Comparing imaging biomarkers of cerebral edema after TBI in young adult male and female rats

[Display omitted] •Cerebral edema is a critical element of TBI patholophysiology that can be assessed with quantitative T2 or diffusion-weighted MRI.•Both male and female rats had increased T2 in the injured cortex 24 h after CCI.•ADC calculated from diffusion-weighted MRI was variable and did not show significant injury effects at 24 h.•Male rats had increased brain water content compared with shams, females did not.•Imaging biomarkers of edema were correlated with brain water content in males but not in females. Traumatic brain injury (TBI) is one of the leading causes of death and disability worldwide. Cerebral edema following TBI is known to play a critical role in injury severity and prognosis. In the current study we used multimodal magnetic resonance imaging (MRI) to assess cerebral edema 24 h after unilateral contusive TBI in male and female rats. We then directly quantified brain water content in the same subjectsex vivo.We found that both males and females had similarly elevated T2 values after TBI compared with sham controls. Apparent diffusion coefficient (ADC) was more variable than T2 and did not show significant injury effects in males or females. Brain water was elevated in male TBI rats compared with sham controls, but there was no difference between female TBI and sham groups. Notably, MRI biomarkers of edema were more closely correlated with brain water in male rats; female rats did not show any relationship between brain water and T2 or ADC. These observations raise questions about the interpretation of radiological findings traditionally interpreted as edema in female TBI patients. A better understanding of sex differences and similarities in the pathophysiology of post-traumatic edema is needed to help improve patient management and the development of effective treatment strategies for men and women.