Figure 3. Diffusion-weighted images and apparent diffusion coefficient images for low- and high-grade glioma.

(A & D) Postcontrast T₁-weighted images, (B & E) diffusion-weighted images obtained at b = 1000 s/mm² and (C & F) the corresponding apparent diffusion coefficient maps for patients with (A–C) grade II astrocytoma and (D–F) recurrent glioblastoma, respectively. The bright signal on diffusion-weighted images can result from some combination of restricted diffusion and T₂ hyperintensity, the latter of which can occur within edematous tissue, for example. The apparent diffusion coefficient maps eliminate T₂ contributions so that restricted diffusion, shown as areas of darker image intensity, can be more clearly delineated. In turn, restricted diffusion may represent areas of increased tumor cell density.