ERBB2 and neoplasm: Provided that administered doses of radioactivity and acquisition times were sufficient to yield good counting statistics, we conclude that either microSPECT/CT with 111In-DOTA-trastuzumab Fab or microPET/CT with 64Cu-DOTA-trastuzumab Fab visualized small (5 to 10 mm diameter) or larger (10 to 15 mm diameter) s.c. tumor xenografts with low, intermediate, or high HER2 expression in athymic mice.