RTN4R and neoplasm: A decrease of radioactivity was observed in all dissected tissues and organs similar to SPECT imaging results in blocking group (Table 2), with the change of tumor uptake being the most significant reducing markedly from 2.52 ± 0.83% ID/g whereas the presence of nonlabeled NGR peptide significantly reduced to 1.65 ± 0.61% ID/g at 1 h after injection.