Biomedical sciences instrumentation
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Diffusion tensor imaging (DTI) has been successfully used to image the human brain and spinal cord, although there is still controversy as to which tensor-derived diffusion indices produce the greatest contrast and provide the best anatomical representation of gray and white matter within the spinal cord. The aim of this study was to determine the best diffusion indices for use in the spinal cord using the detectability index, ROC analysis, and opinion data in the form of a survey. DTI of the entire spinal cord (C1-L1) was performed on five neurologically intact human subjects at 1.5-T. ⋯ The survey indicated that the deviation of the primary eigenvalue with respect to mean diffusivity (MA1) was significantly better than all other indices at representing underlying spinal cord morphology. This is consistent with previous results showing lack of detail in ventral gray matter regions using the FA. Results indicate FA and MA1 provide the highest contrast and most accurate representation of underlying morphology, respectively.
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Longitudinal barriers, such as guardrails, are designed to prevent a vehicle that leaves the roadway from impacting a more dangerous object while minimizing risk of injury to the vehicle occupants. Current full-scale test procedures for these devices do not consider the effect of occupant restraints such as seat belts and airbags. The purpose of this study was to determine the extent to which restraints are used or deployed in longitudinal barrier collisions and their subsequent effect on occupant injury in these collisions. ⋯ Seat belt usage rates were approximately 60 and 80 percent for non-airbag-equipped and airbag-equipped vehicles, respectively. Compared to fully restrained occupants, relative risk of injury for no airbag/belted, airbag/unbelted, and no airbag/unbelted occupants was 1.6, 7, and 11.7, respectively. Despite these large differences in relative risk, however, 95 percent of the occupants in the analyzed data were either uninjured or sustained minor injury, which reinforces the overall effectiveness of these roadside devices.
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Commonly considered a continuum of injuries, diffuse brain injury (DBI) ranges from mild concussion to severe diffuse axonal injury. The lower end of the spectrum is generally referred to as mild traumatic brain injury (MTBI). More severe forms of DBI have garnered extensive experimentation while these milder cases are considerably less explored. ⋯ Prior experimentation estimated an angular acceleration of approximately 350 krad/s2 is necessary for the induction of mild traumatic brain injury (MTBI) in the rodent. To induce these magnitudes of angular acceleration in a repeatable manner, the impacting interface must be critically analyzed. This investigation uses a mathematical model based on parameters of a previously developed experimental model to assess the impacting interface such that angular accelerations are sufficient to produce MTBI in the rodent.
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Translational and rotational accelerations from blunt head impact can induce excessive brain strain and cause traumatic brain injuries. However, it is not clear which acceleration plays a major role in the mechanism. ⋯ Results indicated that rotational acceleration contributes more than 90% of total strain, and translational acceleration produces minimal strain. Therefore, the rotational component is a more important biomechanical metric in this study.
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Facial bone fractures in the military can result from direct loading of night vision goggles on the orbital region. Facial fracture research has shown that increasing the area over which the load is applied increases the load tolerance. The purpose of this study is to apply this concept to reducing the risk of facial bone fracture from night vision goggle impacts. ⋯ Two impacts to the male subject with a custom face shield resulted in peak loads of 4554 N and 5101 N with no injury. The final impact to the male subject had a peak load of 2010 N with complete orbital fracture due to the absence of a countermeasure. From these tests it is shown that facial fracture risk from night vision goggle impact can be reduced using a contoured rigid face shield.