Deconvolution process in measurement of arterial velocity profiles via an ultrasonic pulsed Doppler velocimeter for evaluation of the wall shear rate

Flaud, Patrice; Bensalah, Aziz; Péronneau, P.

doi:10.1016/s0301-5629(96)00200-1

Cited by 18 publications

(9 citation statements)

References 14 publications

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“…The situation is close to a clinical case when considering the Womersley number and the Reynolds number based on the mean flux rate. A complete description of the experimental setup can be found in [14,22]. The fluid US echogenicity was monitored by adding small latex particles.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

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An inverse method for non-invasive viscosity measurements

Fullana

Dispot

Flaud

et al. 2007

Eur. Phys. J. Appl. Phys.

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A procedure is presented which allows to compute in a non-invasive manner, blood viscosity through flow measurements obtained at a fixed vessel cross-section. The data set is made of measurements (artery radius and spatially discrete velocity profiles) performed at given time intervals for which the signal to noise ratio is typical of U.S. Doppler velocimetry in clinical situation. This identification approach is based on the minimization, through a backpropagation algorithm, of a cost function quantifying the distance between numerical data obtained through Navier-Stokes simulations and experimental measurements. Since this cost function implicitly depends on the value of viscosity used in numerical simulations, its minimization determines an effective viscosity which is shown to be robust to measurement errors and sampling time. Such an approach is shown to work in an in vitro experiment, and seems to be suitable for in vivo measurements of viscosity by the atraumatic techniques of Doppler echography.

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Section: Experimental Setup and Resultsmentioning

confidence: 99%

“…γ Ns,k − v Ns−2,k − 4v Ns−1,k 2∆r ψ Ns,k where ϕ jk , χ jk and ψ jk are Lagrange multipliers. When equations (22,23) and (25) are satisfied, L = F so that δL = δF for any values of variables ϕ jk , χ jk and ψ jk .…”

Section: Appendix A: the Algorithm For The Discretized Model And Measmentioning

confidence: 99%

An inverse method for non-invasive viscosity measurements

Fullana

Dispot

Flaud

et al. 2007

Eur. Phys. J. Appl. Phys.

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“…Errors in positioning of the sample volume as well as distortion due to the size of the sample volume may be significant. 12 Such problems may be alleviated through the deconvolution process suggested by Flaud and coworkers. 12 However, this technique requires an iterative selection of the best deconvolution window, which makes it less attractive in practice.…”

Section: Discussionmentioning

confidence: 99%

“…12 Such problems may be alleviated through the deconvolution process suggested by Flaud and coworkers. 12 However, this technique requires an iterative selection of the best deconvolution window, which makes it less attractive in practice. Finally, compromises in velocity scale settings are necessary.…”

Section: Discussionmentioning

confidence: 99%

“…Approaches based on high frequency (20 MHz) pulsed Doppler interrogation and on RF data acquisition of Doppler signals with advanced signal processing hardware and software have been reported. [8][9][10][11][12] However, all of these methods require equipment and processing which are not readily available in a clinical setting. As an alternative, we measured the wall shear rate using a commercially available ultrasound scanner (P700, Philips Ultrasound, Irvine, CA).…”

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Shear rate estimation using a clinical ultrasound scanner.

Forsberg

Morvay

Rawool

et al. 2000

Journal of Ultrasound in Medicine

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Wall shear stress is a factor in the development of atherogenesis, thrombus formation, and embolization, but its existence is very difficult to determine with ultrasonography. Instead, we estimated shear rates using a clinical ultrasound scanner and compared results from vessels with and without stenoses. Velocity profiles were obtained from color M-mode images on a P700 scanner. Maximum shear rates were calculated off-line as the maximum velocity gradients. In vitro, studies were performed on a flow phantom with a vessel containing a 50% stenosis. Shear rates within the stenosis were significantly higher than those obtained outside the stenosis (P < 0.00001) and varied more than the peak velocities. In vivo, the internal carotid artery of 10 volunteers and 13 patients (with stenoses) was studied. The mean shear rate was 414 s(-1) +/- 154.5 s(-1) in normal vessels and 687 s(-1) +/- 263.5 s(-1) in stenotic vessels (P = 0.00017). In conclusion, shear rate estimates can be obtained with a clinical ultrasound scanner from color M-mode images. Shear rates estimated in vessels with stenoses are significantly higher than those obtained in normal vessels in vitro as well as in vivo.

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