Tumor accumulations of Cy5.5-Tf-DTPA-Gd were 1.35±0.05×109 phto/cm2/s in target groups, respectively that of in blocking groups decreased to 0.84±0.06×109 phto/cm2/s (p < 0.05) after the competition with free transferrin (Figure 8B). Here, TF is linked to neoplasm.