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Huang, Q., Lindgren, N., Zhou, Z., Li, X. & Kleiven, S. (2024). A method for generating case-specific vehicle models from a single-view vehicle image for accurate pedestrian injury reconstructions. Accident Analysis and Prevention, 200, Article ID 107555.
Open this publication in new window or tab >>A method for generating case-specific vehicle models from a single-view vehicle image for accurate pedestrian injury reconstructions
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2024 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 200, article id 107555Article in journal (Refereed) Published
Abstract [en]

Developing vehicle finite element (FE) models that match real accident-involved vehicles is challenging. This is related to the intricate variety of geometric features and components. The current study proposes a novel method to efficiently and accurately generate case-specific buck models for car-to-pedestrian simulations. To achieve this, we implemented the vehicle side-view images to detect the horizontal position and roundness of two wheels to rectify distortions and deviations and then extracted the mid-section profiles for comparative calculations against baseline vehicle models to obtain the transformation matrices. Based on the generic buck model which consists of six key components and corresponding matrices, the case-specific buck model was generated semi-automatically based on the transformation metrics. Utilizing this image-based method, a total of 12 vehicle models representing four vehicle categories including family car (FCR), Roadster (RDS), small Sport Utility Vehicle (SUV), and large SUV were generated for car-to-pedestrian collision FE simulations in this study. The pedestrian head trajectories, total contact forces, head injury criterion (HIC), and brain injury criterion (BrIC) were analyzed comparatively. We found that, even within the same vehicle category and initial conditions, the variation in wrap around distance (WAD) spans 84–165 mm, in HIC ranges from 98 to 336, and in BrIC fluctuates between 1.25 and 1.46. These findings highlight the significant influence of vehicle frontal shape and underscore the necessity of using case-specific vehicle models in crash simulations. The proposed method provides a new approach for further vehicle structure optimization aiming at reducing pedestrian head injury and increasing traffic safety.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Car-to-pedestrian collision, Case-specific buck, Finite element simulations, Head injury, Impact bio-mechanics
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-344929 (URN)10.1016/j.aap.2024.107555 (DOI)2-s2.0-85188682260 (Scopus ID)
Note

QC 20240404

Available from: 2024-04-03 Created: 2024-04-03 Last updated: 2024-04-04Bibliographically approved
Yuan, Q., Li, X., Zhou, Z. & Kleiven, S. (2024). A novel framework for video-informed reconstructions of sports accidents: A case study correlating brain injury pattern from multimodal neuroimaging with finite element analysis. Brain Multiphysics, 6, Article ID 100085.
Open this publication in new window or tab >>A novel framework for video-informed reconstructions of sports accidents: A case study correlating brain injury pattern from multimodal neuroimaging with finite element analysis
2024 (English)In: Brain Multiphysics, E-ISSN 2666-5220, Vol. 6, article id 100085Article in journal (Refereed) Published
Abstract [en]

Ski racing is a high-risk sport for traumatic brain injury. A better understanding of the injury mechanism and the development of effective protective equipment remains central to resolving this urgency. Finite element (FE) models are useful tools for studying biomechanical responses of the brain, especially in real-world ski accidents. However, real-world accidents are often captured by handheld monocular cameras; the videos are shaky and lack depth information, making it difficult to estimate reliable impact velocities and posture which are critical for injury prediction. Introducing novel computer vision and deep learning algorithms offers an opportunity to tackle this challenge. This study proposes a novel framework for estimating impact kinematics from handheld, shaky monocular videos of accidents to inform personalized impact simulations. The utility of this framework is demonstrated by reconstructing a ski accident, in which the extracted kinematics are input to a neuroimaging-informed, personalized FE model. The FE-derived responses are compared with imaging-identified brain injury sites of the victim. The results suggest that maximum principal strain may be a useful metric for brain injury. This study demonstrates the potential of video-informed accident reconstructions combined with personalized FE modeling to evaluate individual brain injury. Statement of significance: Reconstructing real-world sports accidents combined with finite element (FE) models presents a unique opportunity to study brain injuries, as it enables simulating complex loading conditions experienced in reality. However, a significant challenge lies in accurately obtaining kinematics from the often shaky, handheld video footage of such accidents. We propose a novel framework that bridges the gap between real-world accidents and video-informed injury predictions. By integrating video analysis, 3D kinematics estimation, and personalized FE simulation, we extract accurate impact kinematics of a ski accident captured from handheld shaky monocular videos to inform personalized impact simulations, predicting the injury pathology identified by multimodal neuroimaging. This study provides important guidance on how best to estimate impact conditions from video-recorded accidents, opening new opportunities to better inform the biomechanical study of head trauma with improved boundary conditions.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Computer vision, Kinematics estimation, Personalized finite element model, Sports accidents, Traumatic brain injury
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-341761 (URN)10.1016/j.brain.2023.100085 (DOI)2-s2.0-85179804551 (Scopus ID)
Note

QC 20240102

Available from: 2024-01-02 Created: 2024-01-02 Last updated: 2024-01-02Bibliographically approved
Zhou, Z., Li, X., Liu, Y., Hardy, W. N. & Kleiven, S. (2023). Brain strain rate response: Addressing computational ambiguity and experimental data for model validation. Brain Multiphysics, 4, Article ID 100073.
Open this publication in new window or tab >>Brain strain rate response: Addressing computational ambiguity and experimental data for model validation
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2023 (English)In: Brain Multiphysics, E-ISSN 2666-5220, Vol. 4, article id 100073Article in journal (Refereed) Published
Abstract [en]

Traumatic brain injury (TBI) is an alarming global public health issue with high morbidity and mortality rates. Although the causal link between external insults and consequent brain injury remains largely elusive, both strain and strain rate are generally recognized as crucial factors for TBI onsets. With respect to the flourishment of strain-based investigation, ambiguity and inconsistency are noted in the scheme for strain rate calculation within the TBI research community. Furthermore, there is no experimental data that can be used to validate the strain rate responses of finite element (FE) models of the human brain. The current work presented a theoretical clarification of two commonly used strain rate computational schemes: the strain rate was either calculated as the time derivative of strain or derived from the rate of deformation tensor. To further substantiate the theoretical disparity, these two schemes were respectively implemented to estimate the strain rate responses from a previous-published cadaveric experiment and an FE head model secondary to a concussive impact. The results clearly showed scheme-dependent responses, both in the experimentally determined principal strain rate and model-derived principal and tract-oriented strain rates. The results highlight that cross-scheme comparison of strain rate responses is inappropriate, and the utilized strain rate computational scheme needs to be reported in future studies. The newly calculated experimental strain rate curves in the supplementary material can be used for strain rate validation of FE head models.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Rate of deformation tensor, Strain rate validation, Time derivative of strain, Traumatic brain injury
National Category
Neurosciences
Identifiers
urn:nbn:se:kth:diva-331558 (URN)10.1016/j.brain.2023.100073 (DOI)2-s2.0-85159719846 (Scopus ID)
Note

QC 20230711

Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-07-11Bibliographically approved
Wang, F., Peng, K., Zou, T., Li, Q., Li, F., Wang, X., . . . Zhou, Z. (2023). Numerical Reconstruction of Cyclist Impact Accidents: Can Helmets Protect the Head-Neck of Cyclists?. Biomimetics, 8(6), Article ID 456.
Open this publication in new window or tab >>Numerical Reconstruction of Cyclist Impact Accidents: Can Helmets Protect the Head-Neck of Cyclists?
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2023 (English)In: Biomimetics, E-ISSN 2313-7673, Vol. 8, no 6, article id 456Article in journal (Refereed) Published
Abstract [en]

Cyclists are vulnerable road users and often suffer head-neck injuries in car–cyclist accidents. Wearing a helmet is currently the most prevalent protection method against such injuries. Today, there is an ongoing debate about the ability of helmets to protect the cyclists’ head-neck from injury. In the current study, we numerically reconstructed five real-world car–cyclist impact accidents, incorporating previously developed finite element models of four cyclist helmets to evaluate their protective performances. We made comparative head-neck injury predictions for unhelmeted and helmeted cyclists. The results show that helmets could clearly lower the risk of severe (AIS 4+) brain injury and skull fracture, as assessed by the predicted head injury criterion (HIC), while a relatively limited decrease in AIS 4+ brain injury risk can be achieved in terms of the analysis of CSDM0.25. Assessment using the maximum principal strain (MPS0.98) and head impact power (HIP) criteria suggests that helmets could lower the risk of diffuse axonal injury and subdural hematoma of the cyclist. The helmet efficacy in neck protection depends on the impact scenario. Therefore, wearing a helmet does not seem to cause a significant neck injury risk level increase to the cyclist. Our work presents important insights into the helmet’s efficacy in protecting the head-neck of cyclists and motivates further optimization of protective equipment.

Place, publisher, year, edition, pages
MDPI AG, 2023
Keywords
cyclist impact accident, head/brain injury, helmet, neck injury, numerical simulation
National Category
Other Medical Engineering Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-339485 (URN)10.3390/biomimetics8060456 (DOI)001094239500001 ()2-s2.0-85175028293 (Scopus ID)
Note

QC 20231113

Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2023-11-29Bibliographically approved
Majdolhosseini, M., Zhou, Z., Kleiven, S. & Villa, A. (2023). Which part of axonal membrane is the most vulnerable: A molecular dynamics/Finite Element study. European Biophysics Journal, 52(SUPPL 1), S39-S39
Open this publication in new window or tab >>Which part of axonal membrane is the most vulnerable: A molecular dynamics/Finite Element study
2023 (English)In: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 52, no SUPPL 1, p. S39-S39Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
SPRINGER, 2023
National Category
Neurology
Identifiers
urn:nbn:se:kth:diva-335858 (URN)001029235400068 ()
Note

QC 20230911

Available from: 2023-09-11 Created: 2023-09-11 Last updated: 2023-09-11Bibliographically approved
Zhou, Z., Wang, T., Jörgens, D. & Li, X. (2022). Fiber orientation downsampling compromises the computation of white matter tract-related deformation. Journal of The Mechanical Behavior of Biomedical Materials, 132, Article ID 105294.
Open this publication in new window or tab >>Fiber orientation downsampling compromises the computation of white matter tract-related deformation
2022 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 132, article id 105294Article in journal (Refereed) Published
Abstract [en]

Incorporating neuroimaging-revealed structural details into finite element (FE) head models opens vast new opportunities to better understand brain injury mechanisms. Recently, growing efforts have been made to integrate fiber orientation from diffusion tensor imaging (DTI) into FE models to predict white matter (WM) tract-related deformation that is biomechanically characterized by tract-related strains. Commonly used approaches often downsample the spatially enriched fiber orientation to match the FE resolution with one orientation per element (i.e., element-wise orientation implementation). However, the validity of such downsampling operation and corresponding influences on the computed tract-related strains remain elusive. To address this, the current study proposed a new approach to integrate voxel-wise fiber orientation from one DTI atlas (isotropic resolution of 1 mm(3)) into FE models by embedding orientations from multiple voxels within one element (i.e., voxel-wise orientation implementation). By setting the responses revealed by the newly proposed voxel-wise orientation implementation as the reference, we evaluated the reliability of two previous downsampling approaches by examining the downsampled fiber orientation and the computationally predicted tract-related strains secondary to one concussive impact. Two FE models with varying element sizes (i.e., 6.4 +/- 1.6 mm and 1.3 +/- 0.6 mm, respectively) were incorporated. The results showed that, for the model with a large voxelmesh resolution mismatch, the downsampled element-wise fiber orientation, with respect to its voxel-wise counterpart, exhibited an absolute deviation over 30 across the WM/gray matter interface and the pons regions. Accordingly, this orientation deviation compromised the computation of tract-related strains with normalized root-mean-square errors up to 30% and underestimated the peak tract-related strains up to 10%. For the other FE model with finer meshes, the downsampling-induced effects were lower, both on the fiber orientation and tract-related strains. Taken together, the voxel-wise orientation implementation is recommended in future studies as it leverages the DTI-delineated fiber orientation to a larger extent than the element-wise orientation implementation. Thus, this study yields novel insights on integrating neuroimaging-revealed fiber orientation into FE models and may better inform the computation of WM tract-related deformation.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
Finite element model, Diffusion tensor imaging, Resolution mismatch, Fiber orientation downsampling, White matter tract-related deformation
National Category
Cell and Molecular Biology Cancer and Oncology Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-314832 (URN)10.1016/j.jmbbm.2022.105294 (DOI)000807359000003 ()35636118 (PubMedID)2-s2.0-85131464532 (Scopus ID)
Note

QC 20220627

Available from: 2022-06-27 Created: 2022-06-27 Last updated: 2023-03-22Bibliographically approved
Huber, C. M., Patton, D. A., Maheshwari, J., Zhou, Z., Kleiven, S. & Arbogast, K. B. (2022). Finite Element Simulations of a Concussion Case in High School Soccer. In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI: . Paper presented at 2022 International Research Council on the Biomechanics of Injury, IRCOBI 2022, Porto, Portugal, 14 September 2022 through 16 September 2022 (pp. 616-617). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>Finite Element Simulations of a Concussion Case in High School Soccer
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2022 (English)In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2022, p. 616-617Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2022
National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-331253 (URN)2-s2.0-85139469443 (Scopus ID)
Conference
2022 International Research Council on the Biomechanics of Injury, IRCOBI 2022, Porto, Portugal, 14 September 2022 through 16 September 2022
Note

QC 20230706

Available from: 2023-07-06 Created: 2023-07-06 Last updated: 2023-07-06Bibliographically approved
Zhou, Z., Li, X., Domel, A. G., Dennis, E. L., Georgiadis, M., Liu, Y., . . . Zeineh, M. (2022). The Presence of the Temporal Horn Exacerbates the Vulnerability of Hippocampus During Head Impacts. Frontiers in Bioengineering and Biotechnology, 10, Article ID 754344.
Open this publication in new window or tab >>The Presence of the Temporal Horn Exacerbates the Vulnerability of Hippocampus During Head Impacts
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2022 (English)In: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 10, article id 754344Article in journal (Refereed) Published
Abstract [en]

Hippocampal injury is common in traumatic brain injury (TBI) patients, but the underlying pathogenesis remains elusive. In this study, we hypothesize that the presence of the adjacent fluid-containing temporal horn exacerbates the biomechanical vulnerability of the hippocampus. Two finite element models of the human head were used to investigate this hypothesis, one with and one without the temporal horn, and both including a detailed hippocampal subfield delineation. A fluid-structure interaction coupling approach was used to simulate the brain-ventricle interface, in which the intraventricular cerebrospinal fluid was represented by an arbitrary Lagrangian-Eulerian multi-material formation to account for its fluid behavior. By comparing the response of these two models under identical loadings, the model that included the temporal horn predicted increased magnitudes of strain and strain rate in the hippocampus with respect to its counterpart without the temporal horn. This specifically affected cornu ammonis (CA) 1 (CA1), CA2/3, hippocampal tail, subiculum, and the adjacent amygdala and ventral diencephalon. These computational results suggest that the presence of the temporal horn exacerbate the vulnerability of the hippocampus, highlighting the mechanobiological dependency of the hippocampus on the temporal horn.

Place, publisher, year, edition, pages
Frontiers Media SA, 2022
Keywords
hippocampal injury, temporal horn, brain-ventricle interface, fluid-structure interaction, finite element analysis, traumatic brain injury
National Category
Neurosciences
Identifiers
urn:nbn:se:kth:diva-311296 (URN)10.3389/fbioe.2022.754344 (DOI)000779534400001 ()35392406 (PubMedID)2-s2.0-85128175705 (Scopus ID)
Note

QC 20220421

Available from: 2022-04-21 Created: 2022-04-21 Last updated: 2022-06-25Bibliographically approved
Li, X., Zhou, Z. & Kleiven, S. (2021). An anatomically detailed and personalizable head injury model: Significance of brain and white matter tract morphological variability on strain. Biomechanics and Modeling in Mechanobiology
Open this publication in new window or tab >>An anatomically detailed and personalizable head injury model: Significance of brain and white matter tract morphological variability on strain
2021 (English)In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940Article in journal (Refereed) Published
Abstract [en]

Finite element head (FE) models are important numerical tools to study head injuries and develop protection systems. The generation of anatomically accurate and subject-specific head models with conforming hexahedral meshes remains a significant challenge. The focus of this study is to present two developmental works: first, an anatomically detailed FE head model with conforming hexahedral meshes that has smooth interfaces between the brain and the cerebrospinal fluid, embedded with white matter (WM) fiber tracts; second, a morphing approach for subject-specific head model generation via a new hierarchical image registration pipeline integrating Demons and Dramms deformable registration algorithms. The performance of the head model is evaluated by comparing model predictions with experimental data of brain–skull relative motion, brain strain, and intracranial pressure. To demonstrate the applicability of the head model and the pipeline, six subject-specific head models of largely varying intracranial volume and shape are generated, incorporated with subject-specific WM fiber tracts. DICE similarity coefficients for cranial, brain mask, local brain regions, and lateral ventricles are calculated to evaluate personalization accuracy, demonstrating the efficiency of the pipeline in generating detailed subject-specific head models achieving satisfactory element quality without further mesh repairing. The six head models are then subjected to the same concussive loading to study the sensitivity of brain strain to inter-subject variability of the brain and WM fiber morphology. The simulation results show significant differences in maximum principal strain and axonal strain in local brain regions (one-way ANOVA test, p < 0.001), as well as their locations also vary among the subjects, demonstrating the need to further investigate the significance of subject-specific models. The techniques developed in this study may contribute to better evaluation of individual brain injury and the development of individualized head protection systems in the future. This study also contains general aspects the research community may find useful: on the use of experimental brain strain close to or at injury level for head model validation; the hierarchical image registration pipeline can be used to morph other head models, such as smoothed-voxel models.

Place, publisher, year, edition, pages
Springer Science and Business Media Deutschland GmbH, 2021
Keywords
Axonal strain, Demons and Dramms image registration, Finite element analysis, Mesh morphing, Subject-specific head model, Traumatic brain injury, Brain, Cerebrospinal fluid, Image registration, Quality control, Deformable registration, Intra-cranial pressure, Maximum principal strain, Morphological variability, Research communities, Similarity coefficients, Subject specific models, White matter tracts, Pipelines
National Category
Other Medical Engineering Neurology
Identifiers
urn:nbn:se:kth:diva-285311 (URN)10.1007/s10237-020-01391-8 (DOI)000576877900001 ()33037509 (PubMedID)2-s2.0-85092542182 (Scopus ID)
Note

QC 20201202

Available from: 2020-12-02 Created: 2020-12-02 Last updated: 2024-01-09Bibliographically approved
Walsh, D. R., Ross, A. M., Newport, D. T., Zhou, Z., Kearns, J., Fearon, C., . . . Mulvihill, J. J. E. (2021). Mechanical characterisation of the human dura mater, falx cerebri and superior sagittal sinus. Acta Biomaterialia, 134, 388-400
Open this publication in new window or tab >>Mechanical characterisation of the human dura mater, falx cerebri and superior sagittal sinus
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2021 (English)In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 134, p. 388-400Article in journal (Refereed) Published
Abstract [en]

The cranial meninges have been shown to play a pivotal role in traumatic brain injury mechanopathology. However, while the mechanical response of the brain and its many subregions have been studied extensively, the meninges have conventionally been overlooked. This paper presents the first comparative mechanical analysis of human dura mater, falx cerebri and superior sagittal sinus tissues. Biaxial tensile analysis identified that these tissues are mechanically heterogeneous, in contrast to the assumption that the tissues are mechanically homogeneous which is typically employed in FE model design. A thickness of 0.91 +/- 0.05 (standard error) mm for the falx cerebri was also identified. This data can aid in improving the biofidelity of the influential falx structure in FE models. Additionally, the use of a collagen hybridizing peptide on the superior sagittal sinus suggests this structure is particularly susceptible to the effects of circumf erential stretch, which may have important implications for clinical treatment of dural venous sinus pathologies. Collectively, this research progresses understanding of meningeal mechanical and structural characteristics and may aid in elucidating the behaviour of these tissues in healthy and diseased conditions.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Traumatic brain injury (TBI), Biomechanics, Meninges, Collagen hybridizing peptide (CHP), Structural damage analysis
National Category
Physiology
Identifiers
urn:nbn:se:kth:diva-304703 (URN)10.1016/j.actbio.2021.07.043 (DOI)000709954800001 ()34314888 (PubMedID)2-s2.0-85111679607 (Scopus ID)
Note

QC 20211110

Available from: 2021-11-10 Created: 2021-11-10 Last updated: 2022-06-25Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-3910-0418

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