18F-FDG (left) and 89Zr-trastuzumab PET scans (right) of three patients: Example of a patient with a 89Zr-trastuzumab PET scan considered HER2-positive (a), a 89Zr-trastuzumab PET scan considered HER2-negative (b) and an 89Zr-trastuzumab PET scan considered equivocal (c). Reprinted under a Creative Commons (CC BY 4.0) license from: Bensch F, Brouwers AH, Lub-de Hooge MN, de Jong JR, van der Vegt B, Sleijfer S, de Vries EGE, Schröder CP. 89Zr-trastuzumab PET supports clinical decision making in breast cancer patients, when HER2 status cannot be determined by standard work up. Eur J Nucl Med Mol Imaging. 2018 Dec;45(13):2300–2306.