The spinal cord undergoes physical deformation during traumatic spinal cord injury (TSCI), which results in biological damage. This study demonstrates a novel approach, using magnetic resonance imaging and image registration techniques, to quantify the three-dimensional deformation of the cervical spinal cord in an in vivo rat model. Twenty-four male rats were subjected to one of two clinically relevant mechanisms of TSCI (i.e. contusion and dislocation) inside of a MR scanner using a novel apparatus, enabling imaging of the deformed spinal cords. The displacement fields demonstrated qualitative differences between injury mechanisms. Three-dimensional Lagrangian strain fields were calculated, and the results from the contusion injury mechanism were deemed most reliable. Strain field error was assessed using a Monte Carlo approach, which showed that simulated normal strain error experienced a bias, whereas shear strain error did not. In contusion injury, a large region of dorso-ventral compressive strain was observed under the impactor which extended into the ventral region of the spinal cord. High tensile lateral strains under the impactor and compressive lateral strains in the lateral white matter were also observed in contusion. The ability to directly observe and quantify in vivo spinal cord deformation informs our knowledge of the mechanics of TSCI.
Keywords: Biomechanics; Clinical injury mechanism; Image registration; In vivo; MRI; Rodent model; Strain field; Traumatic spinal cord injury.