Principal components of brain deformation in response to skull acceleration: The roles of sliding and tethering between the brain and skull

The relationship between skull acceleration and brain injury is not well understood, in large part because of the challenge of visualizing the brain's mechanical response in vivo. This difficulty also complicates the validation of computational mechanics predictions. Our dynamic magnetic resonance (MR) imaging suggests an important role for the attachments between brain and skull. Here, we present an MRI-based method for identifying the dominant modes of brain displacement relative to the skull during angular acceleration of the head, and apply it to study brain/skull interactions in live volunteers. The approach was to estimate dynamic intracranial displacement fields from a sequence of tagged MR images of the brain and skull, then identify dominant displacement modes using principal component (PC) analysis. After verifying the method through analysis of a simulated 2-D vibrating plate and MR images of a cylindrical gel phantom, the method was applied to show that the dominant mode of brain/skull interaction is one of sliding arrested by brain/skull meninges in a few specific regions.