Cognitive impairment and white matter degeneration are common in hemodialysis patients. Hemodialysis can severely impede blood flow and create osmotic imbalances in the brain. This may cause brain injury by a mechanism similar to that of stroke. To investigate the acute effects of hemodialysis on the brain, we used a novel system to perform diffusion and T1 weighted MRI scans during hemodialysis. Several tracts exhibit diffusion tensor imaging markers for cytotoxic and ionic edema. Increased white and grey matter volume during hemodialysis further support the presence of ionic edema. Ionic and cytotoxic edema are evidence of acute brain injury.