Multimodality Imaging-Based Characterization of Regional Material Properties in a Murine Model of Aortic Dissection

Abstract

chronic infusion of angiotensin-ii in atheroprone (ApoE −/−) mice provides a reproducible model of dissection in the suprarenal abdominal aorta, often with a false lumen and intramural thrombus that thickens the wall. Such lesions exhibit complex morphologies, with different regions characterized by localized changes in wall composition, microstructure, and properties. We sought to quantify the multiaxial mechanical properties of murine dissecting aneurysm samples by combining in vitro extension-distension data with full-field multimodality measurements of wall strain and thickness to inform an inverse material characterization using the virtual fields method. A key advance is the use of a digital volume correlation approach that allows for characterization of properties not only along and around the lesion, but also across its wall. Specifically, deformations are measured at the adventitial surface by tracking motions of a speckle pattern using a custom panoramic digital image correlation technique while deformations throughout the wall and thrombus are inferred from optical coherence tomography. These measurements are registered and combined in 3D to reconstruct the reference geometry and compute the 3D finite strain fields in response to pressurization. Results reveal dramatic regional variations in material stiffness and strain energy, which reflect local changes in constituent area fractions obtained from histology but emphasize the complexity of lesion morphology and damage within the dissected wall. This is the first point-wise biomechanical characterization of such complex, heterogeneous arterial segments. Because matrix remodeling is critical to the formation and growth of these lesions, we submit that quantification of regional material properties will increase the understanding of pathological mechanical mechanisms underlying aortic dissection.

Sensitivity analysis of non‐local damage in soft biological tissues

“…Meanwhile, some important aspects, such as the influence of the residual stresses, the smooth muscle activation, the lipid pool should also be considered. Besides, some uncertainty analyses about the geometry and the material parameters of the plaque, which is important in predicting the rupture risk of the artery, should be conducted, and the spatial uncertainty should also be considered as arteries are usually heterogeneous materials 50,51 . Moreover, there is still a pressing need to develop further experiments to identify the distribution of shear moduli, the internal length scales and other unknown material parameters.…”

Ultrasound Monitoring of Descending Aortic Aneurysms and Dissections in Mice

“…Word count: 798 words Reference: 5 citations Several modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound, are available to visualize mouse aortas. [1][2][3] CT and MRI enable us to obtain reliable images of the aorta and its branches. However, CT requires vascular contrast and MRI is procedurally complex.…”

General finite-element framework of the Virtual Fields Method in Nonlinear Elasticity

“…In the more and more common situations when full-field measurements are available [20, 21, 22, 7, 23, 24, 25], an alternative to FEMU is possible: the Virtual Fields Method (VFM), which has been shown to be more direct and robust with respect to unknown boundary conditions in these situations [26].…”

“…These virtual fields were valid for the very specific problem of inflation of thin-wall cylinder-like structures. The extension to thick-wall was solved in further papers [30, 25] by weighting locally the virtual fields with a Gaussian function, which was successfully centered at the middle of square patches in order to identify the distribution of material properties across the whole cylinder.…”

“…the expression of virtual fields used in most of previous studies [27, 30, 31] was well adapted to the 2D geometries such as membranes or shells but there is a range of samples or materials in which boundary conditions or geometries or both cannot be straightforwardly designed or chosen to be 2D. With the acquisition of fully volumetric deformation fields which is expanding for soft tissues [23, 24, 25, 32, 33, 34, 35], there is a need for a method that can provide virtual fields for any 3D geometry and virtual field.…”