Purpose In this study we developed and tested an iron oxide nanoparticle conjugated with DTPA and Trastuzumab, which can efficiently be radiolabeled with 99m-Tc and Ga- 68, generating a nanoradiopharmaceutical agent to be used for SPECT and PET imaging. Methods The production of iron oxide nanoparticle conjugated with DTPA and Trastuzumab was made using phosphorylethanolamine (PEA) surface modification. Both radiolabeling process was made by the direct radiolabeling of the nanoparticles. The in vivo assay was done in female Balb/c nude mice xenografted with breast cancer. Also a planar imaging using the radiolabeled nanoparticle was performed. Results No thrombus and immune response leading to unwanted interaction and incorporation of nanoparticles by endothelium and organs, except filtration by the kidneys, was observed. In fact, more than 80% of 99mTc-DTPA-TZMB@Fe3O4 nanoparticles seems to be cleared by the renal pathway but the implanted tumor whose seems to increase the expression of HER2 receptors enhancing the uptake by all other organs.