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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Joerik de Ruijter (Eindhoven University of Technology)
Frans van de Vosse (Eindhoven University of Technology)
Marc van Sambeek (Catharina Ziekenhuis)
Richard Lopata (Eindhoven University of Technology)

Abstract:
Plaques in carotid arteries are a common cause of stroke. Rupture risk is related to high peak stresses in the shoulders or cap of the plaque. Patient-specific, high-resolution, 3-D biomechanical models are required for a reliable calculation of the magnitude of the peak stresses, which requires an accurate 3-D geometry. In this study, a high-resolution 2-D linear array is used in combination with a magnetic probe tracking device, for 3-D geometry reconstruction of the carotid bifurcation. An automated segmentation and meshing method was developed to create a patient-specific mechanical model for simulation of flow and stress, with minimal user input, and tested in a volunteer study. The method was tested in vivo on 20 healthy volunteers. By making a slow sweep (6 cm) over the patient’s neck, the full geometry of the bifurcated geometry of the carotid artery is captured. In the first frame, seeds were placed in the centers of the internal and external carotid. The Star-Kalman method was used to approximate the center and the size of the vessel(s) for every frame. Images were filtered with a Gaussian high-pass filter before conversion into the 2-D monogenic signals. Multiscale asymmetry features were extracted from these data, enhancing low lateral wall-lumen contrast. These images, in combination with the initial ellipse contours, were used for an active deformable contour model to segment the vessel lumen. Distension of the wall due to the change in blood pressure is removed using a filter approach. Results were compared to manual segmentation performed by experienced observers. Finally, the contours were converted into a 3-D hexahedral mesh for finite element analysis in ANSYS. Simulations were performed to estimate stress in the wall, and flow in the lumen. The segmentation algorithm showed good agreement with an average Similarity Index of 0.90 and Hausdorff distance of 0.8±0.4 mm. For the CCA a diameter of 6.8±1.1 mm was found and for ICA/ECA 5.4±0.7 mm, which is comparable with clinical data. The presented algorithm can be applied to generate fluid structure interaction models automatically based on in vivo measurements. In future, these models will be extended to diseased carotid arteries.