title: Tc-99m dextran: a new blood-pool-labeling agent for radionuclide angiocardiography.
abstract: We have explored the possibility of imaging the cardiac blood pool with dextran (Dx) labeled with Tc-99m (Tc) after Sn2+ reduction. Stannous dextran (SnDx) kits were prepared in advance and labeling was performed by adding Tc-99m. The labeling efficiency was greater than 95%. Technetium-99m dextran (TcDx) was highly stable both in vivo and in vitro. In seven dogs we compared the quality of blood-pool images obtained with TcDx of different molecular weights (4 X 10(4) = Dx-40; 5 X 10(5) = Dx-500; 2 X 10(6) = Dx-2000) and with Tc-99m red blood cells (TcRBC) labeled in vitro, and determined the organ distribution of this new agent by whole-body scanning and blood sampling. TcDx provided high-quality cardiac blood-pool images up to 60 min after injection. The heart-to-lung ratios averaged 3.7 for TcDx-40, 3.9 for TcDx-500, and 5.4 for TcRBC at 60 min. Whereas TcDx-40 showed a relatively rapid initial urinary excretion and TcDx-2000 was degraded rapidly, TcDx-500 demonstrated the best kinetics for blood-pool imaging. Thus, TcDx is a new radiopharmaceutical with high labeling efficiency and stability. It overcomes a number of the limitations of currently used blood-labeling agents and may become useful for blood-pool imaging in man.
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D003911:Dextrans / Q000378:metabolism / Q000652:urine; D004285:Dogs; D004912:Erythrocytes; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D008168:Lung / Q000378:metabolism; D008970:Molecular Weight; D009206:Myocardium / Q000378:metabolism; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D013667:Technetium / Q000378:metabolism / Q000652:urine; D013997:Time Factors; D014915:Whole-Body Counting
chemical_list: D003911:Dextrans; D015609:Organotechnetium Compounds; C034146:technetium Tc 99m dextran; D013667:Technetium