title: Kinetic sensitivity of a receptor-binding radiopharmaceutical: technetium-99m galactosyl-neoglycoalbumin.
abstract: Kinetic sensitivity is the ability of a physiochemical parameter to alter the time-activity curve of a radiotracer. The kinetic sensitivity of liver and blood time-activity data resulting from a single bolus injection of [99mTc]galactosyl-neoglycoalbumin [( Tc]NGA) into healthy pigs was examined. Three parameters, hepatic plasma flow scaled as flow per plasma volume, ligand-receptor affinity, and total receptor concentration, were tested using [Tc]NGA injections of various molar doses and affinities. Simultaneous measurements of plasma volume (iodine-125 human serum albumin dilution), and hepatic plasma flow (indocyanine green extraction) were performed during 12 [Tc]NGA studies. Paired data sets demonstrated differences (P(chi v2) less than 0.01) in liver and blood time-activity curves in response to changes in each of the tested parameters. We conclude that the [Tc]NGA radiopharmacokinetic system is therefore sensitive to hepatic plasma flow, ligand-receptor affinity, and receptor concentration. In vivo demonstration of kinetic sensitivity permits delineation of the physiologic parameters that determine the biodistribution of a radiopharmaceutical. This delineation is a prerequisite to a valid analytic assessment of receptor biochemistry via kinetic modeling.
authors.affiliation: Department of Radiology, University of California, Davis, Medical Center, Sacramento 95817.
authors.forename: D R
authors.initials: DR
authors.lastname: Vera
authors.forename: E S
authors.initials: ES
authors.lastname: Woodle
authors.forename: R C
authors.initials: RC
authors.lastname: Stadalnik
mesh_terms: D000418:Albumins / Q000378:metabolism / Q000493:pharmacokinetics*; D000818:Animals; D007700:Kinetics; D008024:Ligands / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008102:Liver Circulation; D009942:Organometallic Compounds / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D015609:Organotechnetium Compounds; D010953:Plasma Volume; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism*; D012709:Serum Albumin; D013552:Swine; D013667:Technetium / Q000097:blood / Q000378:metabolism*
chemical_list: D000418:Albumins; D008024:Ligands; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; D011956:Receptors, Cell Surface; D012709:Serum Albumin; C036586:technetium Tc 99m neogalactoalbumin; D013667:Technetium