Investigating white matter injury after mild traumatic brain injury

Purpose of review Traumatic brain injury (TBI) often results in traumatic axonal injury (TAI). This is difficult to identify using conventional neuroimaging methods. We review recent work that uses advanced imaging methods to identify TAI following mild (m)TBI. Recent findings Susceptibility-weighted imaging (SWI) is a highly sensitive way of identifying microbleeds, which are a marker of TAI. Diffusion tensor imaging (DTI) provides a more flexible way of investigating white matter injury. Recent studies largely confirm that DTI is sensitive to white matter damage after mTBI. Distinct DTI abnormalities are observed in the acute and subacute/chronic stages. DTI measurements change dynamically after an injury, reflecting the evolving pathological processes. DTI abnormalities correlate with cognitive and neuropsychiatric impairments. Importantly, DTI can contribute to the prediction of clinical outcome and has begun to be applied to the study of sports and blast injury. Summary DTI and SWI are important advances in MRI that allow more detailed investigation of white matter injury. SWI is a highly sensitive way of identifying microbleeds. DTI is a flexible way of quantifying white matter integrity, and provides a method of diagnosing clinically significant white matter injury when conventional imaging is normal.