Improved accuracy in the estimation of blood velocity vectors using matched filtering

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Abstract

The blood velocity can be estimated by finding the shift in position of the blood scatterers between subsequent ultrasonic pulse emissions through cross-correlation of the received RF signals. Usually only the velocity component along the beam direction is found. It was shown in a previous paper that the complete velocity vector can be found, if the received signals are focused along lines parallel to the direction of the blood flow. A fairly broad beam is emitted in the approach, and this gives rise to a widening in the profiles of the estimated velocity. To reduce this effect, a focused ultrasound emission is used in this study to decrease the size of the beam. The transverse beam lines are then constructed by using filters matched to the response of the individual channels. The filters matched to the points on the focusing lines are obtained by considering the field response of the employed array transducer. The effect of the processing is studied through simulations with the Field II program. A 64-elements linear array with a center frequency of 3 MHz, pitch of 0.3 mm, and element height of 5 mm is used in the simulations. A parabolic velocity profile is considered for different angles between the flow and the ultrasound beam (30, 45, 60, and 90 degrees). The parabolic flow has a peak velocity of 0.5 m/s and the pulse repetition frequency is 3.5 kHz. Simulating twenty emissions and calculating the cross-correlation using four pulse-echo lines for each estimate, the parabolic flow profile is found with a standard deviation of 0.014 m/s at 45 degrees (corresponding to an accuracy of 2.8%) and 0.022 m/s (corresponding to an accuracy of 4.4%) at 90 degrees, which is transverse to the ultrasound beam.
Original languageEnglish
Title of host publicationProceedings IEEE Ultrason. Symp.
PublisherIEEE
Publication date2000
Pages1525-1530
ISBN (Print)0-7803-6365-5
DOIs
Publication statusPublished - 2000
Event2000 IEEE Ultrasonics Symposium - San Juan, Puerto Rico
Duration: 22 Oct 200025 Oct 2000
http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=7345

Conference

Conference2000 IEEE Ultrasonics Symposium
CountryPuerto Rico
CitySan Juan
Period22/10/200025/10/2000
Internet address

Bibliographical note

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