 It is conjugated to a radioactive element, which will label the tumors when viewed with single-photon emission computed tomography.Sulesomab, an antigen that recognizes proteins on the surface of granulocytes, is used to label out infections, again using the 99mTc isotope.Fab fragments are often fused to small proteins (<100 kDa) that have lower scattering, resulting in images with less contrast.