In the end, this pilot investigation has clearly demonstrated that [89Zr]Zr-DFO-AR20.5 is an effective tool for the non-invasive delineation of MUC1-expressing tumor tissue, and we are hopeful that in the future, this radioimmunoconjugate can play an important role in the clinical diagnostic and theranostic imaging of ovarian cancer. Here, MUC1 is linked to ovarian carcinoma.