A Continuum Human Brain Model with Embedded Vasculature to Investigate In-Vivo Testing
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The perusal of existing literature reveals conflicting material responses of human brain tissue under various testing modalities, prompting the need for a predictive computational model that can unify these disparate findings. A pivotal step in this direction involves integrating the vascular structure into a continuum material model. This integration seeks to account for the coupling of solid and fluid phases within the tissue, potentially justifying variations observed between in vivo and ex vivo experimental responses. The inclusion of blood vessels in the linear viscoelastic tissue is based on the multiscale immersed method [1]. Where the blood pressure is accounted for in the forcing term and a multidimensional coupling is employed using the reduced Lagrange multiplier method. Our model is extended to mimic the magnetic resonance elastography (MRE) test setup. MRE has previously shown the influence of blood flow on in vivo brain viscoelasticity [2] and can provide cerebral mechanical parameters over multiple length scales, ex vivo and in vivo, in the full brain and in different anatomic regions. The computational model and MRE data are compared to underscore the significance of including vasculature in the brain computational model, especially when working with in vivo and non-invasive experimental setups. [1] L. Heltai, A. Caiazzo, and L. Müller. “Multiscale Coupling of One-dimensional Vascular Models and Elastic Tissues”. Annals of Biomedical Engineering 49 (2021), pp. 3243–3254. [2] S. Hetzer, F. Dittmann, K. Bormann, S. Hirsch, A. Lipp, DJ. Wang, J. Braun, I. Sack. “Hypercapnia increases brain viscoelasticity”. Journal of Cerebral Blood Flow and Metabolism 39 (2019), pp. 2445-2455
