Biodistribution of 99mTc-anti-CEA pIgA-SH, 99mTc-irrelevant pIgA-SH and 99mTc-anti-CEA IgG-SH was subsequently evaluated 4 h post-injection by microSPECT/CT in normal SCID mice and in SCID and Tsg SCID-CD89 colorectal tumour model (n=3 for each Ig and mice model). Here, CEACAM5 is linked to colorectal neoplasm.