Medullary-thyroid-carcinoma imaging in an animal model: use of radiolabeled anticalcitonin F(ab')2 and meta-iodobenzylguanidine.

Radiolabeled anti-calcitonin (CT) immunoglobulin fragments (131I-anti-CT F(ab')2) and meta-iodobenzylguanidine (131I-mIBG) were injected into nude mice with a transplanted medullary thyroid carcinoma (MCT). 131I-Anti-CT F(ab')2 proved to be unsuitable for MCT scintigraphic imaging. However, a high mIBG uptake was observed in MCTs, but not in control tumors (mesothelioma). The uptake of mIBG was not modified by the presence of reserpine or pentagastrine. These results are discussed, and it is suggested that mIBG could be an APUD-system marker.