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Tripathi A, Wan Y, Malave S, Turcsanyi S, Fawzi AL, Brooks A, Kesari H, Snedden T, Ferrazzano P, Franck C, Carlsen RW. Laboratory Evaluation of a Wearable Instrumented Headband for Rotational Head Kinematics Measurement. Ann Biomed Eng 2025:10.1007/s10439-025-03746-7. [PMID: 40377738 DOI: 10.1007/s10439-025-03746-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2025] [Accepted: 04/27/2025] [Indexed: 05/18/2025]
Abstract
PURPOSE Mild traumatic brain injuries (mTBI) are a highly prevalent condition with heterogeneous outcomes between individuals. A key factor governing brain tissue deformation and the risk of mTBI is the rotational kinematics of the head. Instrumented mouthguards are a widely accepted method for measuring rotational head motions, owing to their robust sensor-skull coupling. However, wearing mouthguards is not feasible in all situations, especially for long-term data collection. Therefore, alternative wearable devices are needed. In this study, we present an improved design and data processing scheme for an instrumented headband. METHODS Our instrumented headband utilizes an array of inertial measurement units (IMUs) and a new data processing scheme based on continuous wavelet transforms to address sources of error in the IMU measurements. The headband performance was evaluated in the laboratory on an anthropomorphic test device, which was impacted with a soccer ball to replicate soccer heading. RESULTS When comparing the measured peak rotational velocities (PRV) and peak rotational accelerations (PRA) between the reference sensors and the headband for impacts to the front of the head, the correlation coefficients (r) were 0.80 and 0.63, and the normalized root mean square error (NRMSE) values were 0.20 and 0.28, respectively. However, when considering all impact locations, r dropped to 0.42 and 0.34 and NRMSE increased to 0.5 and 0.41 for PRV and PRA, respectively. CONCLUSION This new instrumented headband improves upon previous headband designs in reconstructing the rotational head kinematics resulting from frontal soccer ball impacts, providing a potential alternative to instrumented mouthguards.
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Affiliation(s)
- Anu Tripathi
- Department of Engineering, Robert Morris University, Moon Township, PA, USA
| | - Yang Wan
- School of Engineering, Brown University, Providence, RI, USA
| | | | - Sheila Turcsanyi
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Alice Lux Fawzi
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Alison Brooks
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA
| | - Haneesh Kesari
- School of Engineering, Brown University, Providence, RI, USA
| | - Traci Snedden
- School of Nursing, University of Wisconsin-Madison, Madison, WI, USA
| | - Peter Ferrazzano
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI, USA
| | - Christian Franck
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Rika Wright Carlsen
- Department of Engineering, Robert Morris University, Moon Township, PA, USA.
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2
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Pitti E, Herling L, Li X, Ajne G, Larsson M. Experimental Assessment of Traction Force and Associated Fetal Brain Deformation in Vacuum-Assisted Delivery. Ann Biomed Eng 2025; 53:825-844. [PMID: 39710825 PMCID: PMC11929728 DOI: 10.1007/s10439-024-03665-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 12/02/2024] [Indexed: 12/24/2024]
Abstract
Vacuum-assisted delivery (VAD) uses a vacuum cup on the fetal scalp to apply traction during uterine contractions, assisting complicated vaginal deliveries. Despite its widespread use, VAD presents a higher risk of neonatal morbidity compared to natural vaginal delivery and biomechanical evidence for safe VAD traction forces is still limited. The aim of this study is to develop and assess the feasibility of an experimental VAD testing setup, and investigate the impact of traction forces on fetal brain deformation. A patient-specific fetal head phantom was developed and subjected to experimental VAD in two testing setups: one with manual and one with automatic force application. The skull phantom was 3D printed using multi-material Polyjet technology. The brain phantom was cast in a 3D-printed mold using a composite hydrogel, and sonomicrometry crystals were used to estimate the brain deformation in three brain regions. The experimental VADs on the fetal head phantom allowed for quantifying brain strain with traction forces up to 112 N. Consistent brain crystal movements aligned with the traction force demonstrated the feasibility of the setup. The estimated brain deformations reached up to 4% and correlated significantly with traction force (p < 0.05) in regions close to the suction cup. Despite limitations such as the absence of scalp modeling and a simplified strain computation, this study provides a baseline for numerical studies and supports further research to optimize the safety of VAD procedures and develop VAD training platforms.
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Affiliation(s)
- Estelle Pitti
- Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden.
- Clinical Science Intervention and Technology-CLINTEC, Karolinska Institutet, Stockholm, Sweden.
| | - Lotta Herling
- Clinical Science Intervention and Technology-CLINTEC, Karolinska Institutet, Stockholm, Sweden
- Pregnancy Care & Delivery, Karolinska University Hospital, Stockholm, Sweden
| | - Xiaogai Li
- Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Gunilla Ajne
- Clinical Science Intervention and Technology-CLINTEC, Karolinska Institutet, Stockholm, Sweden
- Pregnancy Care & Delivery, Karolinska University Hospital, Stockholm, Sweden
| | - Matilda Larsson
- Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden
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Arani AHG, Okamoto RJ, Escarcega JD, Jerusalem A, Alshareef AA, Bayly PV. Full-field, frequency-domain comparison of simulated and measured human brain deformation. Biomech Model Mechanobiol 2025; 24:331-346. [PMID: 39704895 DOI: 10.1007/s10237-024-01913-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Accepted: 11/16/2024] [Indexed: 12/21/2024]
Abstract
We propose a robust framework for quantitatively comparing model-predicted and experimentally measured strain fields in the human brain during harmonic skull motion. Traumatic brain injuries (TBIs) are typically caused by skull impact or acceleration, but how skull motion leads to brain deformation and consequent neural injury remains unclear and comparison of model predictions to experimental data remains limited. Magnetic resonance elastography (MRE) provides high-resolution, full-field measurements of dynamic brain deformation induced by harmonic skull motion. In the proposed framework, full-field strain measurements from human brain MRE in vivo are compared to simulated strain fields from models with similar harmonic loading. To enable comparison, the model geometry and subject anatomy, and subsequently, the predicted and measured strain fields are nonlinearly registered to the same standard brain atlas. Strain field correlations ( C v ), both global (over the brain volume) and local (over smaller sub-volumes), are then computed from the inner product of the complex-valued strain tensors from model and experiment at each voxel. To demonstrate our approach, we compare strain fields from MRE in six human subjects to predictions from two previously developed models. Notably, global C v values are higher when comparing strain fields from different subjects ( C v ~0.6-0.7) than when comparing strain fields from either of the two models to strain fields in any subject. The proposed framework provides a quantitative method to assess similarity (and to identify discrepancies) between model predictions and experimental measurements of brain deformation and thus can aid in the development and evaluation of improved models of brain biomechanics.
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Affiliation(s)
- Amir H G Arani
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, USA
| | - Ruth J Okamoto
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, USA
| | - Jordan D Escarcega
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, USA
| | - Antoine Jerusalem
- Department of Engineering Science, University of Oxford, Oxford, OX1 3PJ, UK
| | - Ahmed A Alshareef
- Department of Mechanical Engineering, University of South Carolina, Columbia, SC, USA
| | - Philip V Bayly
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, USA.
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Zhan X, Zhou Z, Liu Y, Cecchi NJ, Hajiahamemar M, Zeineh MM, Grant GA, Camarillo D. Differences between two maximal principal strain rate calculation schemes in traumatic brain analysis with in-vivo and in-silico datasets. J Biomech 2025; 179:112456. [PMID: 39671828 DOI: 10.1016/j.jbiomech.2024.112456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 10/05/2024] [Accepted: 12/02/2024] [Indexed: 12/15/2024]
Abstract
Brain deformation caused by a head impact leads to traumatic brain injury (TBI). The maximum principal strain (MPS) was used to measure the extent of brain deformation and predict injury, and the recent evidence has indicated that incorporating the maximum principal strain rate (MPSR) and the product of MPS and MPSR, denoted as MPS × SR, enhances the accuracy of TBI prediction. However, ambiguities have arisen about the calculation of MPSR. Two schemes have been utilized: one is to use the time derivative of MPS (MPSR1), and another is to use the first eigenvalue of the strain rate tensor (MPSR2). Both MPSR1 and MPSR2 have been applied in previous studies to predict TBI. To quantify the discrepancies between these two methodologies, we compared them across eight in-vivo and one in-silico head impact datasets and found that 95MPSR1 was slightly larger than 95MPSR2 and 95MPS × SR1 was 4.85 % larger than 95MPS × SR2 in average. Across every element in all head impacts, the average MPSR1 was 12.73 % smaller than MPSR2, and MPS × SR1 was 11.95 % smaller than MPS × SR2. Furthermore, logistic regression models were trained to predict TBI using MPSR (or MPS × SR), and no significant difference was observed in the predictability. The consequence of misuse of MPSR and MPS × SR thresholds (i.e. compare threshold of 95MPSR1 with value from 95MPSR2 to determine if the impact is injurious) was investigated, and the resulting false rates were found to be around 1 %. The evidence suggested that these two methodologies were not significantly different in detecting TBI.
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Affiliation(s)
- Xianghao Zhan
- Department of Bioengineering, Stanford University, CA, 94305, USA
| | - Zhou Zhou
- Department of Bioengineering, Stanford University, CA, 94305, USA; Division of Neuronic Engineering, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Yuzhe Liu
- School of Biological Science and Medical Engineering, Beihang University, Beijing 10019, China; Department of Bioengineering, Stanford University, CA, 94305, USA.
| | | | - Marzieh Hajiahamemar
- Department of Biomedical Engineering & Chemical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | | | - Gerald A Grant
- Department of Radiology, Stanford University, CA 94305, USA; Department of Neurology, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Duke University, Durham, NC 27710, USA
| | - David Camarillo
- Department of Bioengineering, Stanford University, CA, 94305, USA; Department of Neurology, Stanford University, Stanford, CA 94305, USA; Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
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Tierney G. Concussion biomechanics, head acceleration exposure and brain injury criteria in sport: a review. Sports Biomech 2024; 23:1888-1916. [PMID: 34939531 DOI: 10.1080/14763141.2021.2016929] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/05/2021] [Indexed: 10/19/2022]
Abstract
There are mounting concerns surrounding the risk of neurodegenerative diseases and complications associated with concussion incidence and repetitive head acceleration events (HAE) in sport. The aim of this review is to provide an overview of concussion biomechanics, head acceleration exposure and brain injury criteria in sport. Rotational head motion appears to be the primary contributor to brain injury risk due to the unique mechanical properties of the brain and its location within the body. There is a growing evidence base of different biomechanical brain injury mechanisms, including those involving repetitive HAE. Historically, many studies on concussion biomechanics, head acceleration exposure and brain injury criteria in sport have been limited by validity of the biomechanical approaches undertaken. Biomechanical approaches such as instrumented mouthguards and subject-specific finite element (FE) brain models provide a unique opportunity to develop greater brain injury criteria and aid in on-field athlete removal. Implementing these approaches on a large-scale can gain insight into potential risk factors within sports and certain athletes/cohorts who sustain a greater number and/or severity of HAE throughout their playing career. These findings could play a key role in the development of concussion prevention strategies and techniques that mitigate the severity of HAE in sport.
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Affiliation(s)
- Gregory Tierney
- Sport and Exercise Sciences Research Institute, School of Sport, Faculty of Life and Health Sciences, Ulster University, Belfast, UK
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Lin N, Wu S, Wu Z, Ji S. Efficient Generation of Pretraining Samples for Developing a Deep Learning Brain Injury Model via Transfer Learning. Ann Biomed Eng 2024; 52:2726-2740. [PMID: 37642795 DOI: 10.1007/s10439-023-03354-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/18/2023] [Indexed: 08/31/2023]
Abstract
The large amount of training samples required to develop a deep learning brain injury model demands enormous computational resources. Here, we study how a transformer neural network (TNN) of high accuracy can be used to efficiently generate pretraining samples for a convolutional neural network (CNN) brain injury model to reduce computational cost. The samples use synthetic impacts emulating real-world events or augmented impacts generated from limited measured impacts. First, we verify that the TNN remains highly accurate for the two impact types (N = 100 each;R 2 of 0.948-0.967 with root mean squared error, RMSE, ~ 0.01, for voxelized peak strains). The TNN-estimated samples (1000-5000 for each data type) are then used to pretrain a CNN, which is further finetuned using directly simulated training samples (250-5000). An independent measured impact dataset considered of complete capture of impact event is used to assess estimation accuracy (N = 191). We find that pretraining can significantly improve CNN accuracy via transfer learning compared to a baseline CNN without pretraining. It is most effective when the finetuning dataset is relatively small (e.g., 2000-4000 pretraining synthetic or augmented samples improves success rate from 0.72 to 0.81 with 500 finetuning samples). When finetuning samples reach 3000 or more, no obvious improvement occurs from pretraining. These results support using the TNN to rapidly generate pretraining samples to facilitate a more efficient training strategy for future deep learning brain models, by limiting the number of costly direct simulations from an alternative baseline model. This study could contribute to a wider adoption of deep learning brain injury models for large-scale predictive modeling and ultimately, enhancing safety protocols and protective equipment.
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Affiliation(s)
- Nan Lin
- Department of Biomedical Engineering, Worcester Polytechnic Institute, 60 Prescott Street, Worcester, MA, 01605, USA
| | - Shaoju Wu
- Department of Biomedical Engineering, Worcester Polytechnic Institute, 60 Prescott Street, Worcester, MA, 01605, USA
| | - Zheyang Wu
- Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - Songbai Ji
- Department of Biomedical Engineering, Worcester Polytechnic Institute, 60 Prescott Street, Worcester, MA, 01605, USA.
- Department of Mechanical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609, USA.
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Cecchi NJ, Callan AA, Watson LP, Liu Y, Zhan X, Vegesna RV, Pang C, Le Flao E, Grant GA, Zeineh MM, Camarillo DB. Padded Helmet Shell Covers in American Football: A Comprehensive Laboratory Evaluation with Preliminary On-Field Findings. Ann Biomed Eng 2024; 52:2703-2716. [PMID: 36917295 PMCID: PMC10013271 DOI: 10.1007/s10439-023-03169-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/08/2023] [Indexed: 03/15/2023]
Abstract
Protective headgear effects measured in the laboratory may not always translate to the field. In this study, we evaluated the impact attenuation capabilities of a commercially available padded helmet shell cover in the laboratory and on the field. In the laboratory, we evaluated the padded helmet shell cover's efficacy in attenuating impact magnitude across six impact locations and three impact velocities when equipped to three different helmet models. In a preliminary on-field investigation, we used instrumented mouthguards to monitor head impact magnitude in collegiate linebackers during practice sessions while not wearing the padded helmet shell covers (i.e., bare helmets) for one season and whilst wearing the padded helmet shell covers for another season. The addition of the padded helmet shell cover was effective in attenuating the magnitude of angular head accelerations and two brain injury risk metrics (DAMAGE, HARM) across most laboratory impact conditions, but did not significantly attenuate linear head accelerations for all helmets. Overall, HARM values were reduced in laboratory impact tests by an average of 25% at 3.5 m/s (range: 9.7 to 39.6%), 18% at 5.5 m/s (range: - 5.5 to 40.5%), and 10% at 7.4 m/s (range: - 6.0 to 31.0%). However, on the field, no significant differences in any measure of head impact magnitude were observed between the bare helmet impacts and padded helmet impacts. Further laboratory tests were conducted to evaluate the ability of the padded helmet shell cover to maintain its performance after exposure to repeated, successive impacts and across a range of temperatures. This research provides a detailed assessment of padded helmet shell covers and supports the continuation of in vivo helmet research to validate laboratory testing results.
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Affiliation(s)
- Nicholas J Cecchi
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Ashlyn A Callan
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Landon P Watson
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Yuzhe Liu
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Xianghao Zhan
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Ramanand V Vegesna
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Collin Pang
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Enora Le Flao
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Gerald A Grant
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
- Department of Neurology, Stanford University, Stanford, CA, 94305, USA
- Department of Neurosurgery, Duke University, Durham, NC, 27710, USA
| | - Michael M Zeineh
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - David B Camarillo
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA.
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA.
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Stitt D, Kabaliuk N, Alexander K, Draper N. Potential of Soft-Shelled Rugby Headgear to Lower Regional Brain Strain Metrics During Standard Drop Tests. SPORTS MEDICINE - OPEN 2024; 10:102. [PMID: 39333426 PMCID: PMC11436562 DOI: 10.1186/s40798-024-00744-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 06/24/2024] [Indexed: 09/29/2024]
Abstract
BACKGROUND The growing concern for player safety in rugby has led to an increased focus on head impacts. Previous laboratory studies have shown that rugby headgear significantly reduces peak linear and rotational accelerations compared to no headgear. However, these metrics may have limited relevance in assessing the effectiveness of headgear in preventing strain-based brain injuries like concussions. This study used an instantaneous deep-learning brain injury model to quantify regional brain strain mitigation of rugby headgear during drop tests. Tests were conducted on flat and angled impact surfaces across different heights, using a Hybrid III headform and neck. RESULTS Headgear presence generally reduced the peak rotational velocities, with some headgear outperforming others. However, the effect on peak regional brain strains was less consistent. Of the 5 headgear tested, only the newer models that use open cell foams at densities above 45 kg/m3 consistently reduced the peak strain in the cerebrum, corpus callosum, and brainstem. The 3 conventional headgear that use closed cell foams at or below 45 kg/m3 showed no consistent reduction in the peak strain in the cerebrum, corpus callosum, and brainstem. CONCLUSIONS The presence of rugby headgear may be able to reduce the severity of head impact exposure during rugby. However, to understand how these findings relate to brain strain mitigation in the field, further investigation into the relationship between the impact conditions in this study and those encountered during actual gameplay is necessary.
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Affiliation(s)
- Danyon Stitt
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
- University of Canterbury, Sports Health and Rehabilitation Research Center (SHARRC), Christchurch, 8041, New Zealand
| | - Natalia Kabaliuk
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand.
- University of Canterbury, Sports Health and Rehabilitation Research Center (SHARRC), Christchurch, 8041, New Zealand.
| | - Keith Alexander
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | - Nick Draper
- University of Canterbury, Sports Health and Rehabilitation Research Center (SHARRC), Christchurch, 8041, New Zealand
- Faculty of Health, University of Canterbury, Christchurch, 8041, New Zealand
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Zhan X, Liu Y, Cecchi NJ, Callan AA, Le Flao E, Gevaert O, Zeineh MM, Grant GA, Camarillo DB. AI-Based Denoising of Head Impact Kinematics Measurements With Convolutional Neural Network for Traumatic Brain Injury Prediction. IEEE Trans Biomed Eng 2024; 71:2759-2770. [PMID: 38683703 DOI: 10.1109/tbme.2024.3392537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
OBJECTIVE Wearable devices are developed to measure head impact kinematics but are intrinsically noisy because of the imperfect interface with human bodies. This study aimed to improve the head impact kinematics measurements obtained from instrumented mouthguards using deep learning to enhance traumatic brain injury (TBI) risk monitoring. METHODS We developed one-dimensional convolutional neural network (1D-CNN) models to denoise mouthguard kinematics measurements for tri-axial linear acceleration and tri-axial angular velocity from 163 laboratory dummy head impacts. The performance of the denoising models was evaluated on three levels: kinematics, brain injury criteria, and tissue-level strain and strain rate. Additionally, we performed a blind test on an on-field dataset of 118 college football impacts and a test on 413 post-mortem human subject (PMHS) impacts. RESULTS On the dummy head impacts, the denoised kinematics showed better correlation with reference kinematics, with relative reductions of 36% for pointwise root mean squared error and 56% for peak absolute error. Absolute errors in six brain injury criteria were reduced by a mean of 82%. For maximum principal strain and maximum principal strain rate, the mean error reduction was 35% and 69%, respectively. On the PMHS impacts, similar denoising effects were observed and the peak kinematics after denoising were more accurate (relative error reduction for 10% noisiest impacts was 75.6%). CONCLUSION The 1D-CNN denoising models effectively reduced errors in mouthguard-derived kinematics measurements on dummy and PMHS impacts. SIGNIFICANCE This study provides a novel approach for denoising head kinematics measurements in dummy and PMHS impacts, which can be further validated on more real-human kinematics data before real-world applications.
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Arani AH, Okamoto RJ, Escarcega JD, Jerusalem A, Alshareef AA, Bayly PV. Full-field, frequency-domain comparison of simulated and measured human brain deformation. RESEARCH SQUARE 2024:rs.3.rs-4765592. [PMID: 39184071 PMCID: PMC11343286 DOI: 10.21203/rs.3.rs-4765592/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
We propose a robust framework for quantitatively comparing model-predicted and experimentally measured strain fields in the human brain during harmonic skull motion. Traumatic brain injuries (TBIs) are typically caused by skull impact or acceleration, but how skull motion leads to brain deformation and consequent neural injury remains unclear and comparison of model predictions to experimental data remains limited. Magnetic resonance elastography (MRE) provides high-resolution, full-field measurements of dynamic brain deformation induced by harmonic skull motion. In the proposed framework, full-field strain measurements from human brain MRE in vivo are compared to simulated strain fields from models with similar harmonic loading. To enable comparison, the model geometry and subject anatomy, and subsequently, the predicted and measured strain fields are nonlinearly registered to the same standard brain atlas. Strain field correlations (\(\:{C}_{v}\)), both global (over the brain volume) and local (over smaller sub-volumes), are then computed from the inner product of the complex-valued strain tensors from model and experiment at each voxel. To demonstrate our approach, we compare strain fields from MRE in six human subjects to predictions from two previously developed models. Notably, global \(\:{C}_{v}\) values are higher when comparing strain fields from different subjects (\(\:{C}_{v}\)~0.6-0.7) than when comparing strain fields from either of the two models to strain fields in any subject. The proposed framework provides a quantitative method to assess similarity (and to identify discrepancies) between model predictions and experimental measurements of brain deformation, and thus can aid in the development and evaluation of improved models of brain biomechanics.
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11
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Stilwell G, Stitt D, Alexander K, Draper N, Kabaliuk N. The Impact of Drop Test Conditions on Brain Strain Location and Severity: A Novel Approach Using a Deep Learning Model. Ann Biomed Eng 2024; 52:2234-2246. [PMID: 38739210 PMCID: PMC11247052 DOI: 10.1007/s10439-024-03525-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/23/2024] [Indexed: 05/14/2024]
Abstract
In contact sports such as rugby, players are at risk of sustaining traumatic brain injuries (TBI) due to high-intensity head impacts that generate high linear and rotational accelerations of the head. Previous studies have established a clear link between high-intensity head impacts and brain strains that result in concussions. This study presents a novel approach to investigating the effect of a range of laboratory controlled drop test parameters on regional peak and mean maximum principal strain (MPS) predictions within the brain using a trained convolutional neural network (CNN). The CNN is publicly available at https://github.com/Jilab-biomechanics/CNN-brain-strains . The results of this study corroborate previous findings that impacts to the side of the head result in significantly higher regional MPS than forehead impacts. Forehead impacts tend to result in the lowest region-averaged MPS values for impacts where the surface angle was at 0° and 45°, while side impacts tend to result in higher regional peak and mean MPS. The absence of a neck in drop tests resulted in lower regional peak and mean MPS values. The results indicated that the relationship between drop test parameters and resulting regional peak and mean MPS predictions is complex. The study's findings offer valuable insights into how deep learning models can be used to provide more detailed insights into how drop test conditions impact regional MPS. The novel approach used in this paper to predict brain strains can be applied in the development of better methods to reduce the brain strain resulting from head accelerations such as protective sports headgear.
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Affiliation(s)
- George Stilwell
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | - Danyon Stitt
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | - Keith Alexander
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | - Nick Draper
- Faculty of Health, University of Canterbury, Christchurch, 8041, New Zealand
| | - Natalia Kabaliuk
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand.
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12
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Zhan X, Liu Y, Cecchi NJ, Gevaert O, Zeineh MM, Grant GA, Camarillo DB. Brain Deformation Estimation With Transfer Learning for Head Impact Datasets Across Impact Types. IEEE Trans Biomed Eng 2024; 71:1853-1863. [PMID: 38224520 DOI: 10.1109/tbme.2024.3354192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
OBJECTIVE The machine-learning head model (MLHM) to accelerate the calculation of brain strain and strain rate, which are the predictors for traumatic brain injury (TBI), but the model accuracy was found to decrease sharply when the training/test datasets were from different head impacts types (i.e., car crash, college football), which limits the applicability of MLHMs to different types of head impacts and sports. Particularly, small sizes of target dataset for specific impact types with tens of impacts may not be enough to train an accurate impact-type-specific MLHM. METHODS To overcome this, we propose data fusion and transfer learning to develop a series of MLHMs to predict the maximum principal strain (MPS) and maximum principal strain rate (MPSR). RESULTS The strategies were tested on American football (338), mixed martial arts (457), reconstructed car crash (48) and reconstructed American football (36) and we found that the MLHMs developed with transfer learning are significantly more accurate in estimating MPS and MPSR than other models, with a mean absolute error (MAE) smaller than 0.03 in predicting MPS and smaller than [Formula: see text] in predicting MPSR on all target impact datasets. High performance in concussion detection was observed based on the MPS and MPSR estimated by the transfer-learning-based models. CONCLUSION The MLHMs can be applied to various head impact types for rapidly and accurately calculating brain strain and strain rate. SIGNIFICANCE This study enables developing MLHMs for the head impact type with limited availability of data, and will accelerate the applications of MLHMs.
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Zhan X, Sun J, Liu Y, Cecchi NJ, Le Flao E, Gevaert O, Zeineh MM, Camarillo DB. Adaptive Machine Learning Head Model Across Different Head Impact Types Using Unsupervised Domain Adaptation and Generative Adversarial Networks. IEEE SENSORS JOURNAL 2024; 24:7097-7106. [PMID: 39897708 PMCID: PMC11781752 DOI: 10.1109/jsen.2023.3349213] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2025]
Abstract
Machine learning head models (MLHMs) are developed to estimate brain deformation from sensor-based kinematics for early detection of traumatic brain injury (TBI). However, the overfitting to simulated impacts and the decreasing accuracy caused by distributional shift of different head impact datasets hinders the broad clinical applications of current MLHMs. We propose a new MLHM configuration that integrates unsupervised domain adaptation with a deep neural network to predict whole-brain maximum principal strain (MPS) and MPS rate (MPSR). With 12,780 simulated head impacts, we performed unsupervised domain adaptation on target head impacts from 302 college football (CF) impacts and 457 mixed martial arts (MMA) impacts using domain regularized component analysis (DRCA) and cycle-GAN-based methods. The new model improved the MPS/MPSR estimation accuracy, with the DRCA method outperforming other domain adaptation methods in prediction accuracy: MPS mean absolute error (MAE): 0.017 (CF) and 0.020 (MMA); MPSR MAE: 4.09 s-1 (CF) and 6.61 s-1(MMA). On another two hold-out test sets with 195 college football impacts and 260 boxing impacts, the DRCA model outperformed the baseline model without domain adaptation in MPS and MPSR estimation MAE. The DRCA domain adaptation approach reduces the error of MPS/MPSR estimation to be well below previously reported TBI thresholds, enabling accurate brain deformation estimation to detect TBI in future clinical applications.
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Affiliation(s)
- Xianghao Zhan
- Department of Bioengineering, Stanford University, CA, 94305, USA
| | - Jiawei Sun
- Department of Bioengineering, Stanford University, CA, 94305, USA
| | - Yuzhe Liu
- School of Biological Science and Medical Engineering, BeiHang University, Beijing, 10019, China
| | | | - Enora Le Flao
- Department of Bioengineering, Stanford University, CA, 94305, USA
| | - Olivier Gevaert
- Department of Biomedical Data Science, Stanford University, CA, 94305, USA
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Bussey MD, Salmon D, Romanchuk J, Nanai B, Davidson P, Tucker R, Falvey E. Head Acceleration Events in Male Community Rugby Players: An Observational Cohort Study across Four Playing Grades, from Under-13 to Senior Men. Sports Med 2024; 54:517-530. [PMID: 37676621 PMCID: PMC10933157 DOI: 10.1007/s40279-023-01923-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2023] [Indexed: 09/08/2023]
Abstract
OBJECTIVES The aim of this study was to examine the cumulative head acceleration event (HAE) exposure in male rugby players from the Under-13 (U13) to senior club level over 4 weeks of matches and training during the 2021 community rugby season. METHODS This prospective, observational cohort study involved 328 male rugby players. Players were representative of four playing grades: U13 (N = 60, age 12.5 ± 0.6 years), U15 (N = 100, age 14.8 ± 0.9 years), U19 (N = 78, age 16.9 ± 0.7 years) and Premier senior men (N = 97, age 22.5 ± 3.1 years). HAE exposure was tracked across 48 matches and 113 training sessions. HAEs were recorded using boil-and-bite instrumented mouthguards (iMGs). The study assessed the incidence and prevalence of HAEs by ages, playing positions, and session types (match or training). RESULTS For all age grades, weekly match HAE incidence was highest at lower magnitudes (10-29 g). Proportionally, younger players experienced higher weekly incidence rates during training. The U19 players had 1.36 times the risk of high-magnitude (> 30 g) events during matches, while the U13 players had the lowest risk compared with all other grades. Tackles and rucks accounted for the largest HAE burden during matches, with forwards having 1.67 times the risk of > 30 g HAEs in rucks compared with backs. CONCLUSIONS This study provides novel data on head accelerations during rugby matches and training. The findings have important implications for identifying populations at greatest risk of high cumulative and acute head acceleration. Findings may guide training load management and teaching of skill execution in high-risk activities, particularly for younger players who may be exposed to proportionally more contact during training and for older players during matches.
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Affiliation(s)
- Melanie D Bussey
- School of Physical Education, Sports and Exercise Sciences, University of Otago, Dunedin, New Zealand.
| | | | - Janelle Romanchuk
- School of Physical Education, Sports and Exercise Sciences, University of Otago, Dunedin, New Zealand
- New Zealand Rugby, Wellington, New Zealand
| | - Bridie Nanai
- School of Physical Education, Sports and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Peter Davidson
- School of Physical Education, Sports and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Ross Tucker
- Institute of Sport and Exercise Medicine, University of Stellenbosch, Stellenbosch, South Africa
- World Rugby, Dublin, Ireland
| | - Eanna Falvey
- World Rugby, Dublin, Ireland
- School of Medicine & Health, University College Cork, Cork, Ireland
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Zhan X, Li Y, Liu Y, Cecchi NJ, Raymond SJ, Zhou Z, Vahid Alizadeh H, Ruan J, Barbat S, Tiernan S, Gevaert O, Zeineh MM, Grant GA, Camarillo DB. Machine-learning-based head impact subtyping based on the spectral densities of the measurable head kinematics. JOURNAL OF SPORT AND HEALTH SCIENCE 2023; 12:619-629. [PMID: 36921692 PMCID: PMC10466194 DOI: 10.1016/j.jshs.2023.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/06/2022] [Accepted: 02/16/2023] [Indexed: 05/26/2023]
Abstract
BACKGROUND Traumatic brain injury can be caused by head impacts, but many brain injury risk estimation models are not equally accurate across the variety of impacts that patients may undergo, and the characteristics of different types of impacts are not well studied. We investigated the spectral characteristics of different head impact types with kinematics classification. METHODS Data were analyzed from 3262 head impacts from lab reconstruction, American football, mixed martial arts, and publicly available car crash data. A random forest classifier with spectral densities of linear acceleration and angular velocity was built to classify head impact types (e.g., football, car crash, mixed martial arts). To test the classifier robustness, another 271 lab-reconstructed impacts were obtained from 5 other instrumented mouthguards. Finally, with the classifier, type-specific, nearest-neighbor regression models were built for brain strain. RESULTS The classifier reached a median accuracy of 96% over 1000 random partitions of training and test sets. The most important features in the classification included both low- and high-frequency features, both linear acceleration features and angular velocity features. Different head impact types had different distributions of spectral densities in low- and high-frequency ranges (e.g., the spectral densities of mixed martial arts impacts were higher in the high-frequency range than in the low-frequency range). The type-specific regression showed a generally higher R2 value than baseline models without classification. CONCLUSION The machine-learning-based classifier enables a better understanding of the impact kinematics spectral density in different sports, and it can be applied to evaluate the quality of impact-simulation systems and on-field data augmentation.
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Affiliation(s)
- Xianghao Zhan
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Yiheng Li
- Department of Biomedical Data Science, Stanford University, Stanford, CA 94305, USA
| | - Yuzhe Liu
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
| | - Nicholas J Cecchi
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Samuel J Raymond
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Zhou Zhou
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | | | - Jesse Ruan
- Ford Motor Company, 3001 Miller Rd, Dearborn, MI 48120, USA
| | - Saeed Barbat
- Ford Motor Company, 3001 Miller Rd, Dearborn, MI 48120, USA
| | | | - Olivier Gevaert
- Department of Biomedical Data Science, Stanford University, Stanford, CA 94305, USA
| | - Michael M Zeineh
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Gerald A Grant
- Department of Neurosurgery, Stanford University, Stanford, CA 94305, USA
| | - David B Camarillo
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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Menghani RR, Das A, Kraft RH. A sensor-enabled cloud-based computing platform for computational brain biomechanics. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 233:107470. [PMID: 36958108 DOI: 10.1016/j.cmpb.2023.107470] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 02/24/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND AND OBJECTIVES Driven by the risk of repetitive head trauma, sensors have been integrated into mouthguards to measure head impacts in contact sports and military activities. These wearable devices, referred to as "instrumented" or "smart" mouthguards are being actively developed by various research groups and organizations. These instrumented mouthguards provide an opportunity to further study and understand the brain biomechanics due to impact. In this study, we present a brain modeling service that can use information from these sensors to predict brain injury metrics in an automated fashion. METHODS We have built a brain modeling platform using several of Amazon's Web Services (AWS) to enable cloud computing and scalability. We use a custom-built cloud-based finite element modeling code to compute the physics-based nonlinear response of the intracranial brain tissue and provide a frontend web application and an application programming interface for groups working on head impact sensor technology to include simulated injury predictions into their research pipeline. RESULTS The platform results have been validated against experimental data available in literature for brain-skull relative displacements, brain strains and intracranial pressure. The parallel processing capability of the platform has also been tested and verified. We also studied the accuracy of the custom head surfaces generated by Avatar 3D. CONCLUSION We present a validated cloud-based computational brain modeling platform that uses sensor data as input for numerical brain models and outputs a quantitative description of brain tissue strains and injury metrics. The platform is expected to generate transparent, reproducible, and traceable brain computing results.
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Affiliation(s)
- Ritika R Menghani
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, 16802, USA
| | - Anil Das
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, 16802, USA
| | - Reuben H Kraft
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, 16802, USA; Department of Biomedical Engineering, The Pennsylvania State University, University Park, 16802, USA; Institute for Computational and Data Sciences, The Pennsylvania State University, University Park, 16802, USA.
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Zhan X, Liu Y, Cecchi NJ, Gevaert O, Zeineh MM, Grant GA, Camarillo DB. Finding the Spatial Co-Variation of Brain Deformation With Principal Component Analysis. IEEE Trans Biomed Eng 2022; 69:3205-3215. [PMID: 35349430 PMCID: PMC9580615 DOI: 10.1109/tbme.2022.3163230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Strain and strain rate are effective traumatic brain injury metrics. In finite element (FE) head model, thousands of elements were used to represent the spatial distribution of these metrics. Owing that these metrics are resulted from brain inertia, their spatial distribution can be represented in more concise pattern. Since head kinematic features and brain deformation vary largely across head impact types (Zhan et al., 2021), we applied principal component analysis (PCA) to find the spatial co-variation of injury metrics (maximum principal strain (MPS), MPS rate (MPSR) and MPS × MPSR) in four impact types: simulation, football, mixed martial arts and car crashes, and used the PCA to find patterns in these metrics and improve the machine learning head model (MLHM). METHODS We applied PCA to decompose the injury metrics for all impacts in each impact type, and investigate the spatial co-variation using the first principal component (PC1). Furthermore, we developed a MLHM to predict PC1 and then inverse-transform to predict for all brain elements. The accuracy, the model complexity and the size of training dataset of PCA-MLHM are compared with previous MLHM (Zhan et al., 2021). RESULTS PC1 explained variance on the datasets. Based on PC1 coefficients, the corpus callosum and midbrain exhibit high variance on all datasets. Finally, the PCA-MLHM reduced model parameters by 74% with a similar MPS estimation accuracy. CONCLUSION The brain injury metric in a dataset can be decomposed into mean components and PC1 with high explained variance. SIGNIFICANCE The spatial co-variation analysis enables better interpretation of the patterns in brain injury metrics. It also improves the efficiency of MLHM.
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Zhan X, Li Y, Liu Y, Cecchi NJ, Gevaert O, Zeineh MM, Grant GA, Camarillo DB. Piecewise Multivariate Linearity Between Kinematic Features and Cumulative Strain Damage Measure (CSDM) Across Different Types of Head Impacts. Ann Biomed Eng 2022; 50:1596-1607. [PMID: 35922726 DOI: 10.1007/s10439-022-03020-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022]
Abstract
In a previous study, we found that the relationship between brain strain and kinematic features cannot be described by a generalized linear model across different types of head impacts. In this study, we investigate if such a linear relationship exists when partitioning head impacts using a data-driven approach. We applied the K-means clustering method to partition 3161 impacts from various sources including simulation, college football, mixed martial arts, and car crashes. We found piecewise multivariate linearity between the cumulative strain damage (CSDM; assessed at the threshold of 0.15) and head kinematic features. Compared with the linear regression models without partition and the partition according to the types of head impacts, K-means-based data-driven partition showed significantly higher CSDM regression accuracy, which suggested the presence of piecewise multivariate linearity across types of head impacts. Additionally, we compared the piecewise linearity with the partitions based on individual features used in clustering. We found that the partition with maximum angular acceleration magnitude at 4706 rad/s2 led to the highest piecewise linearity. This study may contribute to an improved method for the rapid prediction of CSDM in the future.
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Affiliation(s)
- Xianghao Zhan
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Yiheng Li
- Department of Biomedical Data Science, Stanford University, Stanford, CA, 94305, USA
| | - Yuzhe Liu
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.
| | - Nicholas J Cecchi
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Olivier Gevaert
- Department of Biomedical Data Science, Stanford University, Stanford, CA, 94305, USA.,Stanford Center for Biomedical Informatics Research, Stanford University, Stanford, CA, 94305, USA
| | - Michael M Zeineh
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Gerald A Grant
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - David B Camarillo
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
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Predictive Factors of Kinematics in Traumatic Brain Injury from Head Impacts Based on Statistical Interpretation. Ann Biomed Eng 2021; 49:2901-2913. [PMID: 34244908 DOI: 10.1007/s10439-021-02813-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/10/2021] [Indexed: 02/08/2023]
Abstract
Brain tissue deformation resulting from head impacts is primarily caused by rotation and can lead to traumatic brain injury. To quantify brain injury risk based on measurements of kinematics on the head, finite element (FE) models and various brain injury criteria based on different factors of these kinematics have been developed, but the contribution of different kinematic factors has not been comprehensively analyzed across different types of head impacts in a data-driven manner. To better design brain injury criteria, the predictive power of rotational kinematics factors, which are different in (1) the derivative order (angular velocity, angular acceleration, angular jerk), (2) the direction and (3) the power (e.g., square-rooted, squared, cubic) of the angular velocity, were analyzed based on different datasets including laboratory impacts, American football, mixed martial arts (MMA), NHTSA automobile crashworthiness tests and NASCAR crash events. Ordinary least squares regressions were built from kinematics factors to the 95% maximum principal strain (MPS95), and we compared zero-order correlation coefficients, structure coefficients, commonality analysis, and dominance analysis. The angular acceleration, the magnitude and the first power factors showed the highest predictive power for the majority of impacts including laboratory impacts, American football impacts, with few exceptions (angular velocity for MMA and NASCAR impacts). The predictive power of rotational kinematics about three directions (x: posterior-to-anterior, y: left-to-right, z: superior-to-inferior) of kinematics varied with different sports and types of head impacts.
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Identifying Factors Associated with Head Impact Kinematics and Brain Strain in High School American Football via Instrumented Mouthguards. Ann Biomed Eng 2021; 49:2814-2826. [PMID: 34549342 PMCID: PMC8906650 DOI: 10.1007/s10439-021-02853-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/13/2021] [Indexed: 01/04/2023]
Abstract
Repeated head impact exposure and concussions are common in American football. Identifying the factors associated with high magnitude impacts aids in informing sport policy changes, improvements to protective equipment, and better understanding of the brain's response to mechanical loading. Recently, the Stanford Instrumented Mouthguard (MiG2.0) has seen several improvements in its accuracy in measuring head kinematics and its ability to correctly differentiate between true head impact events and false positives. Using this device, the present study sought to identify factors (e.g., player position, helmet model, direction of head acceleration, etc.) that are associated with head impact kinematics and brain strain in high school American football athletes. 116 athletes were monitored over a total of 888 athlete exposures. 602 total impacts were captured and verified by the MiG2.0's validated impact detection algorithm. Peak values of linear acceleration, angular velocity, and angular acceleration were obtained from the mouthguard kinematics. The kinematics were also entered into a previously developed finite element model of the human brain to compute the 95th percentile maximum principal strain. Overall, impacts were (mean ± SD) 34.0 ± 24.3 g for peak linear acceleration, 22.2 ± 15.4 rad/s for peak angular velocity, 2979.4 ± 3030.4 rad/s2 for peak angular acceleration, and 0.262 ± 0.241 for 95th percentile maximum principal strain. Statistical analyses revealed that impacts resulting in Forward head accelerations had higher magnitudes of peak kinematics and brain strain than Lateral or Rearward impacts and that athletes in skill positions sustained impacts of greater magnitude than athletes in line positions. 95th percentile maximum principal strain was significantly lower in the observed cohort of high school football athletes than previous reports of collegiate football athletes. No differences in impact magnitude were observed in athletes with or without previous concussion history, in athletes wearing different helmet models, or in junior varsity or varsity athletes. This study presents novel information on head acceleration events and their resulting brain strain in high school American football from our advanced, validated method of measuring head kinematics via instrumented mouthguard technology.
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Liu Y, Domel AG, Cecchi NJ, Rice E, Callan AA, Raymond SJ, Zhou Z, Zhan X, Li Y, Zeineh MM, Grant GA, Camarillo DB. Time Window of Head Impact Kinematics Measurement for Calculation of Brain Strain and Strain Rate in American Football. Ann Biomed Eng 2021; 49:2791-2804. [PMID: 34231091 DOI: 10.1007/s10439-021-02821-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/22/2021] [Indexed: 01/04/2023]
Abstract
Wearable devices have been shown to effectively measure the head's movement during impacts in sports like American football. When a head impact occurs, the device is triggered to collect and save the kinematic measurements during a predefined time window. Then, based on the collected kinematics, finite element (FE) head models can calculate brain strain and strain rate, which are used to evaluate the risk of mild traumatic brain injury. To find a time window that can provide a sufficient duration of kinematics for FE analysis, we investigated 118 on-field video-confirmed football head impacts collected by the Stanford Instrumented Mouthguard. The simulation results based on the kinematics truncated to a shorter time window were compared with the original to determine the minimum time window needed for football. Because the individual differences in brain geometry influence these calculations, we included six representative brain geometries and found that larger brains need a longer time window of kinematics for accurate calculation. Among the different sizes of brains, a pre-trigger time of 40 ms and a post-trigger time of 70 ms were found to yield calculations of brain strain and strain rate that were not significantly different from calculations using the original 200 ms time window recorded by the mouthguard. Therefore, approximately 110 ms is recommended for complete modeling of impacts for football.
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Affiliation(s)
- Yuzhe Liu
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.
| | - August G Domel
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Nicholas J Cecchi
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Eli Rice
- Stanford Center for Clinical Research, Stanford University, Stanford, CA, 94305, USA
| | - Ashlyn A Callan
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Samuel J Raymond
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Zhou Zhou
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Xianghao Zhan
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Yiheng Li
- Department of Biomedical Informatics, Stanford University, Stanford, CA, 94305, USA
| | - Michael M Zeineh
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Gerald A Grant
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
- Department of Neurology, Stanford University, Stanford, CA, 94305, USA
| | - David B Camarillo
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
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