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Session: Poster session 2 (Odd numbers)
Session starts: Friday 27 January, 10:00
Presentation starts: 10:00

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Janna Ruisch ()
Suzanne Holewijn ()
Michel Reijnen ()
Chris de Korte ()
Anne Saris ()

Abstract:
Rupture of a carotid plaque may lead to stroke. Patient selection for surgical plaque removal, carotid endarterectomy, is far from perfect; the number-needed-to-treat in patients with severe stenosis is six to prevent one stroke within 5-years. Ultrasound is, together with CT-scanning, the technique of choice for treatment planning, in which simple geometrical and blood velocity measures are used. However, conventional ultrasound-based velocity measurements assess the along-the-beam velocity component, resulting in large variability. Together with the low frame rates, this restricts measurement of complex or high blood velocity. Especially these complex flow patterns, and the resulting wall shear stresses (WSS) acting on the vessel wall, are crucial for plaque initiation, growth and rupture. The advent of ultrafast, i.e. high-frame-rate, ultrasound makes continuous tracking of flow in all directions feasible. High-frame-rate blood flow imaging (BFI) in the carotid artery is possible by using cross-correlation-based speckle tracking. In this project, we aim to assess if and which blood flow-related parameters, such as vorticity, vector complexity and WSS, are associated with plaque growth and vulnerability using non-invasive, ultrasound-based BFI. In two ongoing clinical studies, the relation between flow patterns and plaque growth and vulnerability will be explored. BFI is performed in asymptomatic patients (N=11/85) during 2-year follow-up to evaluate the association between flow patterns and plaque growth. Furthermore, BFI is acquired in patients (N=5/70) scheduled for carotid endarterectomy. Histology staining of the excised plaque will differentiate vulnerable from stable plaques. Vector complexity and vorticity were derived from velocity fields at pre-, max- and post-stenotic regions. Vector complexity (-) defines the spread of velocity vector directions in a region of interest (ROI). Vorticity (rad/s) is the local rotation of blood within an ROI. Preliminary results show the ability to discriminate different regions in stenosed carotid arteries based on these blood flow-related parameters: increased vector complexity was observed at post-stenotic regions compared to pre- and max-stenosis, especially during the systolic phase. By quantifying different blood-flow related parameters from ultrasound-based BFI, we aim to demonstrate the potential of this novel technique to predict plaque growth and vulnerability. In future, this might enable more sophisticated, personalized treatment decision-making.