Bookmarks
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
- Frequency change of reflected sound based on movement of source of sound relative to 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 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°
- Defined as ΔF = 2F₀V cos Ø/c
- PRF
- Number of pulses of US occurring in 1 second
- Aliasing
IMAGING ANATOMY
Anatomic Considerations
Vascular Variations Visible on Color Doppler
Physical Considerations
CLINICAL IMPLICATIONS
Clinical Importance
DIAGNOSTIC CHECKLIST
Selected References
- 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
- Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
- Wells PN: Ultrasound imaging. Phys Med Biol. 51(13):R83-98, 2006
- Szabo T. Diagnostic Ultrasound Imaging: Inside Out. 2nd ed. Oxford: Academic Press, 2014
- Allan PL et al. Clinical Doppler Ultrasound. Philadelphia: Churchill Livingstone, 2000
- Evans DH et al. Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. John Wiley & Sons Ltd., 2000
- Wells PN: Ultrasonic colour flow imaging. Phys Med Biol. 39(12):2113-45, 1994
- Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992
- Kremkau FW: Doppler color imaging. Principles and instrumentation. Clin Diagn Ultrasound. 27:7-60, 1992
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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
- Frequency change of reflected sound based on movement of source of sound relative to 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 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°
- Defined as ΔF = 2F₀V cos Ø/c
- PRF
- Number of pulses of US occurring in 1 second
- Aliasing
IMAGING ANATOMY
Anatomic Considerations
Vascular Variations Visible on Color Doppler
Physical Considerations
CLINICAL IMPLICATIONS
Clinical Importance
DIAGNOSTIC CHECKLIST
Selected References
- 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
- Rubens DJ et al: Doppler artifacts and pitfalls. Radiol Clin North Am. 44(6):805-35, 2006
- Wells PN: Ultrasound imaging. Phys Med Biol. 51(13):R83-98, 2006
- Szabo T. Diagnostic Ultrasound Imaging: Inside Out. 2nd ed. Oxford: Academic Press, 2014
- Allan PL et al. Clinical Doppler Ultrasound. Philadelphia: Churchill Livingstone, 2000
- Evans DH et al. Doppler Ultrasound: Physics, Instrumentation and Signal Processing, 2nd Ed. John Wiley & Sons Ltd., 2000
- Wells PN: Ultrasonic colour flow imaging. Phys Med Biol. 39(12):2113-45, 1994
- Kremkau FW: Doppler principles. Semin Roentgenol. 27(1):6-16, 1992
- Kremkau FW: Doppler color imaging. Principles and instrumentation. Clin Diagn Ultrasound. 27:7-60, 1992
