Diffusion Tensor Imaging Using 3.0T MR Scanner In Rat C6 Glioma Model And The Correlative Study Of FA Value In Infiltrated Peritumoral Edema Tissue And AQP1

Part I:The establishment of Wistar rat C6 brain glioma modelObjective:To establish the stable and reliable late stage Wistar rat C6 brain glioma model.Materials and Methods:1.Rat C6 glioma cell lines were propagated in RPMI-1640 medium,supplemented with 10% fetal bovine serum,1% Penicillin-Streptomycin Solution,and were cultured with 5%C02 at 37℃in incubator. The tumor cells were maintained in continuous monolayer cell cultures in coming tissue culture flasks.Tumor cells were collected during logarithmic phase to count and detect cell activity.The concentrati-on were adjusted with complete medium.2.22 Wistar rats were divided into experimental group of 17 and control group of 5 by the random number table.The concentration of more than 1.0×106/10ul glioma cells and complete medium were injected stereotactically into the right caudate nucleus of the experimental group and control group, respectively.3. MRI scans and pathological observations were performed about 3～4 weeks after implantation for the rats.Results:1. One of the experimental group died after about lh,and another died of unknown causes 15 days afterr implantation (the pathology demonstrated tumor formation), the other 15 rats were confirmed the tumor formation by the subsequent MRI and pathological 硕士学位论文英文摘要examination.The control group of 5 were alive, and no tumor formation. 2. There is peritumor edema and/or tumor cell invasion about 3～4 weeks after implantation by Postoperative MRI and pathological examination.Conclusion:Wistar rat C6 glioma model is a stable and reliable model, After implantation,tumor grows rapidly,and the success rate is very high.The model can meet experimental requirements for the peritumoral edema and/or tumor infiltration about 3 to 4 weeks after inoculation.PartⅡ:The study of diffusion tensor imaging using 3.0T MR scanner in rat C6 brain glioma model in vivoObjective:To study the average fractional anisotropy(FA) and mean diffusivity (MD) values in the wistar rat C6 brain glioma regions and the contralateral normal brain parenchyma using 3.0T Magnetic resonance scanner,and compare the two different selective methods of region of interest (ROI).Materials and Methods:22 Wistar rats were divided into experim-ental group of 17 and control group of 5 by the random number table. The concentration of more than 1.0×106/10ul glioma cells and complete medium were stereotactically injected into the right caudate nucleus of the experimental group and controlgroup,respectively.Conventional MRI,DTI,enhanced T1WI and SAG T1-3D-bravo scans were performed using the GE Signa HDx 3.0T MRI scanner with the rat special coil about 3～4 weeks after implantation.And glioma and peritumoral edema were distin-guished by T2WI,FLAIR,enhanced T1WI and SAG T1-3D-bravo scans.Postproeessing was done by the DTI specific softw-are Function Tool to gain FA and MD images. ROIs were drawn,avoiding hemorrhage and necrosis areas, in different selective methods (3 equal-sized ROIs and a single larger ROI) in tumor parenchyma and the contralateral normal brain parenchyma.Results:The average FA values of 3 equal-sized ROIs in the 15 wistar rats C6 brain glioma regions and the contralateral normal brain parenchyma were (0.1075±0.02) and (0.312±0.024), respectively;the average MD values were (0.944±0.029)×10-3mm2/s and (0.808±0.036)×10-3mm2/s, respectively.Two independent-sample T test of the two groups showed statistically significant difference (P<0.05).The average FA values of single larger ROI in the wistar rat C6 brain glioma regions and the contralateral normal brain parenchyma were (0.118±0.039) and (0.310±0.052),respectively; the average MD values were(0.941±0.047)×10-3 mm2/s and (0.806±0.043)×10-3 mm2/s,respectively.Two independ-ent-sample T test of the two groups also showed statistically significant difference (P<0.05). Paired-sample T test of obtained FA values by the two different measurement methods showed statistically significant difference(P<0.05),while no statistical significance between the MD values (P> 0.05).Conclusion:It is feasible to perform DTI scan in the rat C6 brain glioma model using a clinical 3.0T MR scanner,and the FA and MD values measured in the rat C6 brain glioma regions and the contralateral normal brain parenchyma can be used for reference in future studies. Methodologically, the study showed the two different selective methods of region of interest could influence the measurements of FA vales, while have no effect on the measurements of MD values.Part III:The correlative study of AQP1 expression in rat brain glioma infiltrated peritumoral edema tissue and the FA valueObjective:Magnetic resonance diffusion tensor imaging (MR-DTI) was performed in Wistar rat brain glioma infiltrated peritumoral edema tissue to analyze its features, and explore the correlation of AQP1 expression in rat brain glioma infiltrated peritumoral edema tissue by immunohistochemical findings and the FA value.Materials and Methods:22 Wistar rats were divided into experimental group of 17 and control group of 5 by the random number table.The concentration of more than 1.0×106/10ul glioma cells and complete medium were injected stereotactically into the right caudate nucleus of the experimental group and control group,respectively. Conv-entional MRI, DTI, enhanced T1WI and SAG T1-3D-bravo scans were performed using the GE Signa HDx 3.0T MRI scanner with the rat special coil about 3-4 weeks after implantation. And gliomas and peritumoral edema were distinguished by T2WI,FLAIR,enhanced T1WI and SAG T1-3D-bravo scans.Postproeessing was done using the DTI specific software Function Tool to gain FA images. ROIs were drawn, av-oiding hemorrhage and necrosis areas, in 3 equal-sized (2mm2,9pix). ROIs in peritumoral edema and the contralateral normal brain parenchy-ma to gain FA values. Let the contralateral normal brain tissue as an internal control. The whole rat brain was fixed by 4% paraformaldehyde perfusion after MRI scans immediately, and then the rats were sacrificed to take the whole brain fixed by excess of 1% sodium pentobarbital. Peritumoral brain edema tissue corresponding the maximum level of the tumor were selected to do continuous coronal sections. Each rat brain was examined histologically using HE and immunohistochemical staining for AQP1. Pearson correlation analysis was used to determine the relations between FA values and the IOD value of AQP1 expression.Correlation coefficient was also calculated and T test was made with statistical significance when P<0.05. Results:The average FA values of 3 equal-sized ROIs in the 15 rats C6 brain glioma peritumoral edema tissue about 3～4 weeks after implantation were (0.204±0.036). The results were lower than the average FA values (0.310±0.027) of the contralateral normal brain tissue. Two independent-sample T test of two groups showed statistically significant difference (P<0.05).Correlation were Negative between FA values of infiltrated peritumoral edema tissue and the IOD value of AQP1 expression(r=-0.81,P<0.05).Conclusion:The correlation of AQP1 expression in rat brain glioma infiltrated peritumoral edema tissue and the FA value were negative.with the increase of AQP1 expression level, FA value decreased.