Coded ultrasound for blood flow estimation using subband processing

Fredrik Gran, Jesper Udesen, Michael bachmann Nielsen, Jørgen Arendt Jensen

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Abstract

This paper further investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded signals are used to increase SNR, followed by sub-band processing. The received broadband signal, is filtered using a set of narrow-band filters. Estimating the velocity in each of the bands and averaging the results yields better performance compared to what would be possible when transmitting a narrow-band pulse directly. Also, the spatial resolution of the narrow-band pulse would be too poor for brightness-mode (B-mode) imaging and additional transmissions would be required to update the B-mode image. In the described approach, there is no need for additional transmissions, because the excitation signal is broadband and has good spatial resolution after pulse compression. Two different codin-schemes are used in this paper, Barker codes and Golay codes. The performance of the codes for velocity estimation is compared to a conventional approach transmitting a narrow-band pulse. The study was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60 degrees. The flow in the rig was laminar and had a parabolic flow-profile with a peak velocity of 0.09 m/s. The mean relative standard deviation of the reference method using an eight cycle excitation pulse at 7 MHz was 0.544% compared to the peak velocity in the rig. Two Barker codes were tested with a length of 5 and 13 bits, respectively. The corresponding mean relative standard deviations were 0.367% and 0.310%, respectively. For the Golay coded experiment, two 8 bit codes were used, and the mean relative standard deviation was 0.335%.
Original languageEnglish
Title of host publicationMedical Imaging 2007 : Ultrasonic Imaging and Signal Processing
Number of pages10
Publication date2007
PagesArticle Number: 651309
ISBN (Print)978-0-8194-6631-0
DOIs
Publication statusPublished - 2007
EventSPIE Medical Imaging 2007: Image Processing - San Diego, United States
Duration: 17 Feb 200722 Feb 2007
Conference number: 6512

Conference

ConferenceSPIE Medical Imaging 2007
Number6512
CountryUnited States
CitySan Diego
Period17/02/200722/02/2007
SeriesProceedings of S P I E - International Society for Optical Engineering
Volume6513
ISSN0277-786X

Keywords

  • Temporal encoding
  • Medical ultrasound
  • Blood velocity estimation
  • Sub-band processing

Cite this

Gran, F., Udesen, J., Nielsen, M. B., & Jensen, J. A. (2007). Coded ultrasound for blood flow estimation using subband processing. In Medical Imaging 2007: Ultrasonic Imaging and Signal Processing (pp. Article Number: 651309). Proceedings of S P I E - International Society for Optical Engineering, Vol.. 6513 https://doi.org/10.1117/12.703345