| Summary: | Background: The laminar flow movement in straight arteries is affected by anatomical factors such as bifurcation, lumen diameter changes or plaques. As a consequence of the local deceleration, the detachment of the boundary layer from the wall develops a disturbed flow, which impacts hemodynamics. It results in a non-uniform distribution of wall shear stress (WSS), which is responsible for atherosclerosis [1]. This phenomenon usually occurs in the carotid bifurcation (CB). Computational methods, MRI and conventional Doppler techniques have been used to establish the correlations between flow disturbance and plaque formation. We propose the use of a new method, called high-frame rate Vector Flow imaging (VFI), which dynamically visualises blood flow velocities in all directions, in the evaluation of the flow characteristics in the CB [2,3,4,5].
Methods: CB geometries and flow patterns in 30 healthy subjects of different age were evaluated using a commercial system equipped with high-frame rate VFI based on a frame rate of 600 Hz. The flow is represented by many coloured vectors, displayed as arrows, showing the different velocity, magnitude and direction at each site.
Results: The correlation between flow disturbances and carotid sinus diameter was confirmed: the more relevant the diameter, the more disturbed the flow. Different CB geometries, affecting the flow behaviours and generating complex flow, such as recirculation, counter eddy, vortex and helical trajectory, were identified (Fig 1).
Conclusions: High-frame rate VFI shows in detail the spatiotemporal characteristics of the flow and demonstrates the strong effect of vessel geometries on the flow patterns.
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