Application Study Of Multiparameter MRI Combined With Histogram Analysis In The IDH Genotypes Differentiation Among Lower-grade Astrocytomas

Purpose:Noninvasive prediction of isocitrate dehydrogenase（IDH）genotypes of lower-grade astrocytomas before operation is useful for evaluating the prognosis of patients and making clinical therapeutic decision.The study was to evaluate the value of conventional MRI（c MRI）,dynamic susceptibility contrast-enhanced perfusion weighted imaging（DSC-PWI）and intravoxel incoherent motion（IVIM）imaging combined with histogram analysis in differentiation of IDH genotypes in lower-grade astrocytomas,and improve the diagnostic accuracy of IDH genotypes in gliomas.Materials and Methods:We retrospectively reviewed the epidemiologic feature and imaging data of 33 patients with IDH-mutation(IDH_mt)and 21 patients without IDH-mutation(IDH_wt)lower-grade astrocytomas（WHO grade II and III astrocytomas）,which were confirmed by pathology form July 2016 to June 2020.The c MRI,DSC-PWI and IVIM techniques were performed on all patients.The c MRI futures,including tumor location,peritumoral edema,tumor border,signal and enhancement were analyzed.DSC-PWI and IVIM derived whole-tumor histogram features,including the mean,median,10th percentage,90th percentage,interquartile range,skewness and kurtosis values,were obtained by 3D slicer software.Pearsonχ² test or Fisher’s exact test were used for comparing all categorical variables,while two-sample t test or Mann-Whitney U test were used for comparing all quantitative data.The predicted performance of univariate and multivariate metrics of MRI were analyzed and compared by the receiver operating characteristic（ROC）curves,the De Long test and the binary logistic regression model.The association between the histogram features and IDH genotypes in lower-grade astrocytomas was determined by the multivariate logistic regression analysis.Results:（1）IDH_mt lower-grade astrocytomas were more frequent occurred in frontal lobe than IDH_wt tumors,and 22 cases of 33 IDH_mt tumors（66.67%）were located in the frontal lobe.The peritumoral edema of IDH_wt lower-grade astrocytomas were more obvious than IDH_mt tumors,and 10 cases of 21 IDH_wt tumors（47.62%）presented peritumoral edema（all P<0.05）.（2）For DSC-PWI and IVIM derived histogram metrics,the values of CBV_90th,CBV_IQR,D_kurtosis,D_skewness and D^*_medianvalues of IDH_wt lower-grade astrocytomas were distinctly higher than those of IDH_mttumors,while D_mean,D_median,D_10th,D_90th and D_IQR values of IDH_wtastrocytomas were lower compared to those of IDH_mt tumors（all P<0.05）.The results of the univariate analysis demonstrated that the area under the curve（AUC）value of D_skewness was 0.817,and the sensitivity and specificity were 61.90%and 93.93%respectively.The diagnostic performance of D_skewness were significantly higher than those of CBV_IQRand D^*_median(AUC_Dskewness=0.817,AUC_CBVIQR=0.680,AUC_D*median=0.693).（3）Based on the combination of parameters,the results of the binary logistic regression analysis showed that the combination of c MRI and D_skewness had the best diagnostic accuracy in the prediction of genotypes in lower-grade astrocytomas（AUC=0.903,the sensitivity and specificity were 71.43%and 96.97%respectively）.The combination of c MRI,CBV_IQR and D_skewnesscouldn’t further improve the predictive performance of genotypes in lower-grade astrocytomas（AUC=0.903）.（4）The result of the multivariate logistic regression analysis indicated that the D_skewnessvalue was an independent predictor of IDH genotypes in lower-grade astrocytomas.The IDH genotype of astrocytoma with a higher D_skewness value（>0.37）was more likely to be IDH wild type（OR:19.586;95%CI:2.667-143.826;P=0.004）.Conclusion:（1）The whole-tumor histogram analysis of DSC-PWI and IVIM is useful for predicting IDH genotypes in lower-grade astrocytomas.（2）The combination of c MRI,IVIM and histogram analysis had the best performance in the prediction of genotypes in lower-grade astrocytomas.（3）The D_skewness value was an independent predictor of IDH genotypes in lower-grade astrocytomas.