FIG 1. Parametric images of rCBV (left) and rR (right) in a patient with glioblastoma multiforme. The rCBV map is in color to aid interpretation. The color scale is nonlinear: black, 2%; blue, 2–5%; green, 5–10%; red, 10–30%; orange, 30–80%; and yellow, 80%. The image demonstrates large peripheral vessels (yellow) and a central area of high rCBV within the tumor core (red) and other central areas of poor perfusion or necrosis (black). The red areas in the rR map indicate pixels with values <0.46, which are seen in fewer than 2% of normal tissue. Single-pixel areas of elevated rR have been filtered out, and the pixel clusters have been filtered by using a 0.5-pixel gaussian filter. The underlying gray-scale image shows the rCBV map. This image demonstrates areas of elevated rR, which occur principally in the center of the tumor, adjacent to areas of necrosis and away from the central area of elevated rCBV.