Longitudinal evaluation of white matter tracts post traumatic brain injury using a pediatric porcine model

BACKGROUND: Traumatic brain injury (TBI) induced white matter damage in the brain has a lasting impact on brain functions, leading to cognitive and motor impairments. NEW METHOD: To better predict patient deficits, develop treatment plans, and identify novel therapies, longitudinal effects of TBI on white matter tracts were evaluated using a pediatric porcine model. Diffusion-weighted MRI data from a cohort of female piglets (n = 22) consisting of three groups, including sham, mild- and severe-TBI pigs, was acquired at 4 time points (pre-TBI, 1D-, 63D-, and 119D-post TBI). A group of common white matter tracts was generated using a probabilistic independent component tractography approach. The tracts were evaluated, both laterally between two hemispheres and longitudinally among 4 time points, to measure changes in injured tracts over a 120-day period. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were calculated for these tracts and compared. RESULTS: 9 pairs of white matter tracts were generated, 7 of which corresponded to those found in adult pigs in the Porcine Neurological Imaging Space. Our results showed consistently lower FA and higher diffusivity in the ipsilateral hemisphere (with TBI injury) for all 9 pairs. Longitudinal changes in these metrics indicated a complex interplay between typical development and TBI recovery. COMPARISON WITH EXISTING METHODS: This method captured similar trends in FA and diffusivity as found in empirical data. CONCLUSION: The probabilistic IC tractography approach effectively characterized lateral and longitudinal changes to white matter tracts using a multi-group and multi-time-point pediatric porcine TBI model.