The overall approach was evaluated for its ability to provide high contrast and to differentiate the ER+/HER2− MCF-7 and ER−/HER2+ JIMT-1 human breast tumors in female nude mice and whether it could occur at time points shorter than the 6 days p.i. observed in the clinic for 89Zr-T. Here, ESR1 is linked to breast neoplasm.