Assessment of the neovascular permeability in glioma xenografts by dynamicT1MRI with Gadomer-17

The uptake of Gadomer-17, as probed by fast dynamic T(1) measurements, was used to assess the vascular permeability surface-area product per leakage volume of tissue (k(Tofts)) of human glioma xenografts implanted in mice. With this approach we could discriminate between two types of glioma xenograft lines with a known difference in the perfused vascular architecture and degree of hypoxia. The T(1) data were analyzed according to the Tofts-Kermode compartment model. The fast-growing E102 tumor demonstrated a homogeneous distribution of the vascular permeability surface area across the tumor (mean k(Tofts) value = 0.18 +/- 0.05 min(-1)). The slowly growing E106 tumor showed a more heterogeneous pattern. Three perfused tumor areas with differences in vascular permeability surface area could be distinguished: a well-perfused periphery with high k(Tofts) values (0.24 +/- 0.04 min(-1)), perfused capillaries inside the tumor with low k(Tofts) values (0.108 +/- 0.026 min(-1)), and perfused capillaries adjacent to necrotic regions with high k(Tofts) values (0.29 +/- 0.10 min(-1)). On a different series of tumors, the hypoxic fractions were measured, and these were significantly higher in E106 tumors (0.14 +/- 0.05) compared to tumors of the E102 line (0.03 +/- 0.02).