Real-time, whole-brain, temporally resolved pressure responses in translational head impact

Theoretical debate still exists on the role of linear acceleration (a(lin)) on the risk of brain injury. Recent injury metrics only consider head rotational acceleration (a(rot)) but not a(lin), despite that real-world on-field head impacts suggesting alin significantly improves a concussion risk function. These controversial findings suggest a practical challenge in integrating theory and real-world experiment. Focusing on tissue-level mechanical responses estimated from finite-element (FE) models of the human head, rather than impact kinematics alone, may help address this debate. However, the substantial computational cost incurred (runtime and hardware) poses a significant barrier for their practical use. In this study, we established a real-time technique to estimate whole-brain a(lin)-induced pressures. Three hydrostatic atlas pressures corresponding to translational impacts (referred to as 'brain print') along the three major axes were pre-computed. For an arbitrary a(lin) profile at any instance in time, the atlas pressures were linearly scaled and then superimposed to estimate whole-brain responses. Using 12 publically available, independently measured or reconstructed real-world a(lin) profiles representative of a range of impact/injury scenarios, the technique was successfully validated (except for one case with an extremely short impulse of approx. 1 ms). The computational cost to estimate whole-brain pressure responses for an entire a(lin) profile was less than 0.1 s on a laptop versus typically hours on a high-end multicore computer. These findings suggest the potential of the simple, yet effective technique to enable future studies to focus on tissue-level brain responses, rather than solely relying on global head impact kinematics that have plagued early and contemporary brain injury research to date.