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2-D angle independent blood velocity estimates are typically achieved by combining the Doppler frequency measurements obtained from two US beams with known interbeam angle. A recently introduced dual-beam vector Doppler method employs one (reference) beam to identify the flow direction, and the other to measure the velocity magnitude. The flow direction is found when the reference beam is set at 90deg...
The possibility of accurately measuring the velocity of blood flowing in human vessels represents a significant opportunity for hemodynamic research and diagnosis. The ultrasound (US) investigation represents a non invasive, diffuse and low cost method capable of evaluating the blood velocity by exploiting the Doppler effect. Unfortunately, the accuracy attainable with standard US equipment is heavily...
The lack of knowledge of the beam-flow angle represents one of the major sources of uncertainty in Doppler measurements. Not only are some new, appealing applications of the Doppler technique prevented, but some basic clinical procedures are made more difficult than desirable. This paper reports on the Doppler angle ambiguity problem and on the classic solutions so far proposed in order to overcome...
Doppler ultrasound (US) techniques are widely used in diagnostics to evaluate the maternal and fetal hemodynamics. Most of these studies involve the assessment of the blood flow in the fetal aorta, umbilical artery, and the uteroplacental circulation. The analysis is typically limited to the echoes originated from a sample volume (SV) covering the whole section of the vessel. Both the shape of the...
Traditional Doppler methods measure only the axial component of the velocity vector. The lack of information on the beam-flow angle creates an ambiguity that can lead to large errors in velocity magnitude estimates. Different triangulation techniques so far have been proposed, which basically perform multiple measurements of the Doppler frequency shift originating from the same region. In this work,...
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