Early stage of diffusional kurtosis imaging and dynamic contrast-enhanced magnetic resonance imaging correlated with long-term neurocognitive function after experimental traumatic brain injury.

Development of a reliable biomarker for prognostic monitoring of cognitive impairment after traumatic brain injury (TBI) is of great importance. The aim of the study was to explore the value of early diffusional kurtosis imaging (DKI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in evaluation of chronic cognitive function after TBI. MRI was performed on TBI and control rats at 7 days post-injury. MRI parameters were measured in bilateral cortex, hippocampus, thalamus and corpus callosum (CC). All the rats underwent Morris water maze (MWM) at 6 months after injury. Immunohistochemistry (IHC) analysis of neuron [NeuN], astroglia [GFAP], microglia [Iba-1], and myelin [MBP] was performed after the MWM test. Our study revealed that, TBI group showed higher volume transfer coefficient (Ktrans) value in ipsilateral cortex (P < 0.0001) and no detectable changes in other regions-of-interest (ROIs), compared with control group. DKI showed higher MK in all ipsilateral ROIs (P < 0.05), higher MD in ipsilateral cortex, hippocampus and CC (P < 0.05 for all) in TBI group. TBI group had worse performance in MWM test at 6 months post-injury(P < 0.05). IHC analysis showed lower NeuN, and higher GFAP and Iba-1 in all ipsilateral ROIs (P < 0.05) in TBI rats. NeuN, and GFAP and Iba-1 correlated significantly with MK value in ipsilateral regions of cortex. The MK value of ipsilateral cortex and CC and Ktrans value of ipsilateral cortex also correlated significantly with time in the target quadrant. Therefore, our study indicated that early DKI and DCE-MRI could be used to assess the microstructural changes associated with long-term cognitive outcome following TBI.