Monday  |  Conference Center A  |  10:40 AM–11:00 AM

#13820, Imaging Based Failure Biomechanics of Diseased Intracranial Aneurysm Wall Tissue

Spontaneous rupture of intracranial aneurysms (IA), the pathological enlargement of the cerebral arterial wall, is a devastating disease with high mortality and disability rates [1]. Mechanisms of IA rupture are poorly understood, thereby making it difficult for clinicians to confidently choose aggressive and somewhat risky treatment protocols over careful observation [2-3]. As IA rupture ultimately involves the loss of structural integrity of the wall tissue, failure biomechanics is expected to play an important role in mechanistic understanding of this disease. In terms of typical material characterization tests such as uniaxial and biaxial testing, aneurysm wall tissue has proven to be very complex and heterogeneous [4]. We developed a protocol for constructing imaging data-derived high fidelity structural models of the diseased intracranial arterial wall tissue to understand how the interaction among disparate tissue components can influence aneurysmal failure. Briefly, wall structural heterogeneity is elicited using micro-scale imaging modalities such as micro-CT and scanning multiphoton microscopy. Tissue calcification and lipid pools are segmented from CT scans, while collagen and elastin fiber architecture is quantified from scanning multiphoton microscopy images. Scanning multiphoton imaging captures a greater field of view of collagen and elastin fiber architecture than previous imaging techniques. Additionally, the use of the CTFire [5] algorithm allows a greater number of fibers to be traced, removal of user bias in manual tracing, providing a better characterization of fiber architecture. Finally, a protocol to include a more realistic embedded fiber structure, namely three-dimensional waviness, has been established. In combination with these new methods, a custom embedded fiber-based finite element algorithm that incorporates individual collagen fibers within the IA tissue [6] will be utilized to elucidate the sub-tissue scale failure phenomena and the role of these fiber-level mechanisms on the emergent wall failure pathways.

[1] Kelly, P et al., Stroke, 32(2):530-534, 2001
[2] Broderick, J. P. et al., Stroke 40(6):1952-7, 2009
[3] Juvela, S et al., Stroke, 44(9): 2413-21, 2013
[4] Robertson, A. M. et al., Ann Biomed Eng, 43: 1502-1515, 2015
[5] Bredfeldt, J. S. et al., J Biomed Optics, 19(1): 016007, 2014
[6] Fortunato, R. N. et al., Exp Mech, 61: 5-18, 2021

Ronald Fortunato   University of Pittsburgh
Mehdi Ramezanpour   University of Pittsburgh
Yasutaka Tobe   University of Pittsburgh
Anne Robertson   University of Pittsburgh
Spandan Maiti   University of Pittsburgh