FIG 1. Representative K^trans maps from (A) a grade II fibrillary astrocytoma, (B) a grade III anaplastic astrocytoma, and (C) a grade IV glioblastoma multiforme. The white boxes enclose the tumor area in each image. Note that vasculature does not appear in these maps, and K^trans values in normal brain are insignificant and consistent with noise. The K^trans values in the grade II tumor (A) are insignificant corresponding to the lack of enhancement with contrast. The high-grade-defining necrotic core is clearly evident in the middle of the tumor in panel C. The heterogeneity of K^trans is clearly evident in the enhancing tumor portion in panels B and C.