Magnetic field dependence of longitudinal relaxation rates of solutions of various protein-gadolinium3+ chelate conjugates.
Bovine serum albumin (BSA) and porcine serum fibrinogen (FIB) were multiply labeled with gadolinium3+ by using three different ligands: DTPA dianhydride, isothio-cyanato-benzyl-DTPA (ITCB-DTPA), in which none of the five coordinating carboxylates is employed for macromolecular linkage, and isothiocyanatobenzyl-TRITA, a macrocyclic ligand. The nuclear magnetic resonance dispersion (NMRD) profiles of the protein-(Gd chelate) conjugates were characteristic to each chelate involved, possessing, as expected, greater longitudinal relaxivities than the corresponding Gd chelates alone and exhibiting prominent peaks at the proton Larmor frequency range of 10 to 40 MHz. Particularly favorable relaxation enhancement was measured in the solutions of BSA-(ITCB-DTPA-Gd) at this field range. When the number of chelates conjugated with protein increased, up to 163 Gd chelates per one fibrinogen, a progressive decrease in relaxivity was observed. This study demonstrates the relaxation properties of novel macromolecular contrast agents designed for magnetic resonance imaging.
Department of Diagnostic Radiology, University of Turku, Finland.
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Niemi
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Reisto
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Hemmilä
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Kormano
D000818:Animals; D002417:Cattle; D005340:Fibrinogen; D005682:Gadolinium; D019786:Gadolinium DTPA; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011506:Proteins; D012710:Serum Albumin, Bovine; D013552:Swine
D009942:Organometallic Compounds; D011506:Proteins; D012710:Serum Albumin, Bovine; D004369:Pentetic Acid; D005340:Fibrinogen; D005682:Gadolinium; D019786:Gadolinium DTPA