Beta 1


Title Ultrasound Flow Estimation
Author Henze, Lasse
Supervisor Jensen, Jørgen Arendt (Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Bachelor thesis
Year 2008
Abstract A method for measuring the transverse velocity component is proposed. The method measures the transit time of the blood scatterers between two, receive beamformed lines. The transit time is estimated by correlating the beamformed lines taken from different emissions. The largest correlating will occur when the temporal span between the lines being correlated corresponds to the transit time of the blood scatterers. Compensation for the axial velocity is applied. The method has been investigated using Field simulations for a parameter study. Using 15 emissions to create an estimate, a standard deviation of 1.64% and a bias of 1.13% are obtained for a beam to flow angle of 90 degrees. Using the same setup a standard deviation of 2.21% and a bias of 1.07% are obtained for a beam to flow angle of 75 degrees. Using 20 emissions, a standard deviation of 3.4% and a bias of 2.06% are obtained for a beam to flow angle of 45 degrees. The simulation results have been confirmed by phantom measurements. Using 20 emissions to create an estimate, a standard deviation of 3.77% and a bias of 1.68% are obtained for a beam to flow angle of 90 degrees. For a beam to flow angle of 75 degrees a standard deviation of 3.45% and a bias of -.12% are obtained and for a beam to flow angle of 60 degrees a standard deviation of 4.68% and a bias of -1.45% are obtained. In-vivo measurements of the common carotid artery, the carotid bifurcation and vena jugularis have been conducted. Using the measured velocities, the spatial pressure gradients of the carotid bifurcation have been estimated. The estimator needs 53.75 MFLOPS for a real implementation with a pulse repetition frequency of 4000 Hz, 50 estimates pr line and 15 emission pr estimate.
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Admin Creation date: 2009-06-25    Update date: 2009-06-25    Source: dtu    ID: 245563    Original MXD