Fig. 4.

Contrast enhancement over time in U87 versus hTSC tumors. a MR image slices acquired for a U87 tumor, at two timepoints separated by 14 days. The upper panels marked ‘start’ are the first pair of T2W and T1W post contrast images. For the U87 tumor the initial and final ‘end’ acquisitions show the same degree of strong enhancement, even though they differ in size. Note the smooth outline of the tumor at 14 days. b MR images, 14 days apart, acquired for an hTSC tumor. The initial acquisition shows little or no enhancement, while the 14 day acquisition has strong enhancement. Note the irregular outline of the tumor in the contrast enhanced image at the second timepoint. c Quantitative representation of contrast enhancement for U87 tumors, for hTSC tumors at beginning of 2-week period ‘start’ and at conclusion of 2-week period ‘end’. The U87 contrast versus hTSC at start of period differed significantly (P = 0.0001; parametric, unpaired T-test), and the start hTSC contrast differed from that at the end (P = 0.0002). The mean (line x), the range (box) and the standard deviation (bars) are indicated for each group