Diagnostic Value Of Multimodal Magnetic Resonance For Diffuse Axonal Injury

Objective: to analyze the diffusion tensor imaging(DTI),glutamate chemical exchange saturation transfer(glucest)and magnetic resonance spectrum imaging(MRS)of diffuse axonal injury by multimodal magnetic resonance.to study the evolution of brain microstructure and glutamate concentration after early diffuse axonal injury,and to explore DTI,Glucest,MRS clinical application value of magnetic resonance imaging techniques in the diffuse axonal injury(DAI).Methods: the subjects of this study were DAI group and normal control group,the normal control group consisted of 20 normal adult male volunteers,and the DAI group consisted of 60 patients with early diffuse axonal injury that met the diagnostic criteria of diffuse axonal injury.In this experiment,conventional MRI,DTI,Glu CEST and MRS scans were performed on the normal control group and DAI group by magnetic resonance imaging technology.Results: Comparison of multimodal magnetic resonance imaging between early DAI group and control group : 1.DTI: the MD values of DAI group were statistically significant in corpus callosum(0.727±0.363),thalamus(0.942±0.269)and hippocampus(0.952±0.396)compared with the control group(P < 0.05).FA value in the early DAI group was in corpus callosum(0.67±0.057),and the difference was statistically significant compared with the control group(P < 0.05).FA values in the thalamus(0.304±0.047)and hippocampus(0.191±0.04)in the early DAI group were not significantly different from those in the control group(P > 0.05).2.Glucest:diffuse signal increase in brain parenchyma at scanning level can be seen in glucest diagram of Dai.The Glu CEST values of DAI group were in corpus callosum(19.768±2.258),hippocampus(21.353±2.062)and thalamus(22.044±2.009),with statistically significant differences compared with the control group(P < 0.001),and a slight CEST peak was observed around the resonance frequency of 2.9ppm in diffuse axonal injury group.3.Glucest and MRS: Glu and Glx concentrations in MRS in DAI group were increased,and the changes of Glu and Glx values were statistically significant(P < 0.05).There was a moderate positive correlation between Glu concentration in hippocampus and Glu CEST value in normal control group and DAI group(R=0.37,P < 0.01),and a strong positive correlation between Glx concentration and Glu CEST value(R=0.75,P < 0.001).Conclusion: 1.In the DAI group,DTI imaging showed that FA value decreased and MD value increased significantly,which reflected the pathophysiological changes caused by damage of integrity of nerve fiber bundle and change of nerve fiber bundle direction,cerebral edema leading to cerebral nerve fiber bundle edema,and damage of axonal structure leading to limited diffusion after early brain injury.MD value has higher sensitivity than FA value in detecting the changes of brain gray matter structure.2.Glucest brain glutamate concentration distribution map shows that diffuse axonal injury can lead to the increase of glutamate concentration in brain tissue.Glucest value in hippocampus is positively correlated with Glu and GLX of MRS,indicating that glucest value can more directly reflect the changes of glutamate after diffuse axonal injury than MRS.3.Combined with DTI,Glucest and MRS multimodal magnetic resonance imaging technology,it can provide some help for the early accurate diagnosis,treatment and prognosis of diffuse axonal injury.