blood cells, sample volume, attenuation of surrounding tissue, and blood vessel in relation to sample volume size
                        • Greater density of red blood cells within sample volume results in greater amplitude
                      • Rouleaux effect: Cluster of red blood cells within blood vessel
                        • Increased thickness (density) or cluster of red blood cells results in more reflective power Doppler signal
                        • This effect is visualized mostly in central, larger vessels due to plug flow
                        • Plug flow has less turbulence to disrupt clumping of red blood cell or Rouleaux flow
                      • Depth: With increasing depth and attenuation, return of ultrasound signal is weaker
                        • Important to use appropriate depth to optimize PDI

                    IMAGING ANATOMY

                    • Anatomic Considerations

                      • Technical Considerations

                        CLINICAL IMPLICATIONS

                        • Diagnostic Checklist

                          Selected References

                          1. Evans DH: Colour flow and motion imaging. Proc Inst Mech Eng H. 224(2):241-53, 2010
                          2. Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
                          3. Evans DH et al: Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. Wiley Publishing, 2000
                          4. Allan PL et al: Clinical Doppler Ultrasound Philadelphia: Churchill Livingstone, 2000
                          5. Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992