The Application Of 3D PCASL And DWI In Diffuse Gliomas Grading And IDH1 Mutation Status

PurposeTo noninvasively evaluate diffuse gliomas using three-dimensional pseudo-continuous arterial spin labeling（3D pCASL）and diffusion weighted imaging（DWI）:（1）Discussing the value of 3D pCASL and DWI in different grading;（2）Discussing the value of 3D pCASL and DWI in different isocitrate dehydrogenase（IDH）1 mutation status.MethodsFifty-six patients with pathologically confirmed diffuse gliomas according to the 2016world health organization（WHO）classification of tumors of the central nervous system were enrolled in this study,and the IDH1 mutation status was assessed by pyrosequencing.No magnet resonance imaging（MRI）scan was performed before operation or chemoradiotherapy.The MRI scanning sequence included T₁WI,T₂WI,FLAIR,3D pCASL,DWI and enhanced T₁WI.（1）The Student’s t-test and Mann-Whitney U test were used to evaluate differences in parameters of 3D pCASL(CBF_mean、CBF_max、rCBF_mean and rCBF_max)and DWI(ADC_meanean and ADC_min)between low and high grade diffuse gliomas.The results with a p value of less than 0.05 were considered statistically significant.Receiver operator characteristic（ROC）analysis was used to assess the diagnostic performance.Subsequently,a multivariate stepwise logistic regression analysis was used to identify the independent parameters.Besides,Kruskal-Wallis H test was used to examine the differences among gradesⅡ,ⅢandⅣdiffuse gliomas,and the p value was adjusted.（2）The Student’s t-test and Mann-Whitney U test were used to evaluate differences in parameters of 3D pCASL(CBF_mean、CBF_max、rCBF_mean and rCBF_max)and DWI(ADC_meanean and ADC_min)between mutant IDH1 and wild-type IDH1 in gradesⅡ-Ⅲastrocytic tumors.The results with a p value of less than 0.05 were considered statistically significant.Results（1）The values of CBF_max（p=0.012）,rCBF_mean（p=0.004）and rCBF_max（p=0.002）of high grade diffuse gliomas（HGDG）were significantly higher than those of low grade diffuse gliomas（LGDG）,while the values of ADC_mean（p<0.001）and ADC_min（p<0.001）were significantly lower than those of LGDG.In the ROC analysis,the area under the curve（AUC）values of CBF_max,rCBF_mean,rCBF_max,ADC_mean and ADC_min were 0.701,0.730,0.746,0.810 and 0.856,respectively.In multivariate analysis,only the value of ADC_min was identified as the independent parameter in the differentiation of low from high grade diffuse gliomas.All parameters but CBF_mean showed significant differences among the three grades.（2）In this study,the frequencies of IDH1 mutation in gradesⅡ,ⅢandⅣwere81.82%（18/22）,66.67%（6/9）and 0%（0/25）.The frequency of IDH1 mutation in oligodendroglial tumors was significantly higher than in astrocytic tumors（p<0.001）.As neither the oligodendroglial tumors with wild-type IDH1 nor glioblastomas（GBMs）with mutant IDH1 were found in our study,we stratified grade II and III astrocytic tumors according to the IDH1 mutation status to compare the parameters of DWI and 3D pCASL.And we found that mutant IDH1(IDH1_mt)group showed lower perfusion and higher ADC values compared with wild-type IDH1(IDH1_wt)group.We found that the values of CBF_mean（p=0.040）,CBF_max（p=0.029）and rCBF_mean（p=0.027）in IDH1_mt group were significantly lower than those in the IDH1_wt group,and the ADC_mean value in IDH1_mtt group was significantly higher than in IDH1_wt Group（p=0.027）.ConclusionsBoth 3D pCASL and DWI could be useful tools for distinguishing low from high grade diffuse gliomas,and have the potential to differentiate different IDH1 mutation status of astrocytoma,which could be helpful to estimate the malignant degree of gliomas before operation,to make individualized treatment plan and to evaluate the prognosis.