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Spectral Doppler: General Waveform Concepts
Jingzhi Li, MD; John Eisenbrey, PhD; Andrej Lyshchik, MD, PhD
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KEY FACTS

  • Terminology

    • Basic Imaging Considerations

      • Physiology

        TERMINOLOGY

        • Abbreviations

          • Continuous-wave Doppler (CWD)
          • Pulsed-wave Doppler (PWD)
          • Peak systolic velocity (PSV)
          • End diastolic velocity (EDV)
          • Mean velocity (MV)
        • Synonyms

          • Spectral Doppler imaging
          • Range-gated Doppler
        • Definitions

          • US images of spectral Doppler flow are obtained from measurements of movement by transmitting rapid series of US pulses
            • Echoes from stationary tissues are same from pulse to pulse
            • Echoes from moving scatters exhibit slight differences in time for signal to be returned to receiver
            • These differences in US signal are processed to produce Doppler sonogram
          • Doppler spectrum: Time vs. velocity waveform that represents variation in intravascular blood flow velocities measured using Doppler shift
          • Spectral Doppler imaging: Utilizing US waves to display blood flow velocity over time as waveform
          • Doppler effect: Perceived frequency change of sound based on movement of source of sound relative to receiver
            • Frequency perceived by receiver will be higher if source moving toward receiver and lower if source is moving away from receiver
          • 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 reflector
              • Ø is angle of incidence between US beam and direction of blood flow
              • c is speed of sound in tissue
          • 2 types of imaging can be used for Doppler shifts measurement
            • CWD
              • Simplest and oldest Doppler imaging technique
              • Uses transducer with separate receiver and transmitter so signal can be transmitted and received continuously
              • High sensitivity and not susceptible to aliasing
              • Most important drawbacks are absence of corresponding B-mode image and lack of depth resolution, making it impossible to accurately localize source of Doppler signal
            • PWD
              • Uses transducers that can transmit US pulses and measure Doppler shift sequentially within operator-defined region of interest
              • Using time-of-flight from transmission to reception of US signal, PWD can determine position from which reflected Doppler signal was produced
              • US Doppler shifts are displayed in spectral form, with frequency shifts on vertical axis and time on horizontal axis, demonstrating blood velocity as function of time
          • Pulse repetition frequency: Number of pulses of US occurring in 1 second
            • Nyquist limit = to 1/2 of pulse repetition frequency
              • Aliasing will occur when velocity exceeds Nyquist limit
          • Resistive index (RI) calculated from spectral measurements and defined as: RI = (PSV - EDV)/PSV
            • Commonly used for presenting resistance of peripheral artery
          • Pulsatility index (PI) calculated from spectral measurements and defined as: PI = (PSV - EDV)/MV
            • Used for demonstrating differences in arterial flow resistance

        IMAGING ANATOMY

        • General Anatomic Considerations

          CLINICAL IMPLICATIONS

          • Clinical Importance

            • Clinical Applications

              • Limitations

                • Diagnostic Checklist

                  Selected References

                  1. Nuffer Z et al: Spectral Doppler ultrasound of peripheral arteries: a pictorial review. Clin Imaging. 46:91-97, 2017
                  2. Kruskal JB et al: Optimizing Doppler and color flow US: application to hepatic sonography. Radiographics. 24(3):657-75, 2004
                  3. Taylor KJ et al: Doppler US. Part I. Basic principles, instrumentation, and pitfalls. Radiology. 174(2):297-307, 1990
                  4. Burns PN: The physical principles of Doppler and spectral analysis. J Clin Ultrasound. 15(9):567-90, 1987
                  Related Anatomy
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                  Related Differential Diagnoses
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                  References
                  Tables

                  Tables

                  KEY FACTS

                  • Terminology

                    • Basic Imaging Considerations

                      • Physiology

                        TERMINOLOGY

                        • Abbreviations

                          • Continuous-wave Doppler (CWD)
                          • Pulsed-wave Doppler (PWD)
                          • Peak systolic velocity (PSV)
                          • End diastolic velocity (EDV)
                          • Mean velocity (MV)
                        • Synonyms

                          • Spectral Doppler imaging
                          • Range-gated Doppler
                        • Definitions

                          • US images of spectral Doppler flow are obtained from measurements of movement by transmitting rapid series of US pulses
                            • Echoes from stationary tissues are same from pulse to pulse
                            • Echoes from moving scatters exhibit slight differences in time for signal to be returned to receiver
                            • These differences in US signal are processed to produce Doppler sonogram
                          • Doppler spectrum: Time vs. velocity waveform that represents variation in intravascular blood flow velocities measured using Doppler shift
                          • Spectral Doppler imaging: Utilizing US waves to display blood flow velocity over time as waveform
                          • Doppler effect: Perceived frequency change of sound based on movement of source of sound relative to receiver
                            • Frequency perceived by receiver will be higher if source moving toward receiver and lower if source is moving away from receiver
                          • 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 reflector
                              • Ø is angle of incidence between US beam and direction of blood flow
                              • c is speed of sound in tissue
                          • 2 types of imaging can be used for Doppler shifts measurement
                            • CWD
                              • Simplest and oldest Doppler imaging technique
                              • Uses transducer with separate receiver and transmitter so signal can be transmitted and received continuously
                              • High sensitivity and not susceptible to aliasing
                              • Most important drawbacks are absence of corresponding B-mode image and lack of depth resolution, making it impossible to accurately localize source of Doppler signal
                            • PWD
                              • Uses transducers that can transmit US pulses and measure Doppler shift sequentially within operator-defined region of interest
                              • Using time-of-flight from transmission to reception of US signal, PWD can determine position from which reflected Doppler signal was produced
                              • US Doppler shifts are displayed in spectral form, with frequency shifts on vertical axis and time on horizontal axis, demonstrating blood velocity as function of time
                          • Pulse repetition frequency: Number of pulses of US occurring in 1 second
                            • Nyquist limit = to 1/2 of pulse repetition frequency
                              • Aliasing will occur when velocity exceeds Nyquist limit
                          • Resistive index (RI) calculated from spectral measurements and defined as: RI = (PSV - EDV)/PSV
                            • Commonly used for presenting resistance of peripheral artery
                          • Pulsatility index (PI) calculated from spectral measurements and defined as: PI = (PSV - EDV)/MV
                            • Used for demonstrating differences in arterial flow resistance

                        IMAGING ANATOMY

                        • General Anatomic Considerations

                          CLINICAL IMPLICATIONS

                          • Clinical Importance

                            • Clinical Applications

                              • Limitations

                                • Diagnostic Checklist

                                  Selected References

                                  1. Nuffer Z et al: Spectral Doppler ultrasound of peripheral arteries: a pictorial review. Clin Imaging. 46:91-97, 2017
                                  2. Kruskal JB et al: Optimizing Doppler and color flow US: application to hepatic sonography. Radiographics. 24(3):657-75, 2004
                                  3. Taylor KJ et al: Doppler US. Part I. Basic principles, instrumentation, and pitfalls. Radiology. 174(2):297-307, 1990
                                  4. Burns PN: The physical principles of Doppler and spectral analysis. J Clin Ultrasound. 15(9):567-90, 1987