IDH Genotypes Differentiation In Glioblastomas Using DWI And DSC-PWI

Purpose:To evaluate the contribution of diffusion weighted imaging（DWI）or dynamic susceptibility contrast-enhanced perfusion weighted imaging（DSC-PWI）in the enhancing and peri-enhancing region for discriminating glioblastomas IDH genotypes.And to explore the diagnostic value of combining two techniques in the peri-enhancing region compared with those in the enhancing region in order to improve the accuracy of preoperative diagnosis.Material and Methods:We retrospectively reviewed 10 patients with IDH-mutated（IDH-m）glioblastomas and 65 patients with IDH wild-type（IDH-w）glioblastomas confirmed by pathology from July 2013 to September 2017.All patients underwent conventional magnetic resonance imaging（cMRI）,DWI and DSC-PWI.The cMRI features,including tumor location,size,number,contrast enhancement pattern,necrosis,cyst degeneration,hemorrhage,tumor border,edema and mid-line shift were analyzed.The relative minimum ADC value in the enhancing region(rADC_min-t)and peri-enhancing area(rADC_min-p),and relative maximum CBV value in the enhancing region(rCBV_max-t)and peri-enhancing region(rCBV_max-p)were obtained from enhancing solid portion of the lesion,peri-enhancing region（defined as peritumoral non-enhancing region with T2-FLAIR hyperintensity,<1cm）and contralateral normal-appearing white matter,respectively.All categorical variables were compared by the Pearsonχ² test or Fisher’s exact test.All quantitative data were compared by a two-sample t test or Mann-Whitney U test between groups.A paired t test was performed to compare rADC_min-t with rADC_min-p in IDH-m or rCBV_max-t with rCBV_max-pax-p in IDH-w,whereas Wilcoxon test was used to compare rADC_min-t with rADC_min-p in IDH-w or rCBV_max-t with rCBV_max-p in IDH-m.Receiver operating characteristic curve（ROC）and logistic regression analysis were used to evaluated the diagnostic performance of univariate and multivariate MR parameters to determine the optimal diagnostic protocol.Results:IDH-m glioblastomas tended to present in frontal lobes and younger patients.The rADC_min-p values were significantly higher than the rADC_min-t values in IDH-w（P<0.001）or IDH-m（P=0.006）.The rADC_min-t（P=0.042）were significantly lower in IDH-w than IDH-m.The rCBV_max-p values were significantly lower than the rCBV_max-tax-t values in IDH-w or IDH-m（all P<0.001）.Both rCBV_max-t and rCBV_max-p showed significant difference between two subgroups（all P<0.001）.On the basis of univariate logistic regression analysis,the area under the curve（AUC）of rCBV_max-t（AUC=0.879）was comparable with that of rCBVmax-p（AUC=0.886）,and both of them were higher than the AUC of rADC_min-t（AUC=0.703）.The optimal cutoff values of rADC_min-t,rCBV_max-t and rCBV_max-pax-p in prediction of IDH-m glioblastomas were>0.98,<7.27 and<0.97,respectively.The corresponding sensitivity and specificity were90.00%/55.93%、100.00%/70.77%和80.00%/96.92%,respectively.The combination of rADC_min-t and rCBV_max-t accounted for the highest AUC（0.895）in differentiating IDH-m from IDH-w glioblastomas,with sensitivity and specificity of 100.00%and77.97%,respectively.Conclusions:The rADC_min-t,rCBV_max-t or rCBV_max-p may serve as imaging biomarkers for evaluation of glioblastomas IDH status.The diagnostic value of DSC-PWI was superior to that of DWI with a comparable performance between rCBV_max-t and rCBV_max-p.The combination of rADC_min-t and rCBV_max-t may yield the maximum predictive power and serve as the optimal model for differentiating IDH status in glioblastomas.