FIG 2. A, MR image before contrast administration (top left) and six dynamic contrast-enhanced MR images of a grade 2 oligoastrocytoma. Top center, 15 seconds; top right, 45 seconds; middle left, 75 seconds; middle center, 105 seconds; middle right, 135 seconds; and lower left, 165 seconds after contrast administration. From these seven images, spatial maps of fBV and k^PS were determined: fBV (lower center) was estimated as 12.8% in the ventral, enhancing part of the tumor and as 9.3% in the more dorsal part. k^PS values (lower right) were 0.31 mL/100 cm³ per minute in the tumor (compared with 0.02 mL/100 cm³ per minute in normal brain tissue)