In the May 23, 2013 issue of Brain Injury, David E. Ross, et al. submitted a Letter to the Editor entitled “Brain MRI volumetry in a single patient with mild traumatic brain injury.”  The report described the case of a 42 year old man who was in a motor vehicle accident in May 2008, leading to a mild traumatic brain injury and other injuries.  His MRI brain data were analyzed with Neuro Quant (a FDA‑approved computer‑automated method for measuring MRI brain volume) and susceptibility‑weighted imaging (SWI) to assess for signs of old bleeding.  A volumetric cross‑sectional (one point in time) analysis showed no brain atrophy, consistent with initial CT and MRI scans of the brain.  Volumetric longitudinal (2 points in time) analysis show progressive atrophy in several brain regions.  Dr. Ross reports that the case demonstrated that in a single patient the principle discovered in multiple previous group studies, namely that longitudinal design is more powerful than the cross‑sectional design for finding atrophy in patients with traumatic brain injury.