The Evaluation Of The Peritumoral Edema Area Of The Rat C6 Brain Glioma Model By Diffusion Tensor Imaging

Part I:Establishment of wistar rat C6 brain glioma modelObjective:To establish the easy,practical and stable rat C6 brain glioma model.Methods:22 wistar rats were divided into experimental group(n=17),control group(n=5).C6 cells were implanted into the right caudate nucleus of brain hemisphere of experimental group with stereotactic technique.The same concentration of complete medium were implanted into the control group.The growth behaviors of the brain tumor were observed at 1,2,3 weeks by MR after the implantation. After 3 weeks, the rats were killed after 4% paraformaldehyde perfusion and pathological examination and immunohistologic stain for human GFAP and S-100βwere used.Results:One of the experimental group died after about lh,and one of unknown reason 15days after implantation.All 15 rats were confirmed the tumor formation by the subsequent MRI and pathological examination.The establishment of models were successful.pathological histochemical examination demonstrated the tumor was glioma. Human S-100βand GFAP stain were positive.The growth rate of glioma model was 100%. The malignant degree of the tumors were over degree III.The control group of 5 were survive,and no tumor formation.Conclusion:1,the C6 brain glioma model is easy and rapid(2～3weeks),it has a good stability, excellent repetition and high success rate in wistar rats.2,After implantation,the best experimental time in the treatment of glioma maybe is 2 weeks around.There is peritumor edema invasion after 3 weeks which is the best time for the experiment of peritumor edema.PartⅡ:The evaluation of the cell infiltrating of the brain glioma model by diffusion tensor imagingObjective:To explore the evaluation of the cell infiltrating of the brain glioma model by diffusion tensor imaging.Methods:Conventional MRI,DTI,DTT,enhanced T1WI and SAG T1-3D-bravo scans were performed in 3 weeks after implantation for the 15 C6 brain glioma models using the GE Signa HDx 3.0T MRI scanner with the rat special coil.Distinguish the glioma and peritumoral edema.Postprocessing was done using a DTI specific software to gain FA images.ROIs were drawn in 3 equal-sized(2mm2,9pix)ROIs in peritumoral edema and the contralateral normal brain parenchyma.The whole rat brain was fixed by 4% paraformaldehyde perfusion after MRI scans immediately.The maximum level of the tumor corresponding peritumoral brain edema were selected to do continuous coronal sections,then stained with routine HE.The real cell infiltration level of peritumoral edema was gained Under the light microscope.Pearson regression software was used to determine the relations between FA values and the real cell infiltration level.Correlation coefficient was also calculated and t-test was made (with statistical significance when P<0.05).The relationship between the brain tumor and white matter fiber were analyzed simultaneously. Results:the 3 equal-sized ROIs average FA values in the 15 rats C6 brain glioma peritumoral edema were (0.204±0.036),the results were lower than average FA values (0.310±0.027) of the contralateral normal brain tissue.The results were statistically significant differences between the two groups(P<0.05).Correlation between FA values of infiltrated peritumoral edema tissue and the cell infiltration level were negative (r=-0.812),which is statistically significant (P<0.05).DTT demonstrated that the influences of space-occupying effect and infiltrating invasion of brain tumor and peritumoral edema on white matter fiber tracts could be displacement and destruction.Conclusion:1,Correlation between FA values of infiltrated peritumoral edema tissue and the cell infiltration level were negative.FA values in peritumoral area can be used to evaluate invasive potential of cerebral gliomas as a reference.2,Evaluating the relation -ship between brain tumor and white matter fiber tracts by DTI is helpful to design surgical approach.