Accordingly, the [89Zr]Zr-trastuzumab: [111In]In-IgG uptake ratio in these HER2-negative tumours was 1.0 ± 0.1 and this was in close agreement with volume-of-interest analysis of the reconstructed images which yielded a ratio of 1.3 ± 0.3 (P > 0.05). Here, ERBB2 is linked to neoplasm.