Magnetic Resonance Im Relaxivity of Gd-based contrast agents on X nuclei with long intrinsic relaxation times in aqueous solutions

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 C formic acid had a relaxivity of 2.9 mM 1 s , whereas its relaxivity on glutamate C1 and C5 in aqueous solution was ~0.5 mM 1 s . 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. Li has a long intrinsic relaxation time, on the order of several minutes, which was strongly affected by the contrast agents. Relaxivity ranged from ~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 , which is two orders of magnitude higher. Overall, these experiments suggest that the presence of 0.1to 10-AM contrast agents should be detectable, provided sufficient sensitivity is available, such as that afforded by hyperpolarization, recently introduced to in vivo imaging. D 2007 Elsevier Inc. All rights reserved.