Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (Miniantibody) is a fusion protein of two scFv fragments combined with distinct specificity. One scFv of an anti-CEA antibody variable domain is linked to another scFv of an anti-DTPA antibody variable domain by a flexible hinge region. This BsAb format has the decreased size and better penetration than conventional IgGs in the clinical diagnostics and potentially therapy. This BsAb can be used in pretargeting system of PET, radioimaging or radiotherapy. It can mediate targeting of radioactivity to tumor cells. It is designed for the research of Breast cancer; Ovary cancer; Colon cancer; Lung cancer imaging and therapy.