Preoperative assessment of intratumor heterogeneity using intravoxel incoherent motion MRI for survival prediction in high-grade gliomas: a feasibility study

BACKGROUND: Intratumor heterogeneity (ITH) is closely associated with poor prognosis in high-grade gliomas (HGGs). This study aimed to characterize ITH and explore potential imaging markers that predict overall survival (OS) in HGGs using intravoxel incoherent motion magnetic resonance imaging (IVIM MRI)-based spatially explicit analysis. METHODS: Sixty-five HGG patients who underwent surgical resection were analyzed. Preoperative IVIM MRI images were collected and processed to obtain true diffusion coefficient (D) and perfusion fraction (f) maps. Tumor regions of interest were segmented, and the k-means algorithm was applied to cluster the D and f image voxels for generating spatial habitats and extracting quantitative image features. Kaplan-Meier analysis and Cox proportional hazards were used to compare variables and patient subgroups. RESULTS: Three spatial habitats were identified: Habitat 1 (hypo-vascular, hyper-cellular), Habitat 2 (hypo-cellular), and Habitat 3 (hyper-vascular). In the multivariate Cox regression analysis, isocitrate dehydrogenase (IDH) genotype (hazard ratio [HR] = 0.298, P = 0.003) and volume percentage (pVol) of Habitat 1 (HR = 6.155, P = 0.01) showed prognostic significance, with the model yielding a concordance index of 0.756. A pVol value of Habitat 1 below 47.6% predicted survival benefits in patients with HGG and IDH wild-type gliomas, as well as in those with HGG who underwent subtotal resection (median OS improvement: 11, 11, and 8 months, respectively). CONCLUSIONS: Spatial habitats identified via IVIM MRI may aid in characterizing cellular and vascular heterogeneity in HGGs, with the pVol of hypo-vascular, hyper-cellular habitat potentially serving as an independent predictor of patient survival.