IDH genotypes differentiation in glioblastomas using DWI and DSC-PWI in the enhancing and peri-enhancing region

Isocitrate dehydrogenase (IDH) mutation has diagnostic and prognostic values in glioblastomas. Peritumoral invasion of glioma cells is a cardinal feature of glioblastomas.

To evaluate the contribution of DWI and DSC-PWI in the enhancing and peri-enhancing region for discriminating glioblastomas IDH genotypes, and the diagnostic values of combining two techniques in the peri-enhancing region compared with those in the enhancing region.

We retrospectively reviewed the conventional MRI (cMRI), DWI and DSC-PWI obtained from 10 patients with IDH-mutated (IDH-m) glioblastomas and 65 patients with IDH wild-type (IDH-w) glioblastomas. Features of cMRI, relative minimum ADC in the enhancing region (rADC_min-t) and peri-enhancing area (rADC_min-p), and relative maximum CBV values in the enhancing region (rCBV_max-t) and peri-enhancing region (rCBV_max-p) were compared between two groups. Receiver operating characteristic curves and logistic regression analysis were used to assess diagnostic performance.

IDH-m glioblastomas tended to present in frontal lobes and younger patients. The rADC_min-t (P = 0.042) were significantly lower in IDH-w than IDH-m. Both rCBV_max-t and rCBV_max-p showed significant differences between two subgroups (all P < 0.001). The optimal cutoff values in prediction of IDH-m were >0.98 for rADC_min-t, <7.27 for rCBV_max-t, and < 0.97 for rCBV_max-p. Multivariate logistic regression revealed that the combination of rADC_min-t and rCBV_max-t yielded the highest sensitivity and specificity.

The rCBV_max-t or rCBV_max-p may serve as preferable and comparable imaging biomarkers for evaluation of glioblastomas IDH status. The combination of rADC_min-t and rCBV_max-t may yield the maximum predictive power for differentiating IDH status.