| Part I The application of 3.0T magnetic resonance diffusion tensor imaging for rat C6 glioma gradingObjective:To explore the value of fractional anisotropy(FA)of magnetic resonance diffusion tensor imaging(DTI)parameters for rat glioma grading and the effect of Gd-DTPA on the evaluation of FA in late-stage rat glioma.Materials and Methods:75 adult Wistar rats were randomly divided into experimental aroup A and control group B according to a random number table.Group A was inoculated C6 glioma cells on the right caudate nucleus by brain stereotactic device.All surviving experimental Wistar rats received conventional 3.0T MRI.DTI and T1WI enhanced scans at 1?2 weeks and 3?4 weeks,which received DTI again after the contrast agent was injected.FA value o tumor and contralateral brain tissue were obtained by taking average value of region of interest(ROI).Compare the difference of A value between low-grade gliomas and high-grade gliomas,analyze the efficacy of FA value in glioma stagintg diagnosis by ROC curve and explore the difference of FA value before and ater injection of contrast agent.P<0.05 was considered statistically significant.Results:(1)The FA value of high grade C6 glioma was higher than low grade glioma,the difference was statistically significant(P<0.05).Meanwhile,the area under the ROC curve of FA value for C6 glioma grading was 0.778,showing significantly difference(P<0.05).(2)The FA value after injection of Gd-DTPA contrast agent was significantly higher than before injection,with statistical difference(P<0.05);Meanwhile the FA value on peritumoral tissue was also higher than before injection,with significant difference(P<0.05),while the contralateral brain tissue was no significant difference(P>0.(05).Conclusion:(1)The DTI parameter FA value is expected to provide accurate,reliable and non-invasive imaging information for grading diagnosis of glioma in rats,and it has higher diagnostic efficiency,and also provides experimental basis for clinical glioma grading.(2)the FA value of tumor and peritumoral artificially increased by DTI scan in the late stage of C6 glioma after intravenous injection of Gd-DTPA for 6 min.while no significant effect on contralateral brain.Therefore,DTI scan should be completed before the injection of contrast agent.Part ? The relationship between fractional anisotropy value of ratC6 glioma and its microstructure and its clinical applicationObjective:To explore the relationship between fractional anisotropy(FA)and tumor microarchitecture(percentage of VEGF positive cells.MVD and cell density)in rat C6 glioma tumor and its clinical application value.Materials and MethodsRat C6 glioma model and 30 patients with glioma were enrolled in the DTI examination to obtain FA value and obtained tumor grade,percentage of VEGF positive cells,MVD and cell density by pathological examination;The FA value of different grades of glioma tumors and the correlation between the FA value of the tumors(especially the late stage tumor-bearing rats)and their microstructure were analyzed.P<0.05 was considered statistically significant.Results:(1)The FA value of the tumors of mouse glioma and glioma was lower than that of the contralateral brain tissue,and the difference was statistically significant.The average FA of grade III gliomas was lower than that of grade IV gliomas,and the difference was not statistically significant.(2)The FA value of rat glioma tumors was positively correlated with the percentage of VEGF positive cells,MVD and cell density.r values were 0.62.0.62 and 0.69,respectively,while the rvalues in the late stage were 0.67.0.65 and 0.71(P<0.05),respectively.(3)The FA value of glioma patients was positively correlated with the percentage of VEGF positive cells.MVD and cell density,and the r values were 0.68,0.65 and 0.63(P<0.05),respectively.Conclusion:The FA value of glioma can preoperatively provide an accurate,reliable and noninvasive imaging monitoring method to evaluate the microstructure of glioma(cell density,the extent of angiogenesis,fiber bundle integrity and tumor cell infiltration and so on),predict the biological behavior of the tumor and make out surgical plan,and It also provides experimental basis and clinical application basis for clinical evaluation of glioma microstructure by FA value. |
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