Coded ultrasound for blood flow estimation using subband processing

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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 coding 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°. 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
Publication date2007
Article number651309
ISBN (Print)081946631X, 9780819466310
Publication statusPublished - 2007
EventMedical Imaging 2007: Ultrasonic Imaging and Signal Processing - San Diego, CA, United States
Duration: 18 Feb 200719 Feb 2007


ConferenceMedical Imaging 2007: Ultrasonic Imaging and Signal Processing
LandUnited States
BySan Diego, CA
SeriesProgress in Biomedical Optics and Imaging - Proceedings of SPIE

    Research areas

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

ID: 331492129