The Application Value Of Diffusion Tensor Imaging Fiber Density Index Of Peritumoral Fibers In Glioma Grading And Its Correlation With Ki-67

Objective: To investigate the study on diffusion tensor imaging(DTI)quantitative parameters of peritumoral fibrous tracts in glioma,the application value of fiber density index(FDi)in the diagnosis of glioma grading comparing with other DTI parameters and its correlation with Ki-67.Methods: This experiment retrospectively collected 125 patients with brain tumors who were admitted to our hospital from August 2015 to August 2018 and were examined by DTI before surgery.After removing the patients who did not meet the experimental requirements,45 patients with brain gliomas confirmed by surgery and pathology were included,including 25 high-grade gliomas and 20 low-grade gliomas.All clinical data of45 patients with gliomas were collected and collated.The Positive expression rate of Ki-67 in all patients were recorded.We used DSI-studio software to post-process the original DTI data of all patients.The number of reconstructed fiber bundles was affected by FA threshold of post-processing software.Thus,Firstly,the FDi values of the reconstructed fiber bundles obtained under different FA thresholds were analyzed to determine the optimal FA threshold for DSI-studio software to reconstruct the fiber bundles,and then the fiber bundles reconstruction was performed under the optimal FA threshold.The FA gray-scale image,MD gray-scale image,FA color-coded image were obtained.Based on FA color-coded image,the fiber bundles adjacent to the tumors were tracked,reconstructed and identified,and at the maximum level of the tumor body and its upper and lower 2-3 levels to select the best level of peritumoral fibrous tract display to manually delineate ROI,ensure that all ROIs were located in the reconstructed fibrous tract and placed on the identifiable peritumoral fiber bundles adjacent to the tumors and the corresponding fibers in the contralateral normal cerebral hemisphere.Recorded and calculated the quantitative parameters in the ROI of peritumoral fibrous tract and contralateral normal cerebral hemisphere fibers in high and low grade glioma groups.The parameters included fiber density index(FDi),anisotropic fraction(FA),mean diffusion coefficient(MD)and its relative values(rFDi,rFA,rMD).SPSS 25.0 and MedCalc 15.2.2 software were used for statistical analysis: The optimal FA threshold wasdetermined by comparing the difference in FDi values of reconstructed bundles under different FA thresholds;At the optimal FA threshold,the differences of FDi values,FA values,MD values and their relative values(rFDi,rFA,rMD)of peritumoral fibrous bundles between high and low-grade gliomas were compared;and the diagnostic efficiency of the parameters with statistical differences were analyzed by using ROC curve;The positive expression rate of Ki-67 in high and low grade glioma tumors were analyzed,and its correlation with FDi and rFDi values of peritumoral fibrous bundles were obtained.Results: 1.When the FA threshold was 0.10,the FDi value of the normal side reconstructed fibers was slightly higher than that of the tumor side,and the difference was not statistically significant(P=0.361);When the FA threshold=0.16,0.22,0.28,the FDi values of normal reconstructed cellulose were significantly higher than that of tumor side(P<0.05).FA thresholds were 0.16,0.22 and 0.28,respectively,the FDi values of normal reconstructed bundles had no difference among three groups(P=0.481).Setting FA thresholds were 0.16,0.22 and 0.28,there was no significant difference in FDi values of the tumor side fibers between 0.22 and 0.28(P=0.874);when FA threshold was 0.16,FDi value of fibrous bundles was significantly higher than those of 0.22 and 0.28,0.16 was the optimal FA threshold for reconstructing fibrous bundles.2.Setting the FA threshold of 0.16,the FDi,FA,MD and their relative values of peritumoral fibrous bundles in high and low grade gliomas were measured.The values of FDi?FA?rFDi?rFA in high-grade gliomas were lower than that in low-grade gliomas.The MD value and rMD value of high-level group were higher than that of low-level group.There were significant differences in DTI parameters between high and low level groups(P<0.05).The area under ROC curve of the parameters were all above 0.70,and the FDi value and rFDi value corresponded to the maximum area under the curve of 0.906 and0.925.3.The positive expression rate of Ki-67 in low-grade gliomas was lower than that in high-grade gliomas(P<0.05).There was a negative correlation between the expression level of Ki-67 and the value of FDi and rFDi in peritumoral fibrous in 45 patients with gliomas(r=-0.671,r=-0.501),P<0.05.Conclusion: Compared with FA value and MD value,the FDi value of peritumoralfibrous bundles has higher diagnostic efficiency in differentiating high and low grade gliomas before operation,and the FDi value is negatively correlated with the proliferative activity of gliomas.It has higher application value in the preoperative grading and prognosis of gliomas.