Figure 14:CT-CBV maps from four contiguous slice locations in a patient undergoing stereotactic biopsy of a left basal ganglia tumor. The arrow corresponds to the region of highest blood volume, which revealed Grade III anaplastic astrocytoma on biopsy. This region did not demonstrate contrast enhancement on conventional MRI. Of note, the remaining portions of the tumor, some of which were contrast enhancing, but which had less marked elevation of blood volume, were all low-grade at biopsy. This is consistent with studies showing a better correlation between tumor grade and CBV, than between tumor grade and contrast enhancement.