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RESEARCH PAPERS

A Three-Dimensional Computational Simulation of Some Sources of Measurement Artifact in Microvascular Pulsed Ultrasound Doppler Velocimetry

[+] Author and Article Information
T. D. Brown, L. D. Bell, D. R. Pedersen, W. F. Blair

Departments of Orthopaedic Surgery and Biomedical Engineering, The University of Iowa, Iowa City, Iowa 52242

J Biomech Eng 107(3), 274-280 (Aug 01, 1985) (7 pages) doi:10.1115/1.3138553 History: Received September 22, 1984; Revised May 16, 1985; Online June 15, 2009

Abstract

Recent applications of 20 MHz pulsed ultrasound Doppler velocimetry (PUDVM) in microsurgical research have necessarily employed piezoelectric crystals whose diameter is not negligible compared to the lumen size (1–2 mm) of many vessels of interest. A three-dimensional numerical model was developed to explore relationships between actual and detected flow field parameters, for (steady) Poiseuille flow, when appreciable velocity gradients exist within the PUDVM sample volume. Validation studies showed that highly accurate velocity profiles could be obtained in the limiting case of a very small sample volume (0.1 mm radius), but that for currently employed crystals ( ≈ 0.5 mm radius) there was appreciable underestimation of the centersteam velocity, and appreciable overestimation of the flow stream diameter. Errors in perceived velocity and flow rate were found to be relatively insensitive to perturbations in the sample volume thickness, in the size of the sampling range increment, or in the angle of insonation beam divergence. By contrast, these apparent flow parameters were found to be very sensitive to perturbations of sample volume diameter or of the Dopper angle. Small variations in the degree of partial sample volume overlap of the flowstream periphery were shown to be capable of causing large fluctuations in apparent flow stream diameter.

Copyright © 1985 by ASME
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