Tumor scintigraphy by the method for subtracting the initial image with technetium-99m labeled antibody.
The method for subtracting the initial image from the localization image was evaluated for radioimmunoscintigraphy of tumors with technetium-99m (Tc-99m) labeled antibodies. Monoclonal antibodies were parental mouse and mouse-human chimeric antibodies to carcinoembryonic antigen (CEA), designated F11-39 and ChF11-39, respectively, both of which have been found to discriminate CEA in tumor tissues from the CEA-related antigens. After reduction of the intrinsic disulfide bonds, these antibodies were labeled with Tc-99m. In vivo studies were performed on athymic nude mice bearing the human CEA-producing gastric carcinoma xenografts. Though biodistribution results showed selective and progressive accumulation of Tc-99m labeled antibodies at the tumor site, high radioactivity in blood was inappropriate for scintigraphic visualization of the tumors within a few hours. We examined the subtraction of the initial Tc-99m image from the Tc-99m localization image after a few hours. Subtracted images of the same count reflected the in vivo behavior of the Tc-99m radioactivity. The subtracted scintigrams revealed excellent tumor images with no significant extrarenal background. Visualization of the tumor site was dependent on antigen-specific binding and nonspecific exudation. These results demonstrate that a method of subtraction of the initial image may serve as a potentially useful diagnostic method for an abnormal site for agents with a low pharmacokinetic value.
Karube
Y
Y
Faculty of Pharmaceutical Sciences, Fukuoka University, Japan. karube@fukuoka-u.ac.jp
Katsuno
K
K
Ito
S
S
Matsunaga
K
K
Takata
J
J
Kuroki
M
M
Murakami
M
M
Matsuoka
Y
Y
D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015902:Gamma Cameras; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D016719:Radioimmunodetection / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging*; D013667:Technetium / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D011993:Recombinant Fusion Proteins; D013667:Technetium