Tumor Imaging with I-131 Labeled F(ab’)₂ Fragments of Monoclonal Antibodies

Abstract

Using radiolabeled F(ab’)₂ fragments of monoclonal antibody associated with a noncirculating cell surface antigen of colon carcinoma, we have demonstrated preferential localization in small deposits of human colon carcinoma. (Images show tumor deposition without background subtraction.) Biologic distribution of the F(ab’)₂ fragments is also evaluated. In 16 patients studied to date, tumor deposits as small as 1.5 cm have been readily visualized on unprocessed images without background subtraction. Optimal imaging time (tumors best defined) is 72-96 hr postadministration.