The investigators are partnering with an ongoing pediatric TBI trial (ADAPT Trial: Approaches and Decisions in Acute Pediatric TBI) and will also be enrolling past UW patients and healthy controls. Consistency in timing of follow-up scans, large sample size and access to the ADAPT Trial injury severity data and neuropsychological testing will give this study unprecedented power to assess the relationship between early MRI findings and subsequent atrophy, white matter injury, network connectivity changes and neurocognitive and behavioral impairments.