Wall Mechanical Properties and Hemodynamics of Unruptured Intracranial Aneurysms

Cebral, Juan R.; Duan, Xiaoyu; Chung, Bong Jae; Putman, Christopher M.; Aziz, Khaled; Robertson, Anne M.

doi:10.3174/ajnr.a4358

Cited by 63 publications

(47 citation statements)

References 24 publications

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“…Since the fractional order is related with the loss of smooth muscle cells, this aneurysm-specific model as well as the numerical tools developed here may help to understand the structural integrity of the aneurysm wall, and therefore contribute in studying the subclasses of unruptured aneurysm walls [49,50]. …”

Section: Discussionmentioning

confidence: 99%

Fractional modeling of viscoelasticity in 3D cerebral arteries and aneurysms

Perdikaris

Karniadakis

2016

Journal of Computational Physics

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We develop efficient numerical methods for fractional order PDEs, and employ them to investigate viscoelastic constitutive laws for arterial wall mechanics. Recent simulations using one-dimensional models [1] have indicated that fractional order models may offer a more powerful alternative for modeling the arterial wall response, exhibiting reduced sensitivity to parametric uncertainties compared with the integer-calculus-based models. Here, we study three-dimensional (3D) fractional PDEs that naturally model the continuous relaxation properties of soft tissue, and for the first time employ them to simulate flow structure interactions for patient-specific brain aneurysms. To deal with the high memory requirements and in order to accelerate the numerical evaluation of hereditary integrals, we employ a fast convolution method [2] that reduces the memory cost to O(log(N)) and the computational complexity to O(N log(N)). Furthermore, we combine the fast convolution with high-order backward differentiation to achieve third-order time integration accuracy. We confirm that in 3D viscoelastic simulations, the integer order models strongly depends on the relaxation parameters, while the fractional order models are less sensitive. As an application to long-time simulations in complex geometries, we also apply the method to modeling fluid–structure interaction of a 3D patient-specific compliant cerebral artery with an aneurysm. Taken together, our findings demonstrate that fractional calculus can be employed effectively in modeling complex behavior of materials in realistic 3D time-dependent problems if properly designed efficient algorithms are employed to overcome the extra memory requirements and computational complexity associated with the non-local character of fractional derivatives.

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Section: Discussionmentioning

confidence: 99%

Fractional modeling of viscoelasticity in 3D cerebral arteries and aneurysms

Perdikaris

Karniadakis

2016

Journal of Computational Physics

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“…Ex-vivo MPM is used to image collagen fibers in the aneurysm wall of the intact IA sample 5, 23 . A holder was created from a styrofoam block with a cavity well slightly larger than the aneurysm sample.…”

Section: Methods For Quantification Of Aneurysm Characteristicsmentioning

confidence: 99%

“…Furthermore, two subpopulations have been found in a study of unruptured aneurysms, one with weaker more vulnerable walls and another with stronger walls 23 . Additionally, possible associations between global aneurysm hemodynamic characteristics and wall strength and stiffness have been identified 5 . Intramural stresses are also known to strongly influence wall structure and strength 9 .…”

Section: Introductionmentioning

confidence: 99%

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Regional Mapping of Flow and Wall Characteristics of Intracranial Aneurysms

et al. 2016

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The evolution of intracranial aneurysms (IAs) is thought to be driven by progressive wall degradation in response to abnormal hemodynamics. Previous studies focused on the relationship between global hemodynamics and wall properties. However, hemodynamics, wall structure and mechanical properties of cerebral aneurysms can be non-uniform across the aneurysm wall. Therefore, the aim of this work is to introduce a methodology for mapping local hemodynamics to local wall structure in resected aneurysm specimens. This methodology combines image-based computational fluid dynamics, tissue resection, micro-CT imaging of resected specimens mounted on 3D-printed aneurysm models, alignment to 3D vascular models, multi-photon microscopy of the wall, and regional mapping of hemodynamics and wall properties. This approach employs a new 3D virtual marking tool for surgeons to delineate the location of the resected specimen directly on the 3D model, while in the surgical suite. The case of a middle cerebral artery aneurysm is used to illustrate the application of this methodology to the assessment of the relationship between local wall shear stress and local wall properties including collagen fiber organization and wall geometry. This methodology can similarly be used to study the relationship between local intramural stresses and local wall structure.

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“…The adverse flow conditions described above have been previously shown to be associated with aneurysm wall inflammation which itself is associated with aneurysm rupture 27 , wall weakening and stiffening characteristic of vulnerable walls 28, 29 , and damaged collagen architectures 30 . Additionally, these flow conditions have been associated with aneurysm rupture 31 .…”

Section: Discussionmentioning

confidence: 95%

Hemodynamic Characteristics of Ruptured and Unruptured Multiple Aneurysms at Mirror and Ipsilateral Locations

Doddasomayajula

Chung

Mut

et al. 2017

AJNR Am J Neuroradiol

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Background and Purpose Different hemodynamic patterns have been associated with aneurysm rupture. The objective was to test whether hemodynamic characteristics of the ruptured aneurysm in patients with multiple aneurysms were different from unruptured aneurysms of the same patient. Materials and Methods A total of 24 mirror and 58 ipsilateral multiple aneurysms with one ruptured and the other(s) unruptured were studied. Computational fluid dynamics models were created from 3D angiographies. Case-control studies of mirror and ipsilateral aneurysms were performed using paired Wilcoxon tests. Results In mirror pairs, the ruptured aneurysm had more oscillatory wall shear stress (WSS) (p=0.007) than the unruptured one, and tended to be more elongated (higher aspect ratio), although this trend only achieved marginal significance (p=0.0302 one-sided test). In ipsilateral aneurysms, ruptured aneurysms had larger maximum WSS (p=0.0501), more concentrated (p=0.0007) and oscillatory WSS (p=0.0001), stronger (p=0.0001) and more concentrated inflow jets (p=0.0001), larger maximum velocity (p=0.0003), and more complex flow patterns (p=0.0001) compared to unruptured aneurysms. Additionally, ruptured aneurysms were larger (p=0.0001), more elongated (p=0.0001), had wider necks (p=0.0003), and lower minimum WSS (p=0.0002) than unruptured aneurysms. Conclusions High WSS oscillations and larger aspect ratios are associated with rupture in mirror aneurysms. Adverse flow conditions characterized by high and concentrated inflow jets, high, concentrated and oscillatory WSS, and strong, complex and unstable flow patterns are associated with rupture in ipsilateral multiple aneurysms. In multiple ipsilateral aneurysms, these unfavorable flow conditions are more likely to develop in larger, more elongated, wider necked, and more distal aneurysms.

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Wall Mechanical Properties and Hemodynamics of Unruptured Intracranial Aneurysms

Cited by 63 publications

References 24 publications

Fractional modeling of viscoelasticity in 3D cerebral arteries and aneurysms

Fractional modeling of viscoelasticity in 3D cerebral arteries and aneurysms

Regional Mapping of Flow and Wall Characteristics of Intracranial Aneurysms

Hemodynamic Characteristics of Ruptured and Unruptured Multiple Aneurysms at Mirror and Ipsilateral Locations

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