Estimation of flow velocity vectorial profile by ultrasound color Doppler mapping

Color Doppler mapping by ultrasound (UCDM) imaging systems provides qualitative description of flow velocity. When studying flow behavior, specifically ahead of a bifurcation, quantification is required, so as to allow description of the 3-dimensional vectorial components. The measurement of flow velocity by UCDM, using a commercial imaging system, is convenient yet allows good estimation of the vectorial component only in the line of insonation. This report describes measurements of the flow velocity profile in a phantom of the carotid artery with its branching into the internal and external carotid arteries. The hypothesis was that using an accurate positioning system, the flow velocity profile can be estimated with a sensitivity high enough to measure all the flow components near the bifurcation. It was found that averaging of images was required. After averaging, insonation from two carefully measured orientations allowed calculation of axial and radial components of the flow velocity: the accuracy obtained was with a correlation better than 0.99, and SD of 0.37°. The SD doubled when flow velocity was increased from Re=450 to Re=631. Thus, Quantification of 3D flow velocity measurement is possible, but requires modification of present systems