Fig. 1.

Top panel: From left to right, i) a T₁-weighted image; ii) tumor blood flow (TBF) map acquired during retest of a 9L tumor in a Fischer-344 rat; iii) the corresponding model selection map; and iv) H & E-stained brain section. A close agreement in distribution of tumor tissue (hyperintense regions on T₁ image, darker regions on CBF map and densely staining tissue on H & E) can be seen between the images (outlined in black). Tumor tissue grew as two nearly separate masses in this rat and all three methods reproduce it distinctly. A small aggregate of tumor cells near the cortical edge can also be seen in both T₁ and H & E. The model selection map shows in yellow pixels within the white outline the Model 3 regions selected for a typical analysis. Note that in this example not all tumor tissue is encompassed by yellow pixels or model 3 region. The dark red pixels around the yellow pixels represent Model 2 regions with leakage, but no backflux. The bright red regions are Model 1 regions with no MRCA leakage. The other hyperintense regions on T₁, dark areas on CBF and yellow pixels on model selection map are water/proton-rich brain ventricles (white 3-headed arrow) and pial vasculature.