• Xiran Chen, Yanzi Chen, Yuan Xu, Qilu Gao, Zhiwei Shen, and Wenbin Zheng.
• Department of Radiology, Third Affiliated Hospital, Southern Medical University, Guangzhou, Guangdong, China.
• J Magn Reson Imaging. 2019 Apr 1; 49 (4): 1069-1077.

BackgroundDiffuse axonal injury (DAI) is one of the devastating types of traumatic brain injury, but is difficult to detect on conventional imaging in its early stages.PurposeTo test the technical feasibility and diagnostic value of diffusion kurtosis imaging (DKI) and glutamate chemical exchange saturation transfer (GluCEST) imaging in the brain after DAI.Study TypeProspective.Animal ModelSixty Sprague-Dawley rats. The DAI model was induced by using the impact acceleration model of Marmarou et al with modified settings.Field Strength/SequenceA 7.0T animal MR scanner with a fast spin-echo sequence (T2 -weighted imaging), fast spin-echo multislice sequence (DKI), echo planar imaging in the signal of the chemical exchange saturation transfer sequence (CEST), and point-resolved spectroscopy sequence (hydrogenproton magnetic resonance spectroscopy, 1 H-MRS).AssessmentBrain MRI scanned before and 2 hours after injury. DKI images were processed with MatLab and MRIcro software, GluCEST images were processed using software routines written in MatLab, and spectroscopic data were postprocessed with LCModel.Statistical TestsThe parameters of these techniques were assessed using the independent sample t-test and Pearson correlation.ResultsMean kurtosis and mean diffusivity values were significantly higher than controls in the parietal lobe, hippocampus, and thalamus (P <  0.01). However, fractional anisotropy was lower only in the parietal lobe, with no detectable changes in the hippocampus and thalamus. GluCEST values of the parietal lobe, hippocampus, and thalamus were significantly higher than controls in DAI rats (P <  0.01). This change was further validated through 1 H-MRS. A positive correlation was observed between glutamate (Glu) and glutamate compound (Glx) concentrations and GluCEST values (Glu: R2  = 0.589, Glx: R2  = 0.878).Data ConclusionDKI and GluCEST might be acceptably sensitive for tracking microstructural and neurochemical changes in the brain following DAI.Level Of Evidence1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1069-1077.© 2018 International Society for Magnetic Resonance in Medicine.

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