title: Relaxivity of Gd-based contrast agents on X nuclei with long intrinsic relaxation times in aqueous solutions.
abstract: The relaxivity of commercially available gadolinium (Gd)-based contrast agents was studied for X-nuclei resonances with long intrinsic relaxation times ranging from 6 s to several hundred seconds. Omniscan in pure 13C formic acid had a relaxivity of 2.9 mM(-1) s(-1), whereas its relaxivity on glutamate C1 and C5 in aqueous solution was approximately 0.5 mM(-1) s(-1). Both relaxivities allow the preparation of solutions with a predetermined short T1 and suggest that in vitro substantial sensitivity gains in their measurement can be achieved. 6Li has a long intrinsic relaxation time, on the order of several minutes, which was strongly affected by the contrast agents. Relaxivity ranged from approximately 0.1 mM(-1) s(-1) for Omniscan to 0.3 for Magnevist, whereas the relaxivity of Gd-DOTP was at 11 mM(-1) s(-1), which is two orders of magnitude higher. Overall, these experiments suggest that the presence of 0.1- to 10-microM contrast agents should be detectable, provided sufficient sensitivity is available, such as that afforded by hyperpolarization, recently introduced to in vivo imaging.
authors: Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors: Ruud B
authors: RB
authors: van Heeswijk
authors: Sabrina
authors: S
authors: Laus
authors: Florence D
authors: FD
authors: Morgenthaler
authors: Rolf
authors: R
authors: Gruetter
mesh_terms: D002250:Carbon Radioisotopes / Q000494:pharmacology; D002614:Chelating Agents / Q000737:chemistry; D003287:Contrast Media / Q000494:pharmacology*; D005561:Formates / Q000737:chemistry; D005682:Gadolinium / Q000494:pharmacology*; D007091:Image Processing, Computer-Assisted; D008094:Lithium / Q000494:pharmacology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D012680:Sensitivity and Specificity; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D002250:Carbon Radioisotopes; D002614:Chelating Agents; D003287:Contrast Media; D005561:Formates; D009942:Organometallic Compounds; D012996:Solutions; D014867:Water; C030544:formic acid; D008094:Lithium; D005682:Gadolinium