Angiogenic Signalling Pathways Altered in Gliomas: Selection Mechanisms for More Aggressive Neoplastic Subpopulations with Invasive Phenotype
Figure 1
Brain coronal sections of Sprague Dawley rats exposed prenatally to ethylnitrosourea. Two columns show MRI on T1-w and T2-w after gadolinium administration and the left column shows the necropsy thirty minutes after Evans Blue i.v. injection (a, b) or Indian ink (c). (a) On T2-weighted images, tumours in the early development stage show a diminutive proliferation mass growing in association with the subcortical white matter. The blood brain barrier (BBB) remains still intact, shown by the lack of contrast or dye extravasation (microtumours). (b) Multiple tumours on the intermediate development stage. There is a BBB dysfunction indicated by extravasation of Evans Blue and by gadolinium enhancing the contrast on T1 images (macrotumours). (c) A macrotumour in the advanced stage growing over a whole hemisphere. It displays a heterogeneous signal on T2 and on T1 due to the presence of histopathological features of malignancy such as haemorrhages, cysts, and necrosis. With Indian ink, brains show in black a ring of aberrant vessels surrounding the neoplasia. The same typical shape of glioblastoma multiforme may be observed on MRI in T1 with gadolinium.
