MRI detects macro- and microstructural changes to normal brain tissue following hemi-brain radiotherapy

Approximately 50-90% of patients that survive treatment for brain tumours experience dementia-like cognitive impairments. Here we use MRI and behavioural testing to assess longitudinal changes to brain macro- and microstructure and cognitive dysfunction following hemi-brain radiotherapy. We show shrinkage of cortical and hippocampal regions in the irradiated hemisphere, and expansion of cortical tissue in the non-irradiated hemisphere relative to non-irradiated control mice. Brain microstructure was also changed including increases in gray matter diffusivity, and decreases in white matter fractional anisotropy. Changes on MRI were accompanied by early and persistent deficits in novel object recognition.