Impact of plaque haemorrhage and its age on structural stresses in atherosclerotic plaques of patients with carotid artery disease: an MR imaging-based finite element simulation study

Abstract

Plaque haemorrhage (PH) in atherosclerotic plaques is associated with recurrent thromboembolic ischaemic events. The healing process predominantly involves the repair of the plaque rupture site and the replacement of fresh PH with chronic PH, which is either reabsorbed or replaced by fibrous tissue. The extent to which the presence of PH, and its type i.e. fresh or chronic, affects plaque stability remains unexplored. Finite element analysis (FEA)-based biomechanical stress simulations can provide quantification of the percentage contribution of PH and its types to the biomechanical stresses of plaques, thereby providing information about its role in plaque stability. Fifty-two patients with atherosclerotic carotid disease underwent high resolution magnetic resonance (MR) imaging of their carotid arteries in a 1.5 Tesla MR system. Twenty-three patients had MR-identifiable PH and were selected. Only those images of these patients were used for simulations, which had evidence of PH. Manual segmentation of plaque components, such as lipid pool, fibrous tissue, calcium and PH, was done using carotid MR images. Plaque components and vessel wall were modelled as isotropic, incompressible hyperelastic materials with non-linear properties undergoing deformation under patient-specific blood pressure loading. Two dimensional structure-only FEA was used for quantification of maximum critical stress (M-CStress) of plaques. The median M-CStress of symptomatic patients with fresh PH was 159 kPa (IQR: 114-253). Because PH usually occurs within the lipid pool, when the simulation was repeated with lipid pool replacing fresh PH to simulate the pre-rupture plaque state, M-CStress was reduced by 26% [118 kPa (IQR: 79-189) (P=0.001)]. When fresh PH was replaced with chronic PH it resulted in a 30% reduction in the M-CStress [118 kP (IQR: 79-189), (P=0.001)]. PH affects stresses within atheroma to various degrees depending on its type, thereby influencing plaque stability to a different extent, with fresh PH significantly increasing the biomechanical stresses. Plaque component-dependent stress analysis has the potential of identifying the critical nature of various plaque components.

Non-contrast 3D black blood MRI for abdominal aortic aneurysm surveillance: comparison with CT angiography

“…Results from ex vivo material testing of AAA specimens showed that material properties of ILTs differ depending on their composition [31, 32]. A previous study on carotid atherosclerotic plaque showed the age of intraplaque haemorrhage can influence the structural stress within a plaque by 30 % [33]. These findings strongly suggest that the use of spatially resolved ILT material properties in computational mechanics simulations may improve the accuracy of AAA wall stress estimates.…”

Non-uniform shrinkage for obtaining computational start shape for in-vivo MRI-based plaque vulnerability assessment

“…The material constants describing different atherosclerotic components are from earlier studies (Sadat et al, 2010b). The pulsatile blood pressure of each patient was used as the loading condition for dynamic simulations.…”

Quantifying Effect of Intraplaque Hemorrhage on Critical Plaque Wall Stress in Human Atherosclerotic Plaques Using Three-Dimensional Fluid-Structure Interaction Models

“…Aglyamov et al applied model-based elasticity reconstruction method to obtain the Young's modulus of the blood clot during formation and aging of thrombus [39]. Based on their data, least squares fitting method were empioyed to obtain the material parameters for hemorrhage: chronic hemorrhage, Ci=9kPa, Di =9kPa, D2 = 0.25; fresh hemorrhage, c, = 1 kPa, Dj = 1 kPa, D2 = 0.25 [29]. The stress-stretch plots for the material of different components derived from the modified Mooney-Rivlin model were presented in Fig.…”

“…However, the discussion about the impact of the IPH on critical mechanical conditions such as plaque wall stress and flow shear stress remains very limited. Sadat et al reported that the aging of hemorrhage would help in plaque stabilization using 2D MRI-based computational modeling [29]. Huang et al determined the potential relationship between PWS and FSS with the location of IPH using FSI models for five human carotid plaques [30].…”