CEACAM5 and neoplasm: The favorable in vivo targeting properties of [99mTc]Tc-C9-C9 are in agreement with previous experiences with other affibody constructs, tested for in vivo radionuclide molecular diagnostics and used e.g. for clinical imaging of HER2-expressing tumors [13,46] 99mTc]Tc-C9-C9 compares favorably with immunoglobulin-based imaging agents that bind specifically to CEA, including scFv-Fc H310A showing 2.8 ± 1.1 %ID/g 20 h post injection, and a tumor-to-blood ratio of 5.7 [20].