Fig 1.
Example of carotid plaque bifurcation.
From the histology cross-section (A) and the high-resolution MRI 9.4 T with ST = 0.25 mm (B).
Fig 2.
Illustration of the 3D PS model of the atherosclerotic carotid plaque (sample 1) obtained from endarterectomy.
Carotid wall (red) shares the surface with FT.
Fig 3.
Stress-stretch equi-biaxial responses of the chosen constitutive models.
The dotted lines show the isotropic fit of the circumferential (solid) and axial (dash dotted) anisotropic responses. The soft (dashed) and the hard (solid) isotropic responses for the FT and LC are also presented for comparison.
Table 1.
Material parameters.
Fig 4.
Computational model with principal material directions.
(A) The discretized model of the vessel wall of sample 1 with hexahedral elements; the central line (white dashed) serves for definition of the axial base ez. (B) Detailed illustration of the coordinate system of an individual element. (C) Detail of element-specific material directions within the vessel wall model; the blue, green and red arrows indicate the circumferential, axial and radial directions, respectively.
Table 2.
Selected factors for DoE with their chosen upper and lower limits.
Fig 5.
Cross-sections representing the model configurations.
Different WT of 0.5 mm (A), 0.25 mm (B) and 0 mm (C). The adventitia (dark blue) is always represented with 2 elements, as well as the media (light green). FT (light blue) increases its volume with decreasing WT. LC representation (pink) is immutable in the same axial position and with the same ST. Details of the wall are presented in the white lumen area.
Table 3.
Analysis of variance for the PPS and PCS.
Fig 6.
Contour maps of two sample 1 models.
Both LC and FT being soft, differing in WT only: WT = 0 mm (A), (C) and WT = 0.5 mm (B), (D). Displacements in (A) and (B) show their 64% overestimation in model (A) with media and adventitia properties replaced by those of the FT. The maps of first principal stresses (C) and (D) show their distribution in the chosen locations (dashed lines) with the arrows indicating maximal PPS and PCS in the respective sections (white dashed lines). In the model with media and adventitia replaced by the FT, the maximal stresses are almost six times higher. Note that (D) is shown without the media and adventitia layers due to very different levels of stresses between the plaque and these layers.
Fig 7.
Cube plots of PPS values [kPa].
Patient 1 (A-B) and patient 2 (C-D). Colours represent a specific factor; red—WT, green—ST, blue—LC stiffness. Cubes A and C represent low stiffness FT while B and D high stiffness FT.
Fig 8.
Cube plots of PPS values [kPa].
Patient 1 (A-B) and patient 2 (C-D). Colours represent a specific factor; red—WT, green—ST, LC stiffness—blue. Cubes A and C represent low stiffness FT while B and D high stiffness FT.