FIG. 2.

Representative image of an axial T₁-weighted postcontrast sequence (a), a corresponding color coded “relative enhancement map” of a dynamic contrast enhanced three-dimensional T₁-weighted sequence (b), and signal intensity (SI) curves of different tumor areas (c) in a patient with glioblastoma multiforme. Areas with a strong uptake of contrast media show high SI values during the first 2 min with a subsequent wash out phenomena (blue region of interest and blue curve), which is indicative of a substantial microvascular leak with progressive accumulation of contrast agent in the tumor interstitial space. Areas with lower microvascular permeability values show a less pronounced tumor enhancement (pink region of interest and pink curve), whereas necrotic tumor areas only show a minor uptake of contrast media (black region of interest and black curve). Tumor heterogeneity and different areas of microvascular permeability within an individual tumor mass are characteristic findings for malignant tumors and are only visible on dynamic imaging sequences (b) and not on conventional MRIs (a).