Gd concentration maps showing Gd-dendrimer distribution within the largest and smallest gliomas of each generation over time. A) Gd-G5, Gd-G6, and Gd-G7 dendrimers slowly accumulate within the extravascular tumor space of the largest RG-2 gliomas within the size range of tumors in the study. Gd-G8 dendrimers remain intravascular. The volume, in mm3, for each tumor shown is 104 (Gd-G1), 94 (Gd-G2), 94 (Gd-G3), 162 (lowly conjugated Gd-G4), 200 (standard Gd-G4), 230 (Gd-G5), 201 (Gd-G6), 170 (Gd-G7), and 289 (Gd-G8). B) Gd-G5 and G6 dendrimers still slowly accumulate within tumor tissue of the smallest RG-2 gliomas, which have a minimally compromised blood-brain tumor barrier. Gd-G7 dendrimers are impermeable to the BBTB of the smallest RG-2 gliomas and remain intravascular. Gd-G8 dendrimers continue to be impermeable to the blood-brain tumor barrier of the smallest RG-2 gliomas. The volume, in mm3, for each tumor shown is 27 (Gd-G1), 28 (Gd-G2), 19 (Gd-G3), 24 (lowly conjugated Gd-G4), 17 (standard Gd-G4), 18 (Gd-G5), 22 (Gd-G6), 24 (Gd-G6), and 107 (Gd-G8). Each animal received an intravenous 0.09 mmol Gd/kg bw.