Fig. 8

a In vivo SPECT images of the rat intracranial glioma model treated with mPEI-CTX-^99mTc/DOX (T) and mPEI-^99mTc/DOX (NT) at different time points of 0.5, 2, 4, 6, 8, and 12 h, respectively, and b their tumor-to-background ratios (TBR) of the SPECT signal intensities in the brains. c SPECT images of ex vivo brains at 12 h post-injection