# Application of Time-Frequency Analysis : Diagnostic Doppler Ultrasound DATE ： 2013/12/12 REPORTER ：林宗民.

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Application of Time-Frequency Analysis : Diagnostic Doppler Ultrasound DATE ： 2013/12/12 REPORTER ：林宗民

Outline 1.Basic Concepts 2.Doppler Signal 3.Spectral Doppler 4.Doppler Image(Color Doppler, Power Doppler) 5.Conclusion

Ultrasound  Longitudinal wave  Frequency > 20 KHz  Diagnosis Ultrasound ： 1~13 MHz  Velocity ： 343m/s in air 1540m/s in tissue 6420m/s in aluminum http://i299.photobucket.com/albums/mm288/ wasi142/Biological%20classification/waves.jpg

Doppler Effect  Frequency shift due to relative movement.  Doppler frequency ： f d = f – f 0

Ultrasound Image – B mode  Brightness-mode  Backscattered image  Tomography http://content.answcdn.com/main/content/img/McGrawHill/Enc yclopedia/images/CE757525FG0010.gif

 Doppler Signal, x d (t) = iFT{ f d = f r – f t }  Typically ~kHz in diagnosis Doppler ultrasound. Continuous WavePulse Wave Measuring the time-varying Doppler shift Transmitting several pulses and sampling received signals Doppler Signal

Continuous Wave  Transmitting monochromatic wave. Transmitted signal spectrum

Doppler Signal Continuous Wave  Transmitting monochromatic wave.  Received signals from moving tissue plus static tissue. Received signal spectrum f static f moving

Doppler Signal Continuous Wave  Transmitting monochromatic wave.  Received signals from moving tissue plus static tissue.  Demodulation and filtering. Doppler signal spectrum f static f moving

Doppler Signal Continuous Wave  Transmitting monochromatic wave.  Received signals from moving tissue plus static tissue.  Demodulation and filtering. Doppler signal spectrum f moving

Doppler Signal Pulse Wave  Transmitting several pulses.  Multi-gate sampling.

Doppler Signal Pulse Wave  Transmitting several pulses.  Multi-gate sampling.  Doppler signal

Spectral Doppler (Sonogram)  Continuous wave or Pulse wave  Combining B-mode ultrasound with pulsed wave Doppler  STFT has been commonly used. Unbalanced Sampling with ↑50% overlap. http://en.wikipedia.org/wiki/File:SpectralDopplerA.jpg

Simulation Analysis

STFT Cone distribution Bessel Distribution Choi-Williams Distribution

Simulation Analysis Cone distribution Bessel Distribution Choi-Williams Distribution STFT

Color Doppler  Combining B-mode and Doppler signal.  Pulse Wave  Multi-gate system.  Velocity and direction of blood flow are the desire information.  2 spatial dimension + 1 temporal dimension  amount computation.  Auto-correlation method for calculating average frequency.

Power Doppler  Combining B-mode and Doppler signal.  Pulse Wave  Multi-gate system.  Total power of Doppler signal.  Indicating the flow density information.  Not T-F analysis

Conclusion  Image is 3-D signals. It’s not proper to use T-F analysis.  Spectral Doppler is 1-D signals. T-F analysis has been used to measure the blood flow.  In practice, diagnosis signals are more complex than simulated signals, and more noise. Statistic methods are used.

Reference  “The Difference Between Colour Doppler Velocity Imaging and Power Doppler Imaging,” W. N. McDicken and T. Anderson, Eur J Echocardiography(2002)3,240–244  “Time-Frequency Analysis for Doppler Ultrasound signals,” 陳宗銓, http://djj.ee.ntu.edu.tw/Tutorial_Time- Frequency%20Analysis%20for%20Doppler%20Ultrasound%20Signals.docx. http://djj.ee.ntu.edu.tw/Tutorial_Time- Frequency%20Analysis%20for%20Doppler%20Ultrasound%20Signals.docx  “Physics and instrumentation of Diagnostic Medical Ultrasound,” PETER FISH, 1990.  “Evaluation of fetal arrhythmias from simultaneous pulsed wave Doppler in pulmonary artery and vein,” Julene S Carvalho, Federico Prefumo, Valentina Ciardelli, Shanthi Sairam, Amarnath Bhide, Elliot A Shinebourne, 2007.  “The Physical Principles of Doppler and Spectral Analysis,” Peter N. Burns, PhD, J Clin Ultrasound 15567-590. NovemberlDecember 1987.

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