Contrast medium assisted fluid flow measurements

In this paper the development and evaluation of two new approaches for ultrasound time-domain fluid flow measurements by tracking echoes scattered by a contrast agent following injection of a bolus of the contrast agent are described. Their feasibility was investigated by measuring velocity or velocity profile of blood flowing in a mock circulatory loop in vitro. Measurements were made with a one transducer intravessel approach and a two transducer extravessel approach. A hybrid cluster or vector cross-correlation method was used to track the motion of the scatterers in the two transducer time-domain method. This cluster or vector cross correlation method was developed to reduce the ambiguity resulted from misregistration which is a common problem in target tracking by correlating signal patterns. The experimental results show a good agreement between the measured data and those estimated from timing the volume. Although the discussions given in this paper pertain only to blood flow measurements, there is no reason to indicate that these approaches can not be used for fluid flow measurements in an industrial environment if suitable contrast agents can be developed.<
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