Intravoxel Incoherent Motion Metrics as Potential Biomarkers for Survival in Glioblastoma

OBJECTIVE: Intravoxel incoherent motion (IVIM) is an MRI technique with potential applications in measuring brain tumor perfusion, but its clinical impact remains to be determined. We assessed the usefulness of IVIM-metrics in predicting survival in newly diagnosed glioblastoma. METHODS: Fifteen patients with glioblastoma underwent MRI including spin-echo echo-planar DWI using 13 b-values ranging from 0 to 1000 s/mm(2). Parametric maps for diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were generated for contrast-enhancing regions (CER) and non-enhancing regions (NCER). Regions of interest were manually drawn in regions of maximum f and on the corresponding dynamic susceptibility contrast images. Prognostic factors were evaluated by Kaplan-Meier survival and Cox proportional hazards analyses. RESULTS: We found that f(CER) and D*(CER) correlated with rCBF(CER.) The best cutoffs for 6-month survival were f(CER)>9.86% and D*(CER)>21.712 x10(−3)mm(2)/s (100% sensitivity, 71.4% specificity, 100% and 80% positive predictive values, and 80% and 100% negative predictive values; AUC:0.893 and 0.857, respectively). Treatment yielded the highest hazard ratio (5.484; 95% CI: 1.162–25.88; AUC: 0.723; P = 0.031); f(CER) combined with treatment predicted survival with 100% accuracy. CONCLUSIONS: The IVIM-metrics f(CER) and D*(CER) are promising biomarkers of 6-month survival in newly diagnosed glioblastoma.