Note that in 2017 the use of some of these linear agents was suspended or restricted in the European Union (EU) due to concerns about potential free gadolinium toxicity. Additionally that year, production and distribution of two agents (Ablavar® and OptiMark®) were voluntarily terminated by their manufacturers and have been removed from previous versions of the table.
The ionic radius of Gd+3 (108 pm) is very close to that of Ca+2 (114 pm). Free gadolinium is therefore a competitive inhibitor of physiologic processes that depend on Ca+2 influx, including voltage-gated calcium channels and the activity of some enzymes. All Gd-based MR contrast agents therefore use some sort of ligand to chelate (contain) the free ion and reduce its high toxicity.
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Bellin M-F, Van Der Molen AJ. Extracellular gadolinium-based contrast media: an overview. Eur J Radiol 2008; 66:160-167.
de Haën C. Conception of the first magnetic resonance imaging contrast agents: a brief history. Top Magn Reson Imag 2001; 12:221-230.
European Medicines Agency. Final opinion restricting use of linear gadolinium agents. 23 Nov 2017.
Rohrer M, Bauer H, Mintorovitch J et al. Comparison of magnetic properties of MRI contrast media solutions a different magnetic field strengths. Invest Radiol 2005; 40:715-724.
Are non-ionic gadolinium contrast agents better than ionic ones?
What are the important physical properties to consider when choosing a contrast agent?