title: In vivo chemistry of 99mTc-chelates.
abstract: The structure-activity relationships involved in the in vivo localization and clearance of 99mTc-chelates is reviewed. Most 99mTc-chelates used for renal studies are mixed function agents and their uptake in the kidney is affected by the presence or absence of stannous ions; only a relatively few chelates are almost exclusively cleared from the body by glomerular filtration or tubular excretion. The uptake of 99mTc-phosphates and -phosphonates in metabolically active and metabolically inactive bone and the plasma clearance rate of these complexes depend upon the structure of the complexing ligand. 99mTc-chelates considered optimal for hepatobiliary imaging have a high liver extraction efficiency, are rapidly transported through the liver and have a comparatively slow renal clearance rate. Even though the elucidation of the in vivo behavior of 99mTc-chelates continues, quantitating structure-activity relationships requires that the structure of the chelates be carefully characterized, both before and after injection.
mesh_terms: D000818:Animals; D001659:Biliary Tract / Q000000981:diagnostic imaging / Q000378:metabolism; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000378:metabolism; D002614:Chelating Agents / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000378:metabolism; D008099:Liver / Q000000981:diagnostic imaging* / Q000378:metabolism; D011877:Radionuclide Imaging; D013329:Structure-Activity Relationship; D013667:Technetium / Q000378:metabolism*
chemical_list: D002614:Chelating Agents; D013667:Technetium