Effect of dosing and schedule of sorafenib on tumor perfusion. Figure 3A shows normalized serial tumor perfusion from 3 mice at 4 time points. Conventional dose of sorafenib lowers tumor perfusion by 57% by day 3. This decrease begins to resume by day 10 of therapy. In contrast, high dose intermittent sorafenib lowers perfusion by 85% at day 3. While tumor perfusion increases slightly at day 7 after there has been a 4 day lapse in treatment, by day 10, tumor perfusion is still low (20% of pretreatment). Tumor perfusion was significantly different in two arms at day 3 (P < 0.01) and day 10 (P < 0.001) as determined by two way ANOVA followed by Bonferroni posttest. Data are presented as mean normalized tumor perfusion with SEM. Figure 3B, shows a representative set of serial tumor perfusion images from mice treated with a conventional dose (upper row) or high dose intermittent (lower row) sorafenib. The blood flow values are shown in bold text are the values obtained while the mice were on sorafenib and the values that are not in bold are from mice before or off therapy. The tumor size was measured in long and short axes (mm) and the mean blood flow (mL/100 g/minute) are shown below each image. A color bar at the bottom represents the range of perfusion values from 0 to 160 mL/100 g/minute.