FIGURE 1.

FLAIR-tumor and CE-tumor segmentations on different MRI sequences. (A) T1-weighted contrast-enhanced imaging: the CE-tumor volume is contoured in green, including the enhancing tissue and necrotic core only. (B) FLAIR images: FLAIR-tumor is contoured in orange, including both the CE-tumor and the peritumoral hyperintensity. (C) MD map elaborated from DTI acquisition. (D) rCBV map elaborated from DSC MR perfusion acquisition. (E) VP map elaborated from DCE MR perfusion acquisition (F) Ktrans map elaborated from DCE MR perfusion acquisition. (G) 18F-FAZA-PET uptake showing hypoxic areas. (H) Prototype of clusters resulting from the application of the spatial habitat imaging algorithm only to the contrast-enhanced tumor volume (CE-tumor); clusters obtained this way were considered too small and fragmented in order to be reliably correlated to histology, and therefore not suitable for the purpose of the present study. (I) Habitats obtained applying the spatial habitat imaging algorithm to the FLAIR-tumor volume (which included the contrast-enhanced tumor core along with the surrounding area of FLAIR hyperintensity) were able to divide the whole tumor in a more reproducible way, with larger clusters amenable to a reliable histological correlation with the bioptic samples obtained; for the aforementioned reasons we selected FLAIR-tumor as the final tumor mask to be investigated and all the results presented in our paper are based on its analysis.