Sundaramurthy Aravind, Kote Vivek Bhaskar, Pearson Noah, Boiczyk Gregory M, McNeil Elizabeth M, Nelson Allison J, Subramaniam Dhananjay Radhakrishnan, Rubio Jose E, Monson Kenneth, Hardy Warren N, VandeVord Pamela J, Unnikrishnan Ginu, Reifman Jaques
Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, Fort Detrick, MD, United States.
The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States.
Front Bioeng Biotechnol. 2021 Dec 17;9:757755. doi: 10.3389/fbioe.2021.757755. eCollection 2021.
Despite years of research, it is still unknown whether the interaction of explosion-induced blast waves with the head causes injury to the human brain. One way to fill this gap is to use animal models to establish "scaling laws" that project observed brain injuries in animals to humans. This requires laboratory experiments and high-fidelity mathematical models of the animal head to establish correlates between experimentally observed blast-induced brain injuries and model-predicted biomechanical responses. To this end, we performed laboratory experiments on Göttingen minipigs to develop and validate a three-dimensional (3-D) high-fidelity finite-element (FE) model of the minipig head. First, we performed laboratory experiments on Göttingen minipigs to obtain the geometry of the cerebral vasculature network and to characterize brain-tissue and vasculature material properties in response to high strain rates typical of blast exposures. Next, we used the detailed cerebral vasculature information and species-specific brain tissue and vasculature material properties to develop the 3-D high-fidelity FE model of the minipig head. Then, to validate the model predictions, we performed laboratory shock-tube experiments, where we exposed Göttingen minipigs to a blast overpressure of 210 kPa in a laboratory shock tube and compared brain pressures at two locations. We observed a good agreement between the model-predicted pressures and the experimental measurements, with differences in maximum pressure of less than 6%. Finally, to evaluate the influence of the cerebral vascular network on the biomechanical predictions, we performed simulations where we compared results of FE models with and without the vasculature. As expected, incorporation of the vasculature decreased brain strain but did not affect the predictions of brain pressure. However, we observed that inclusion of the cerebral vasculature in the model changed the strain distribution by as much as 100% in regions near the interface between the vasculature and the brain tissue, suggesting that the vasculature does not merely decrease the strain but causes drastic redistributions. This work will help establish correlates between observed brain injuries and predicted biomechanical responses in minipigs and facilitate the creation of scaling laws to infer potential injuries in the human brain due to exposure to blast waves.
尽管经过多年研究，爆炸产生的冲击波与头部的相互作用是否会导致人类大脑损伤仍是未知。填补这一空白的一种方法是使用动物模型来建立“比例定律”，将在动物身上观察到的脑损伤推算到人类身上。这需要进行实验室实验以及建立动物头部的高保真数学模型，以确定实验观察到的爆炸致脑损伤与模型预测的生物力学响应之间的关联。为此，我们对哥廷根小型猪进行了实验室实验，以开发和验证小型猪头的三维（3-D）高保真有限元（FE）模型。首先，我们对哥廷根小型猪进行实验室实验，以获取脑血管网络的几何结构，并表征脑组织和血管在爆炸暴露典型的高应变率下的材料特性。接下来，我们利用详细的脑血管信息以及特定物种的脑组织和血管材料特性，开发了小型猪头的3-D高保真FE模型。然后，为了验证模型预测结果，我们进行了实验室激波管实验，在实验中我们将哥廷根小型猪置于实验室激波管中，使其暴露于210 kPa的爆炸超压下，并比较两个位置的脑压。我们观察到模型预测压力与实验测量结果之间具有良好的一致性，最大压力差异小于6%。最后，为了评估脑血管网络对生物力学预测的影响，我们进行了模拟，比较了有血管和无血管的FE模型的结果。正如预期的那样，纳入血管会降低脑应变，但不影响脑压预测。然而，我们观察到在模型中纳入脑血管会使血管与脑组织界面附近区域的应变分布变化高达100%，这表明血管不仅会降低应变，还会导致应变的剧烈重新分布。这项工作将有助于确定小型猪中观察到的脑损伤与预测的生物力学响应之间的关联，并有助于创建比例定律，以推断因暴露于冲击波而可能在人类大脑中造成的损伤。
