Reduced myelination has been observed in rodents and humans after mild traumatic brain injury (mTBI). However, conventional MR imaging sequences cannot directly detect any signal from myelin. In this study, we aimed to evaluate a 3D IR-UTE sequence for selective imaging of myelin in mice using a standard controlled cortical impact (CCI) model of mTBI with histological confirmation. To demonstrate the clinical feasibility, a translational 3D IR-UTE technique was developed and applied to healthy volunteers and mTBI patients at 3T. The preliminary results demonstrate the feasibility of volumetric myelin mapping using the 3D IR-UTE sequences at 7T and 3T.