The Correlation Between The Susceptibility Artifacts During Magnetic Resonance Imaging And The Pathologic Grading Of Gliomas

Objective:To investigate the dependablity of the correlation between Magnetic Susceptibility Artifact in Turbo spin echo and Dual Fast Low Angle Shot Imaging with the pathologic grading of gliomas during MR imaging.To analyze the histopathological basic of this imaging signs.And discuss the value of this MR imaging technology for clinical application in gliomas' preoperative grading and prognostic evaluation.Materials:60 patients diagnosed as neurospongioma by histopathological examination were analyzed retrospectively,all cases were examined by MR Spin-echo T₁-weighted imaging,Turbo Spin-echo T2-weighted imaging and dual Fast Low Angle Shot T₂^*-weighted imaging(TE=15,35ms),all sequence parameters were set by same field of view,matrix,slice thickness,slice distance and number of slice.All data were dealed as follow procedure:â‘ Compare the difference of Susceptibility artifacts including number,max-diameter and SNR in tumor region between Turbo Spin-echo T₂-weighted imaging and Dual FLASH T₂^*-weighted imaging(TE=15,35 ms) separately.â‘¡According to the standard of WHO 2000 glioma pathology,Pathology results were divided into gradeâ… to gradeâ…£,the correlation between glioma grade and conventional imaging features(size, necrosis,degree of enhancement,hemorrhage and peripheral edema of tumor) were analyzed by Pearson and Spearman rank test.The relationship between Glioma grade and the features(artifact number,size and signal noise ratio) of magnetic Susceptibility Artifacts(MSA) in FLASH sequence(TE=35ms,the same below) were compared by the same method(Pearson and Spearman rank test).Glioma grade were set as a dependent variable Y,the number of magnetic-sensitive artifacts, size and SNR as the independent variables X1,X2,X3,Logistic Regression Analysis between Y and X were processed.â‘¢Ki-67 expression and microvessel density(Microvessel Density,MVD) counting of Glioma were operated by Immunohistochemical staining method,ki-67 is divided into 0-(+++) grade.the correlation between the tumor ki-67 expression,MVD and the number,size and SNR of magnetic-sensitive artifacts were analyzed by Pearson and Spearman test, These imaging analysis were experienced by three veteran radiologists,their consensus choice was chooes as the final results,pathology task were completed by experienced general practitioners.Results:â‘ Total 104 focus of MSA were founded with Turbo spin echo T2-Weighted Imaging,the average size of MSA was(0.27±0.03) cm,and the minimum SNR of MSA was(25.82±4.23).Total 308 focus of MSA were founded with FLASH -T2^* Weighted Imaging(TE=15ms),the average size of MSA was (0.51±0.06)cm,and the minimum SNR of MSA was(20.77±2.20).Total 550 focus of MSA were founded with FLASH-T2^* Weighted Imaging(TE=35ms),the average size of MSA was(0.84±0.08)cm,and the minimum SNR of MSA was (14.87±1.88).Statistical significance of focus number of MSA between three sequences were confirmed by rank sum test results(x²=21.331,P=0.010),and statistical significance of focus size and SNR of MSA between three sequences were analyzed by ANOVA(F values were 44.517 and 6.839,P values＜0.05).â‘¡Pearson correlation test showed that no relationship between glioma grade and tumor size,necrosis,peripheral edema of tumor were founded(P value＞0.05),the correlation between glioma grade and degree of enhancement,hemorrhage were testified,correlation coefficient was 0.606(P=0.000) and 0.483(P=0.000) respectively.And the great relationship between glioma grade and number,size and SNR of MSA were confirmed by Pearson test,the correlation coefficient were 0.737(P=0.000),0.624(P=0.000) and -0.528(P=0.000) respectively,the Logistic regression analysis for the relationship between glioma grade and the number,size,the SNR of MSA showed that the number and size of MSA was incorporated into the regression equation,SNR was removed,then the equation was P=1/[1+e-(-1.496+0.939 MSA number+1.039MSA size)].Number and size of MSA was considered as two risk factors for glioma grade,Value of OR were 2.557 and 2.825 respectively.â‘¢Ki-67 positive expression rates in the tissues of gradeâ… ,gradeâ…¡,gradeâ…¢and gradeâ…£of 60 cases were 0.00%,25.00%,23.33%and 36.67%,Spearman rank correlation test showed that Ki -67 labeling index and tumor susceptibility artifact number,size and SNR have relevance,correlation coefficients were 0.687,0.577 and -0.533(P＜0.001).Microvascular distribution in glioma tissues was heterogeneous,and its high density was most commonly founded in normal brain tissue around the edge of the tumor necrosis,cystic degeneration of regional vascular less,an average MVD of 23 cases was(21.17±8.05),which was significantly different from normal brain tissue(9.92±4.36).the correlation between the number,size,SNR of glioma MSA and MVD counting were proofed by Pearson test,the correlation coefficient were 0.799,0.637 and -0.522,P value＜0.001.Conclusion:â‘ the magnetic susceptibility artifacts of gliomas during MR imaging were founded obviously on TSE and FLASH sequence,FLASH sequence with suitable long TE was more useful than TSE sequence for detecting the magnetic susceptibility artifacts of gliomas when MR imaging.â‘¡great relationship between the number,size,SNR of magnetic susceptibility artifacts and gliomas grade were founded in this study,and more number,larger size and decreased SNR of glioma MSA during MR imaging means higher grade for gliomas.â‘¢the correlation between magnetic susceptibility artifacts of gliomas and tumor Ki-67 and MVD suggests that,with regard to magnetic susceptibility artifacts of gliomas during MR imaging,there may be potential basis of the pathology and biochemistry for this imaging signs.