Relaxivity of Gd-based contrast agents on X nuclei with long intrinsic relaxation times in aqueous solution

AUTHORS: van Heeswijk RB, Laus S, Morgenthaler FD, Gruetter R

Magnetic Resonance Imaging, 25(6): 821–825, July 2007

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ABSTRACT

The relaxivity of commercially available gadolinium-based contrast agents was studied for X-nuclei resonances with long intrinsic relaxation times ranging between 6 and 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 ∼0.5 mM^-1 s^-1. Both relaxivities allow the preparation of solutions with a predetermined short T₁ 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 ∼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 two orders of magnitude higher. Overall these experiments suggest that the presence of 0.1-10 μM contrast agents should be detectable, provided sufficient sensitivity is available, such as that afforded by hyperpolarization, recently introduced to in vivo imaging.

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Module: MRI