ultrasound doppler modesweb.stanford.edu/class/rad225/subdir/class12.pdf · doppler modes spectral...

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Rad225/Bioe225 Ultrasound Fall 2019 Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis 2D image of flow field Qualitative visualization Continuous Wave Pulsed Wave Color Flow Power Very high velocities No depth resolution Max velocity limit Sample Gate Control Mean velocity Angle dependent

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Page 1: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

Doppler ModesSpectral Doppler Color Flow Imaging

✤Velocity/freq - time spectrogram✤Quantitative analysis

✤2D image of flow field✤Qualitative visualization

Continuous Wave

Pulsed Wave

Color Flow Power

Very high velocities

No depth resolution

Max velocity limit

Sample Gate Control

Mean velocity

Angle dependent

Page 2: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Doppler

B-mode imageSubset of B-mode image is displayed in color modeColor overlay of the velocity

Toward transducer is in upper color, away in lower color

Page 3: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Simple Description

Interrogate each line 8-10 times.Compare.“Stationary stuff subtracts out.”

• Stationary stuff stays the same• Moving stuff changes

Page 4: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Phase Shift Autocorrelation

Interrogate each line 8-10 times. Looking at the change in the phase of the signals from one transmit pulse to the next.The phase autocorrelation is used to form an average Doppler frequency.

Page 5: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Doppler Angle Effects

Low frequency Doppler signals removed by wall filter

Steady flow phantom

Page 6: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Doppler - Beam Angling

Page 7: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Doppler - Beam Angling

Page 8: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Doppler Angle Effects

Steady flow phantom

Aliasing

Page 9: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Doppler - Color Flow

• Uses multiple gates - allows velocity measurements in many locations.

• But only measure a mean in each location - fewer measurements/location.

• Overlay a color on a greyscale image.

Page 10: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Flow of Ureter Jets

Page 11: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Flow of Ureter Jets

Page 12: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Frame Rate Considerations

Interrogate each line 8-10 times.

Page 13: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019What happens when transducer is rotated?

Need to be careful of how to hold the transducer.

Page 14: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Wall Filter

Page 15: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

Doppler ModesSpectral Doppler Color Flow Imaging

✤Velocity/freq - time spectrogram✤Quantitative analysis

✤2D image of flow field✤Qualitative visualization

Continuous Wave

Pulsed Wave

Color Flow Power

Very high velocities

No depth resolution

Max velocity limit

Sample Gate Control

Mean velocity

Angle dependent

Signal amplitude

Angle independent

Page 16: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Power

• Anywhere where there is a measurable velocity, encode the image with color. The color depends on the amplitude(strength) of the Doppler signal.

• More sensitive than color flow, even at low angles.

• Aliasing doesn’t affect display.

Page 17: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

Color Flow

Signal Magnitude

Velocity

Color Flow Color Overlay

Power Color Overlay

Page 18: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

Color Flow

Signal Magnitude

Velocity

Color Flow Color Overlay

displays velocity

Where velocity is over a threshhold,

Page 19: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

Power

Signal Magnitude

Velocity

Color Flow Color Overlay

Power Color Overlay

Where velocity is over a threshhold,displays Doppler signal magnitude

Page 20: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Flow vs Power

Page 21: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Power Doppler• Any measurable velocity is encoded with color. The color depends on the amplitude of the doppler signal. • More sensitive than color flow (not clear why, potentially due to frame averaging).

Page 22: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Flow vs Power

Page 23: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019Color Flow vs Power

Page 24: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

What kind of Doppler image?

Why is the structure indicated by the dashed arrow not colored?

Why is the structure indicated by the green arrow not colored?

Page 25: Ultrasound Doppler Modesweb.stanford.edu/class/rad225/subdir/Class12.pdf · Doppler Modes Spectral Doppler Color Flow Imaging Velocity/freq - time spectrogram Quantitative analysis

Rad225/Bioe225

Ultrasound

Fall 2019

fUS imaging relies on ultrafast imaging scanners that are able to acquire images at thousands of frames per second. Instead of the line per line acquisition of conventional ultrasound devices, ultrafast ultrasound takes advantage of successive tilted plane wave transmissions that are afterward coherently compounded to form images at high frame rates.