Flow velocity distribution near the arterial bifurcation by Doppler ultrasound mapping

A latex phantom of the carotid artery, with its bifurcation, was placed in a highly accurate measurement system. Steady, laminar flow was induced, and its velocity measured by Doppler UltraSound Mapping (DUSM). Orientation and location of the DUSM probe were registered concurrently, so as to allow calculation of the velocity vectorial components. Axial and non-axial components of the flow velocity vectors correlated well (>0.99) with calculated values. The low SD (2.3 cm/sec for axial flow, 0.63 degrees for the angle of the non-axial component), allowed calculating the axial flow velocity distribution at the bifurcation, and its deviation from symmetry. An index of asymmetry changed from `normal´ 115±17 (for 6.0 and 4.0 mm branches) to 79±12 when the 6.0 mm branch was occluded. The changes increased for higher flow velocities