ADC mapping and T1-weighted signal changes on post-injury MRI predict seizure susceptibility after experimental traumatic brain injury

Abstract

Objective: Post-traumatic epilepsy (PTE) is a serious complication of traumatic brain injury (TBI). This study is designed to determine the feasibility of using multiparametric MRI endpoints to predict differences in seizure susceptibility after experimental TBI.

Methods: MRI imaging and behavioral measurements were performed at multiple time points after lateral fluid percussion injury (FPI) in rats. Seizure susceptibility was determined by video-electroencephalogram (EEG) monitoring and off-line signal analysis after chemoconvulsant challenge.

Results: Multiple MRI endpoints, including measures of injury-related brain swelling (normalized interhemispheric volume difference, NIVD) and T1-weighted signal change with contrast enhancement (a measure of blood–brain barrier disruption, BBBD), reliably distinguished between injured and sham-injured animals at 72 hours after injury. ADC (apparent diffusion coefficient) values (a measure of water diffusivity) in injured cortex at 72 hours and 1 week after injury, BBBD in injured cortex at 72 hours after injury and NIVD at 72 hours after injury were significantly correlated with EEG-based measures of seizure susceptibility to chemoconvulsant challenge at 3 months after injury.

Conclusions: The correlations between our MRI quantitative endpoints and EEG-based measures of seizure susceptibility to chemoconvulsant challenge in injured animals versus sham-injured animals support the feasibility of these MRI endpoints as potential biomarkers for post-traumatic epileptogenesis.

Keywords:

• Epileptogenesis
• Fluid percussion injury
• Kainate
• MRI
• Post-traumatic epilepsy

The authors wish to thank the Colorado Injury Control and Research Center for funding support for this project. The authors also wish to thank Archana Shrestha, MD, and Amy Brooks-Kayal, MD, for their invaluable editing assistance. Funding for this project was provided by the CDC and the Colorado Injury Control and Research Center. The Animal Imaging Core is supported through the Animal Imaging Shared Resources Core by the NCI P30 Cancer Center Grant (CA046934) and CTSA award (UL 1RR025780).