Deformation of the human brain was measured in tagged magnetic resonance images (MRI) obtained dynamically during angular acceleration of the head. This study was undertaken to provide quantitative experimental data to illuminate the mechanics of traumatic brain injury (TBI). Mild angular acceleration was imparted to the skull of a human volunteer inside an MR scanner, using a custom MR-compatible device to constrain motion. A grid of MR "tag" lines was applied to the MR images via spatial modulation of magnetization (SPAMM) in a fast gradient echo imaging sequence. Images of the moving brain were obtained dynamically by synchronizing the imaging process with the motion of the head. Deformation of the brain was characterized quantitatively via Lagrangian strain. Consistent patterns of radial-circumferential shear strain occur in the brain, similar to those observed in models of a viscoelastic gel cylinder subjected to angular acceleration. Strain fields in the brain, however, are clearly mediated by the effects of heterogeneity, divisions between regions of the brain (such as the central fissure and central sulcus) and the brain's tethering and suspension system, including the dura mater, falx cerebri, and tentorium membranes.

Shear strain patterns in a cylindrical gelatin sample under transient angular acceleration were measured by tagged magnetic resonance imaging (MRI). Measured strain fields were compared to theoretical strain fields obtained by finite element (FE) simulation. Agreement between theory and experiment is very good. The current results support the utility of the experimental approach for tasks such as measurement of shear waves in brain tissue during angular acceleration of the skull. The results also show that a simple viscoelastic model is suitable to describe rapid shear deformation of a gel biomaterial.

Deformation of the human brain was measured in tagged magnetic resonance images (MRI) obtained dynamically during angular acceleration of the skull. This study was undertaken to provide much needed experimental data for the quantitative study of traumatic brain injury (TBI). A custom device was made to impart mild angular acceleration to the skull of a human volunteer inside an MR scanner. Images with a superimposed grid of “tag” lines were obtained using spatial modulation of magnetization (SPAMM) in a fast gradient-echo imaging sequence. Images of the moving brain were obtained dynamically by synchronizing the imaging process with the motion of the head. The deformation of the brain was characterized quantitatively with Lagrangian strain. Strain fields showed reduced strain along the central fissure and to a lesser degree, the central sulcus, suggesting that divisions between regions of the brain may serve to mechanically isolate these regions. Results emphasize the critical role of the brain’s suspension, including the dura mater, falx cerebri, and tentorium membranes, in modulating its deformation.

A magnetic resonance (MR) method for measuring the deformation of the brain during angular acceleration was validated in a simple model system. Experimentally-derived shear strain patterns in a cylindrical gel “phantom” under angular acceleration were compared to analogous strain fields predicted by finite element simulation.