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. 2021 May 28;15:666679. doi: 10.3389/fnins.2021.666679

FIGURE 1.

FIGURE 1

Conceptual schematic illustration of glioma microenvironment classifying the tumor into three heterogeneous tumor zones (TZ I–III). (A,B) An illustrative representation of TZ I–III. (C) A schematic illustration of glioma microenvironment showing the cellular level of TZ I–III. TZ I comprises the tumor core cells and can be spotted as the contrast-enhancing regions on magnetic resonance imaging (MRI) (D). TZ II, the most biologically active area of the tumor can be observed on MRI as the area of perifocal edema (E), which is characterized by its specific pro-angiogenic microenvironment and the presence of glioma-associated microglia/macrophages (GAM) and transitory cells. TZ III consists mainly of healthy brain tissue and contains isolated partisan cells, which are probably responsible for tumor recurrence following surgery. (D,E) Illustrative MRI scans of a patient with a right parietal glioblastoma (WHO grade IV) by using a 1.5 tesla Ingenia scanner (Philips Healthcare, Best, Netherlands). (D) A T1-weighted contrast-enhanced gradient-echo imaging (CE-GRE-T1WI), demonstrating the TZ I (arrow). (E) A T2-weighted spin-echo imaging (SE-T2WI), showing the TZ II (arrow).