In contact sports, it is common to see frequent head injuries or indeed traumatic brain injuries (TBI) from minor impacts which anecdotally appear increased as a result of concussion. There is little agreement in the literature regarding the change in CSF volume as a function of dehydration. Here we measure the volume using TrueFISP at 1.5T (Avanto, Siemens, DE) and thresholding images to determine the number of CSF voxels. Imaging reveals a decrease in CSF owing to dehydration. New rehydration regimens should allow for reduction in TBI incidence.