The Dartmouth Head Injury Model (DHIM)
The biomechanical mechanisms behind traumatic brain injury
(TBI) have been an active research focus for more than 70 years. However,
the field is still largely focused on impact kinematics or estimated brain
responses in generic regions from single head impact to predict a binary
brain injury status on a population basis. A much more graded injury characterization,
both spatially and temporally, is needed especially for mild TBI (mTBI)
including sports concussion. There is a pressing need to study the distribution
of injury from cumulative impacts, to correlate with brain functional
alteration or recovery, and to investigate on an individual basis.
This work builds on top of the Dartmouth Head Injury Model (DHIM). This is a subject-specific finite element model of the human head created from high-resolution MRI of an actual athlete (Ji et al., 2015). It also allows the creation of other subject-specific head models via image registration. The DHIM has a high mesh quality and geometrical accuracy, based on quantitative measures. The model was successfully validated against relative brain-skull displacement and pressure responses from cadaveric impacts as well as strain responses from a live human volunteer, with performance rated as "good" to "excellent" according to an established fidelity rating (Ji et al., 2015, 2014; Zhao et al., 2015).
We are sharing with the research community our pre-computed brain strain response atlas (Ji and Zhao, 2015; Zhao and Ji, 2015b) as well as the brain pressure response atlas (Zhao and Ji, 2016) for research use and evaluation, along with the associated analysis software. We are open to any constructive suggestions, recommendations, and comments to improve our work further.
The original pcBRA-strain encodes the peak maximum principal strain at every element, which requires an explicit definition of the element structure. To facilitate the exchange of data and results, the pcBRA-strain was spatially resampled to generate a set of 3D grid data points encoded with strain values, analogous to stacked medical images such as MRI or CT. This allows direct application of many existing visualization and analysis routines, without the need for element definition.
Here is the data (right click to save, may need to rename to ".mat" extension) and demo program in Matlab, which describes how to generate the following "happy" and "neutral" faces (they were created by overlaying two symmetric strain maps on an axial image plane in "occipital" and "frontal" impacts, respectively. The given subset of data only supports the "neutral" face on the right.
The three pre-computed pressure responses are shown below. They are linearly superimposed to obtain whole-brain pressure in an arbitrary translational head impact. Here is the data (right click to save, may need to rename to ".mat" extension) and demo program in Matlab.
Copyright 2015, The Trustees of Dartmouth College. Permission to use for Research Purposes Only. All Other Rights Reserved.