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Speckle in the Doppler signal - correlation of CW-Doppler signals from blood for varying transmit frequency

Publiceringsår: 2002
Språk: Engelska
Sidor: 1499-1502
Publikation/Tidskrift/Serie: 2002 IEEE Ultrasonics Symposium. Proceedings (Cat. No.02CH37388)
Dokumenttyp: Konferensbidrag
Förlag: IEEE

Sammanfattning

Speckle is an unwanted noise in ultrasound images, and appears as returning echoes are coherently summed over the transducer surface. In Doppler applications, the total power of the received spectrum varies in a manner similar to speckle. This paper investigates the correlation of continuous-wave (CW) Doppler signals obtained from simultaneously transmitted carrier frequencies, when a slowly flowing blood stream is insonated. The covariance function of received Doppler power versus transmitted frequency is shown to agree well to a theoretical modelled function, as well as experiments made on static, independent scatterers, even though the present measurements have a larger variability. The speckle to noise ratio of the Doppler signal amplitude was found to be 1.87 (S.E. 0.04), compared to the theoretical number 1.91 valid for pulse-echo imaging. It was also found that average of spectral estimates from independent channels reduce the variability of such estimates

Disputation

Nyckelord

  • Technology and Engineering
  • static independent scatterers
  • received Doppler power
  • covariance function
  • slowly flowing blood stream
  • simultaneously transmitted carrier frequencies
  • continuous-wave Doppler signal correlation
  • received spectrum total power
  • transducer surface
  • returning echoes
  • ultrasound images
  • unwanted noise
  • varying transmit frequency
  • blood
  • Doppler signal speckle
  • CW-Doppler signals
  • speckle to noise ratio
  • variability
  • Doppler signal amplitude
  • pulse-echo imaging
  • spectral estimates
  • independent channels
  • blood perfsion measurements

Övrigt

Proceedings of 2002 IEEE International Ultrasonics Symposium
8-11 Oct. 2002
Munich, Germany
Published
Yes
  • ISBN: 0-7803-7582-3

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