Pulsed and color Doppler analysis of normal carotid bifurcation flow dynamics using an in-vitro model.

An anatomically accurate model of the human carotid bifurcation was studied by using color Doppler flow mapping and pulsed Doppler signal analysis. In concordance with dye injection studies, a zone of flow separation was clearly demonstrated at the origin of the internal carotid artery opposite the flow divider. This zone of flow reversal was detected when the ratio of external to common carotid flow rates was greater than 0.27 and became progressively larger as the ratio increased, finally evolving into a zone of heterogenous flow at a ratio greater than 0.5. The authors conclude that the zone of flow reversal seen in the human carotid artery is a geometric property of the bifurcation and that its size depends on the relative flow between both branches. Doppler color imaging can be used to noninvasively map out its extent.