Age- and sex-related effects in children with mild traumatic brain injury on diffusion magnetic resonance imaging properties: A comparison of voxelwise and tractography methods

Although there are several techniques to analyze diffusion-weighted imaging, any technique must be sufficiently sensitive to detect clinical abnormalities. This is especially critical in disorders like mild traumatic brain injury (mTBI), where pathology is likely to be subtle. mTBI represents a major public health concern, especially for youth under 15 years of age. However, the developmental period from birth to 18 years is also a time of tremendous brain changes. Therefore, it is important to establish the degree of age-and sex-related differences. Participants were children aged 8-15 years with mTBI or mild orthopedic injuries. Imaging was obtained within 10 days of injury. We performed tract-based spatial statistics (TBSS), deterministic tractography using Automated Fiber Quantification (AFQ), and probabilistic tractography using TRACULA (TRActs Constrained by UnderLying Anatomy) to evaluate whether any method provided improved sensitivity at identifying group, developmental, and/or sex-related differences. Although there were no group differences from any of the three analyses, many of the tracts, but not all, revealed increases of fractional anisotropy and decreases of axial, radial, and mean diffusivity with age. TBSS analyses resulted in age-related changes across all white matter tracts. AFQ and TRACULA revealed age-related changes within the corpus callosum, cingulum cingulate, corticospinal tract, inferior and superior longitudinal fasciculus, and uncinate fasciculus. The results are in many ways consistent across all three methods. However, results from the tractography methods provided improved sensitivity and better tract-specific results for identifying developmental and sex-related differences within the brain.