Haylock et al. constructed a bivalent CD44v6 targeting Fab antibody fragment linked through a self-dimerizing helix-turn helix motif named AbD19384 as the probe base, which was further labeled with 125I or 124I. 124I-AbD19384 showed superior tumor imaging ability than 18F-Fluoro-2-deoxy-D-glucose (18F-FDG) in CD44 positive breast cancer model MDA-MB-231 bearing mice. Here, CD44 is linked to breast cancer.