Oelze - ECE 571 Lecture 4Oelze - ECE 571 Lecture 4

Biological Measurement 1Biological Measurement 1

BIOE 571BIOE 571

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I. Topics Covered TodayI. Topics Covered Today

• Detecting the envelope of a signalDetecting the envelope of a signal• B-mode image construction: a recipeB-mode image construction: a recipe• Characterizing B-mode image qualityCharacterizing B-mode image quality

• Methods for improving B-mode imagingMethods for improving B-mode imaging

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Doppler CircleDoppler Circle

ffS S

Assume a sound source emitting sound with frequency fAssume a sound source emitting sound with frequency fSS is is moving with respect to the observer moving with respect to the observer

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Doppler CircleDoppler Circle

ffS S

Assume a sound source emitting sound with frequency fAssume a sound source emitting sound with frequency fSS is is moving with respect to the observer moving with respect to the observer

x x ΔΔf = ff = fssccss/c/c00 ΔΔf = -ff = -fssccss/c/c00

ΔΔf = 0 f = 0

ΔΔf = ff = fssccsscoscosθθ/c/c00

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Ultrasound DopplerUltrasound Doppler

Doppler shift in ultrasound is in audible ranges Doppler shift in ultrasound is in audible ranges

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Ultrasound Doppler: CWUltrasound Doppler: CW

Blood velocity Blood velocity

θθ

Observation on Observation on overlap of beams overlap of beams

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Ultrasound Doppler: PWUltrasound Doppler: PW

Blood velocity Blood velocity

θθ

Range Cell Range Cell

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Ultrasound PW DopplerUltrasound PW Doppler

Time signals from scatterer moving through range gate Time signals from scatterer moving through range gate 2 MHz tone burst - 1.5 kHz Doppler shift2 MHz tone burst - 1.5 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

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Ultrasound PW DopplerUltrasound PW Doppler

Amplitude of “in phase” Doppler signal at each sampleAmplitude of “in phase” Doppler signal at each sample2 MHz tone burst - 1.5 kHz Doppler shift2 MHz tone burst - 1.5 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

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Ultrasound PW DopplerUltrasound PW Doppler

Doppler signal sampled at TDoppler signal sampled at TPRFPRF

2 MHz tone burst - 1.5 kHz Doppler shift2 MHz tone burst - 1.5 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

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Ultrasound PW DopplerUltrasound PW Doppler

Frequency of Doppler spectrumFrequency of Doppler spectrum2 MHz tone burst - 1.5 kHz Doppler shift2 MHz tone burst - 1.5 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

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Ultrasound PW DopplerUltrasound PW Doppler

Doppler signal - UndersampledDoppler signal - Undersampled2 MHz tone burst - 6 kHz Doppler shift2 MHz tone burst - 6 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

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Ultrasound PW DopplerUltrasound PW Doppler

Doppler spectrumDoppler spectrum2 MHz tone burst - 6 kHz Doppler shift2 MHz tone burst - 6 kHz Doppler shift

ffPRFPRF = 10 kHz = 10 kHz

Oelze - ECE 571 Lecture 4Oelze - ECE 571 Lecture 4

Ultrasound PW DopplerUltrasound PW Doppler

1.5 kHz Doppler shift 1.5 kHz Doppler shift -1.5 kHz Doppler shift -1.5 kHz Doppler shift

DDII (t) (t)

DDQQ (t) (t)

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Doppler Velocity and CFI (Duplex)Doppler Velocity and CFI (Duplex)

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Doppler Velocity and CFI (Duplex)Doppler Velocity and CFI (Duplex)

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CFICFI

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CFICFI

Mitral valve regurgitation (jet)Mitral valve regurgitation (jet)

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Power DopplerPower Doppler

Power Doppler – thyroid nodulePower Doppler – thyroid nodule

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Power DopplerPower Doppler

Power Doppler – 3D renderingPower Doppler – 3D rendering